gerd r. weber (1992) global warming - the rest of the story

First it was acid rain, then the ozone hole. Now, CO2 in the air is supposed to bring on a climate catastrophe. Is global warming really a threat, are the polar ice caps in danger of melting and are coastal areas of habitation under threat of a deluge? Do we therefore need an energy-CO2 tax?

The author explains in straight-forward language what climatological research indicates about the following questions:

• What is and how does the greenhouse effect work? What does that mean for life on earth?

• Why is a rise in temperature feared?

• How and for what reasons has climate changed over the centuries and what role was played by the greenhouse effect?

• What do we really know about the effect of a growing concentration of greenhouse gases in the atmosphere and what do current computer programs make of that ?

• How do plants and algae cope with increased CO2 and temperature through photosynthesis?

Table of Contents

Introduction: Global warming Fact and Fiction .......................................7

1. The Greenhouse Effect: Welcome to Life on Earth..............................................9

2. A Look Ahead - Is The Future Ours to See? ...........................................31

3. On The Threshold To Climate Modeling:

The Carbon Cycle.........................................................46

4. The Acid Test: Models vs. Reality. ..............................76

5. The Longer View: Factors Other than Trace-Gases

that Affect Climate .................................................... 110

6. A Changing Perspective .............................................129

7. The Unreal Solutions - Grappling with CO2...................................................139

8. The Real Solutions the Premier Candidate ...............................................150

INTRODUCTION

Facts and fiction about global warming

First it was acid rain, then the ozone hole and now the latest in environmental disasters headed our way is the greenhouse effect - or global warming as it is sometimes called. Rising tides, scorching heat, melting ice caps: Hardly a day passes by when the media does not administer us our daily dose of doom.

Yet, even though the greenhouse effect has been the subject of intense scientific debate for quite some years, it did not capture much public and media attention until the summer of 1988, when the worst drought in decades hit the US. That prompted some scientists to claim that this was the final proof that the greenhouse effect had in fact arrived.

The drought could indeed not have come at a better time, since congressional hearings on the greenhouse problem, and possible legislation to counter it, had been previously moved out of the winter session into the summer - to get better media attention in the midst of a heat wave.

The gamble worked out well indeed. In fact, some of the people involved concede that nature did more for them in 15 weeks than they were able to achieve in 15 years.

Since then, the media barrage has continued unabated. By and large, the public is convinced that some terrible things are coming our way with the greenhouse effect; and the international greenhouse conference carousel is turning ever faster, each one trying to outdo the preceding one on suggestions for what to do, how to contain global warming, and painting an ever gloomier picture of the coming climatic change - global change.

Although the general public hardly noticed the fact, the scientific community is still deeply divided on most issues surrounding the greenhouse problem.

Since the public policy issues which may emerge from a global climate change - or from possible measures to avert such a change - are of immense proportions, it seems appropriate for us to critically examine the envisioned climatic changes, their possible impact on human activities, and especially the scientific basis from which they were derived.

A number of scientists have expressed concern over possible

8 GLOBAL WARMING

future climate changes. In a problem of this potential magnitude, one which affects almost every facet of our lives, concern is justified - but this concern alone is not enough to come to grips with the issue. What is necessary is a sound scientific assessment of the greenhouse effect, changes in the climate, and their possible impact on our lives which are supposed to result, and a closer look at some of the proposed countermeasures.

This book will provide the reader with the current state of knowledge on all the issues related to the greenhouse effect and the possible future direction of climate, and with an action plan to cope with a possible climate change.

We will take a journey through the wonderland of science. We will first look at the greenhouse effect and examine its meaning and importance for life on earth; second, we will discuss why it is increasing, and how this may be affecting the climate. Then we will look at the climate itself, what it is, what might cause it to change in general, how it has evolved through the centuries, and we will determine whether we can already see some signs of the greenhouse effect. We will also try to assess how life on earth will change if the climate does change the way some people expect it. And we will of course probe into the question of whether climate will really change the way some people expect.

Finally, we will take stock of the situation and try to determine where we are really headed with our climate by examining which options we have to fight a global warming, if that is what we decide to do.

The book is kept simple. Everyone interested in the problem can digest it easily without fearing that he or she will be overwhelmed by a mass of incomprehensible science or intricate math.

Anyone interested in digging deeper into the subject will find an extensive list of references which is designed to back up every factual statement made in the text.

You will come across a number of interesting items you probably never heard about from the media before, things stranger than fiction, at times controversial, but always elucidating: In other words, the rest of the story.

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1.

The Greenhouse Effect: Welcome To Life On Earth

When we hear about the greenhouse effect, our first reaction is: rising tides, scorching heat, melting ice caps, impending disaster. That is how we see it in the newspapers or on TV. But surprisingly enough, it is the greenhouse effect which turned this planet from an uninhabitable piece of ice into the (sometimes) hospitable planet we know today. Since you have often heard the greenhouse effect equated with disaster, you might ask: why is that?

Well, we have to differentiate between the naturally occurring greenhouse effect which helped create the climatic conditions on earth as we know them today, and the additional, man-made greenhouse effect thought to result from man's various activities.

Before we analyze this additional greenhouse effect, which is the one we are interested in because it is supposed to lead to all those dire consequences, let us first take a look at the natural greenhouse effect and what determines the temperature and climate on earth as we know it today. That may put us in a better position to understand how the greenhouse effect - natural and man-made - really works.

Could Earth Have A Climate Like Venus?

Planetary science has determined a number of factors which have a bearing on the exact history, evolution, and current state of a planet's climate, from which we identify three major ones:

(1) The planet's astronomical properties, such as its distance from the sun.

(2) The physical properties of the planet (i. e. its size, rate of rotation).

(3) Its chemical properties, especially those of the atmosphere. Everyone will agree that distance from the sun could easily be

the most important factor determining the climate of a planet: the closer it is to the sun, the more solar radiation it will receive and the warmer it will get.

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The next two important factors are size and chemical composition of the planet, and of its atmosphere in particular. Those two factors are interrelated in a strange way in their importance to climate: The planet's gravitational pull, i. e. its mass- attraction depends on its size (or more precisely, mass). If a planet is so small that its gravitational pull cannot hold an atmosphere, there would not be any climate, because without an atmosphere there is no climate.

In fact, the ability of a planet to hold an atmosphere also depends on its proximity to the sun, because even if a planet some distance away from the sun is able to hold an atmosphere, it may lose that ability closer to the sun since the increasing heat may then cause the atmosphere to "evaporate" into space. On the other hand, if that planet moved further away from the sun, its atmosphere might eventually freeze or condense onto the planet's surface. All of this illustrates the importance of various astronomical factors on the climate of a planet.

Mercury is an example of a planet too small and too hot (because of its proximity to the sun) to hold an atmosphere. Venus, about the size of the earth, but much closer to the sun, is much hotter than the earth, partially because of its proximity to the sun and partially because of the different chemical composition of its atmosphere.

Let us now assume that we have a planet Earth at its position in the solar system with its given astronomical, physical and chemical properties. Science then gives us the tools to compute its temperature simply from the solar energy-flux reaching it. The result is that the average temperature of the planet would be a brisk 0° F, certainly not enough to allow any life on earth the way we know it.

Now, the observed temperature on earth is about 60° F. That difference of 60°F is due to the fact that our planet has an atmosphere, and that this atmosphere has its current chemical composition. This ability of our atmosphere to warm up the climate is due to the greenhouse effect.

The analogy to a greenhouse is drawn because, comparable to the glass in a greenhouse, the atmosphere lets through the sun's radiation, which warms up the earth's surface, and its atmosphere inhibits the escape of this heat into space. This analogy is actually not quite correct, and some scientists have qualms against using it. But for our present discussion, it will serve in view of the fact that it has gained such wide public recognition.

The actual magnitude of the greenhouse effect, i.e., the amount


of warming, is due to the chemical composition of the earth's atmosphere. If we take a closer look at the atmospheric constituents which play a role in this, we come across water vapor as the most important greenhouse gas. It alone accounts for fully 40°-50° of the total 60° F greenhouse warming. The rest is made up of some other trace-gases which occur in the atmosphere, CO2 being at the top of that list.

The All Important Trace-Gases

You may ask right away, how does it happen that only the trace constituents contribute to the greenhouse effect? What about the other the major constituents of the earth's atmosphere, namely nitrogen and oxygen: do they play a bigger role? (Table 1, Atmo- spheric constituents)

To explain this, we have to take a quick look at the molecular structure of the various gases in our atmosphere and their relationship to the inner mechanism of the greenhouse effect.

Every object gives off thermal radiation. The spectrum of that radiation, i.e., the radiative energy given off at a particular wavelength, is intimately related to the temperature of that object. The wavelength at which the peak of this radiation occurs varies in- versely with temperature: the hotter the object, the shorter the wavelength. The radiation we receive from the sun is at relatively short wavelengths, because the surface of the sun is very hot compared to the earth's temperature and therefore the radiation emanating from earth is at relatively long wavelengths.

Now, the radiation we receive from the sun at the earth's surface and the radiation an observer from space observes emanating from the earth and its atmosphere is modified by the atmosphere: the molecules of the various gases which make up the earth's atmosphere are in perpetual motion; they vibrate and rotate in a way which is inextricably linked to their molecular structure. They take the energy necessary for that motion out of the background thermal radiation field. The key point now is that each molecule, owing to its properties, can only use the radiative energy of one or several small, well defined spectral regions for that motion. Molecules of a greenhouse gas will not use - absorb - (to any significant extent) thermal radiation from the solar spectrum which is at shorter wavelengths, but instead the radiation from the longer wavelengths which are more characteristic of earth's temperature. By absorbing and re-radiating the thermal

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Table 1: Composition of Earth's atmosphere

Gas Percentage Mixing Ratio in ppm

Nitrogen (N2) 78.084 Oxygen (O2) 20.946 Argon (A) 0.934 Neon (Ne) 0.00182 18.2 Helium (He) 0.000524 5.24 Nethane (CH4) 0.00015 1.5 Rrypton (Rr) 0.000114 1.14 Hydrogen (H2) 0.00005 0.5

Variable constituents

Water vapor (H2O) 0-3

Carbon dioxide (CO2) 0.0353 353 Carbon monoxide (CO) <100 Sulphur dioxide (5O2) 0-1 Nitrogen dioxide (NO2) 0-0.2 Ozone (O3) 0-2

Source: After L. J. Battan, Weather, 1974.

energy from earth, the greenhouse gases prevent the energy from escaping into space - thereby giving rise to the greenhouse effect.

Nitrogen and oxygen molecules, which make up the bulk of our atmosphere, do not have any significant spectral regions in the long wavelenths to absorb the earth's - or terrestrial - radiation, and therefore, they are not major greenhouse gases. The terrestrial spectrum and the regions where various trace-gases are active is shown in Fig. 1. There we can identify the extent to which our atmosphere is transparent and the extent to which it is opaque to radiation emanating from our planet. This figure then shows the regions within the terrestrial spectrum where the natural greenhouse effect, which created our current, hospitable conditions on earth, occurs.

Before we get into the additional, man-made greenhouse effect, there is one more point to mention, one which has some importance when analyzing the individual contribution of any trace-gas to the greenhouse effect, man-made or natural. Owing to the molecular structure of the greenhouse gases, there may be regions in the spectrum where the molecules of different trace-gases are


active at the same time, causing some overlap which makes it hard to define the greenhouse contribution of each individual com- ponent.

This is particularly the case with water vapor. The concentration of water vapor, by far the most important and most abundant greenhouse gas, varies widely from place to place, season to season, and even with altitude in the atmosphere. This is in stark contrast to most other greenhouse gases, which are fairly well mixed in the atmosphere and show very little spatial and short- term variation over time.

Therefore, the degree of overlap between various greenhouse gases and the magnitude of the natural greenhouse effect itself should vary strongly with the concentration of water vapor. The argument would therefore be that the natural greenhouse effect is most pronounced where we find the most water vapor in the atmosphere, and least pronounced where we find the least amount.

This is exactly the case. In order to identify those regions on earth where the water vapor concentrations are highest, let us also consider that the amount of water vapor the atmosphere can hold without condensing increases strongly with temperature (see Fig 2). As a rule of thumb, for each 20° F temperature rise, the amount of water vapor the atmosphere can hold without condensing roughly doubles.

Figure 1. Wavelengths of thermal radiation and absorption regions of various trace gases.

Source: After Ramanathan et al., 1987; U.S. Dept. of Energy Report DOE/FE -164

14 GLOBAL WARMING

Obviously then, the natural greenhouse effect should be strong in the tropics and in those regions where we find a combination of high temperatures and high water vapor content. Globally, those areas are the tropical oceans, and in particular, the western tropical Pacific.

In the US, those regions are the southern seaboard, including the Southeast and Florida.

In the desert Southwest on the other hand, we do find high temperatures, but only very little water vapor and we therefore do not expect the natural greenhouse effect to be very pronounced there.

Furthermore, since temperatures decrease rapidly with altitude in the atmosphere, the water vapor content, and with it the water vapor related warming at the earth's surface, also decreases rapidly. In fact, most of the water-vapor related warming at the earth's surface originates in the atmosphere's lowest mile.

The natural greenhouse effect is also relatively small in the cold regions of the earth, such as the Arctic, where the air can hold only very little water vapor (see Fig. 2). By the same token, the natural greenhouse effect due to water vapor is less in winter than in summer at any given location. Therefore, increasing the amount of water vapor in the air increases the natural greenhouse effect.

There are limits to that, however. We know that the air is already so rich in water vapor in the lower atmosphere of the tropics that the absorbtive regions in the spectrum are nearly saturated. Neither an increase in water vapor nor an increase of those trace- gases which overlap with water vapor will further enhance the greenhouse effect, at least not to a significant degree. There will therefore be no additional warming at the earth's surface.

We may already conclude that any effect we expect to see as a result of increasing trace-gases should be smallest in the lower atmosphere of the tropics.

However, this short synopsis only considers the radiative effects of various trace-gases, and does not consider the possible feedback mechanisms which may alter the simple conclusions drawn here. More detail will be given on these later on in the section on climate modeling.

To further illustrate the way the natural greenhouse effect works, let us consider the following:

In diurnal temperature variations, the sun's radiation is of course the major factor determining temperature. On a cloudy day in summer, it is generally much cooler than on a sunny day, everything else being equal. If we now assume equal amounts of


sunshine at two different locations, one being very dry, the other being moist, we would notice a difference in the diurnal temperature variation. The dry location warms up about as much as the moist one during the day, but during the night, the dry location cools off much more than the moist one. The difference is due to the greenhouse effect of water vapor, which, during the night, acts as a "blanket" which is missing in the dry location. Therefore, typical day-to-night variations in temperature over Florida, for example, are considerably less than over Arizona. The "blanket" of the natural greenhouse effect prevents our planet from cooling off too much and gives us our present climate.

Holes In The Greenhouse Blanket

But this blanket has a few holes in it, through which some thermal radiation escapes from the earth - cooling it off in the process and keeping its temperature at its present level. We can identify those "holes" by the "gaps" in Fig. 1.

Enter the man-made greenhouse effect. Due to man's activities (the famous line you may have heard before), certain trace-gases are emitted into and build up in our atmosphere, which, as luck would have it, and owing to their molecular properties, absorb thermal radiation right in those areas of the blanket where the holes are located. In other words, the trace-gases "plug those holes" in the blanket and prevent radiation emanating from the earth's surface and its atmosphere from escaping into space, thereby causing it to remain with us instead. This leads to a warming of the earth and its atmosphere. This, in a nutshell, is the greenhouse theory.

The details, however, will become complicated. They depend on the way the climatic system - the intertwined action of atmosphere, oceans, and icesphere - responds to an increase of downward thermal radiation due to an enhanced greenhouse effect. We will deal with the response of the climatic system to the increase of the greenhouse effect at a later stage; suffice it to say at this point that the increase in downward thermal radiation is subject to considerable uncertainty itself, but it is still the best known variable in the entire ball game.

The uncertainties arise mainly as a result of the overlap mentioned above, which must obviously vary as a function of water vapor concentration, and therefore as a function of geography, season, and altitude in the atmosphere. But overlapping regions

16 GLOBAL WARMING

between various radiatively active trace-gases themselves are also important, and insufficient knowledge of their precise absorption characteristics can easily result in large errors in the calculated greenhouse radiation.

So, while we can generally conclude that an increase in trace-gas concentrations will lead to an increase in thermal radiation at the earth's surface and in the atmosphere, it is very hard to estimate the magnitude of that increase, and it is even more difficult to estimate what exactly will happen to climate as a result of that increase in thermal radiation, other than that it will probably lead to a warming of the earth's atmospheric system - the magnitude of that warming being again subject to considerable uncertainty.

We will now temporarily stop looking at climate, and turn our attention to those trace-gases and human activities which are thought to be responsible for the enhanced greenhouse effect. We do this now in order to determine how much of an additional greenhouse forcing we can expect in coming decades and why we should expect it. We will then return to the climate, using this information to assess the kind of climatic changes we might expect to result from the additional greenhouse effect.

Players In The Greenhouse Act

Let us now look at those gases and human activities which contribute to "plugging the holes" in our atmospheric blanket. We will do this in several steps:

1. Identify the gases and human activities which contribute to their emission.

2. Examine their past emission trends. 3. Examine their expected future emission trends. 4. Examine their individual contribution to the greenhouse ef-

fect - past, present, future

Table 2 identifies those trace-gases considered "radiatively active", i.e. those which contribute to plugging the holes in the atmospheric blanket. Table 2 gives the estimated contribution of each of those gases to the greenhouse effect at present emission rates. Table 2 also introduces a concept called "Global Warming Potential" (GWP), which gives the additional greenhouse effect of a greenhouse gas over a specific time horizon relative to CO2. The relative contribution of a particular greenhouse gas varies with

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Table 2: Summary of Key Greenhouse Gases

CO2 CH4 N2O CFC-11 CFC-12

Pre-industrial atmospheric concentration (1750 -1800)

280 ppm 0.8 ppm 288 ppb 0 0

Present atmospheric concentration (1990)

353 ppm 1.72 ppm 310 ppb 280ppt 484ppt

Present rate of annual increase

1.8 ppm (0.5 %)

0.015 ppm (0.9 %)

0.8 ppb (0.25 %)

9.5 ppt (4%)

17 ppt (4%)

Specific Greenhouse Potential (per unit mass)

1 58 206 3970 5750

Global Warming Potential (100 Years) (per unit mass)

1 21 290 3500 7300

Source: After IPCC, 1990.

time because of differences in its atmospheric lifetime. If it is short, its importance vis-a-vis the other trace-gases will decrease; if it is long, it will remain important. It should be pointed out, however, that a number of assumptions are made in this concept which may not necessarily hold up to future scientific scrutiny. This is notably the case with the assumed lifetime of CO2, 120 years. In the following we will therefore exclude the GWP from our deliberations because of its speculative and highly uncertain character. Generally, we can divide those gases into two subgroups:

1. Gases which are a natural part of our atmosphere, but which increase due to various activities to be identified, and

2. Gases, which do not naturally occur in our atmosphere and which are exclusively a product or by-product of man's various industrial activities.

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1. Naturally occurring trace-gases Carbon Dioxide (CO2)

The first trace-gas we wish to direct our attention to is carbon dioxide, a natural constituent of our atmosphere and by far the most abundant of the trace-gases we are now considering. Table 2 gives the atmospheric concentrations by volume, i.e., number of molecules of the trace-gas per number of molecules of air. 1 ppm means that there is one part of the particular trace-gas per 1 million parts of air. Obviously, we are talking about small concentrations indeed. The current atmospheric concentration of CO2 is about 350 ppm. It has increased since 1958, the first year modern and accurate measurements were taken, by about 35 ppm. The total increase since man began injecting CO2 into the atmosphere through his various activities - mostly clearing forests and burning fossil fuels (i.e., wood, coal, oil, and gas) - has been estimated to be around 70 ppm. Since CO2 contributes the largest part to the man-made greenhouse effect, (see Tab. 4, present contribution to the greenhouse effect) the current debate over the greenhouse effect centers on, but is not restricted to, strategies to reduce CO2

emissions, i.e., reduce the burning of fossil fuels and biomass. We will now analyze past and present patterns of CO2 release in

terms of type of fuel and geographical region. Table 3 shows the present best estimate of the contributions of

each of the fossil fuel types, including biomass burning, to current emissions. The total release of CO2 due to fossil fuel use can be fairly well documented since the middle of last century, and this is shown in fig. 3. The contribution thought to have been made by biomass burning is considerably more uncertain and the line in fig. 3 indicating biomass burning should be considered tentative - but it still represents best current estimates. The share of biomass burning in total emissions since the middle of last century may then have been in the neighborhood of 40 percent, a sizable amount indeed. In past decades, the amount released by biomass burning and changes in land use may even have been approximately 50 percent of the amount released by fossil fuel burning.

The generally rapid increase of fossil fuel related emissions has experienced several small dents during the two major wars of this century, and again during the great depression of the 1930s, and once more following the energy crises of the 1970s. In recent years, fossil fuel use and CO2 emissions have risen again and are presently (1991) at an all time high of about 6 billion tons of carbon per year.

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Table 3: Global CO2-emissions by fossil energy use including the estimated biospheric emissions in the late 1980s

Billion Relative carbon Tons of content per carbon in % unit of energy

Coal 2.4 32 1.0

Oil 2.4 32 0.8

Gas 0.9 12 0.6

Cement production 0.2 3 -

Biosphere (De-forestation/Land use

changes) 1.6 21 -

Sum 7.5 100

Source: After IEA, 1991.

Fossil fuel use is generally expressed in tons of carbon. This number is always lower than, say, tons of coal or tons of oil, because the amount of carbon contained in those fuels is always less than the actual weight. The difference is due to non-carbon compounds in those fuels.

The annual rate of increase in carbon emissions has been roughly 4 percent per year following WW II, and a little less than 2 percent between 1973 and 1980. Following the second oil crisis in 1979-1981, there was actually a decrease in the early 1980s. Early use of fossil fuels around the turn of this century was mostly restricted to coal, which was at first slowly, then rapidly replaced by oil after WW II. The use of gas has risen steadily, especially in recent years. Following the first oil crisis in 1973 and notably after the second one in 1979, the role of oil gradually decreased, while coal steadily regained ground lost in earlier decades. Only after the oil price collapse of 1986 did oil increase its share again.

If we now look at the contribution of individual countries to global CO2 emissions (Fig. 4), the US emerges as the largest source at a share of 24 percent, followed by the USSR with 19 percent, Western Europe (Europea Community, EC 12) with 14 percent, China 9 percent, and Japan 5 percent, for a total of about 70 per-

20 GLOBAL WARMING

Figure 2. Temperature and saturation mixing ratio. Source: After Anthes et al., 1978

Figure 3. CO2-emissions from fossil fuel use and from land use changes between 1860 and 1980. Source World Resources Institute, 1991.


Figure 4. Trends of C02 emissions from fossil fuel use by major geographic region (1 Gt = 1 billion metric tons). Source: US: Department of Energy, Report DOE/FE-0164.

cent, or more than two thirds of total worldwide emissions. There- fore, the industrialized countries contribute the lion's share of global CO2 emissions due to fossil fuel use. The lesser developed countries (LDCs), on the other hand, contribute most of the emissions due to biomass burning, currently estimated at 2 to 4 Gt per year.

The relative share of the industrialized countries of total fossil fuel use (and CO2 emissions) has been continuously losing ground to the newly industrializing (NICs) and lesser developed countries. For example, between 1973 and 1988 the share of the NICs and LDCs of total oil consumption increased from 15 to 28 percent.

There are several obvious reasons for this. First of all, fossil fuel consumption in the highly industrialized countries of the West has reached partial saturation, whereas in most of the NICs and particularly in the LDCs, fossil fuel use is still in its nascent stages.

Example: If everybody drives an automobile - which burns fossil fuel and emits CO2 - there cannot be an increase from additional automobiles anymore, because one person cannot drive two cars at the same time. A similar argument can be made for, say, air-conditioners and other household appliances operated with electricity generated by a fossil-fuel fired power plant.

In short, in the industrialized countries, saturation of energy use

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Table 4: Sectoral contributions to the greenhouse effect. Estimated percentages for global emissions in the late 1980s.

in% CO2: Power generation

Transport Industry Residential / commercial Remaining fossil energy use De-forestation/land use changes

13 13 9 7 1

12

Sum CO2 55

Methane (CH4) Nitrous oxide (N2O) CFCs

15 6

24

Total 100

Source: After Warrick et al., 1990; JEA, 1991.

has been reached in many areas, which considerably limits the potential of further increases in energy use and CO2 emissions.

This is certainly not the case in the NICs and LDCs, where per capita use of (fossil) energy is only a small fraction of its counter- part in the industrialized countries. But it is catching up rapidly. Not only that, in contrast to the industrialized countries, where population is fairly stable, population in the LDCs is growing at a staggering rate. Those two factors combined, rapid population growth and growth in energy use in the LDCs and newly industrialized countries, compared to relatively stable population and saturation in energy use in the ICs, explain most of the relative decline of the industrialized countries' share of fossil fuel use and CO2 emissions in recent decades.

This trend is expected to continue in the future; and indeed, since most of the concern about trace-gas emissions and climatic changes is concern about future emission increases, energy use and CO2 emission patterns in fast growing areas of the world will assume a key role in coming decades. Furthermore, since energy use is largely, but not completely, tied to economic activity, the CO2

emission pattern will behave in a way very similar to the changing pattern of economic activity, which changed dramatically after


WW II. The once dominant economic powerhouse USA saw its relative share of world gross domestic product (GDP) slowly erode, first at the expense of other industrialized countries which were rebuilding their war torn economies, and now increasingly to the NICs and LDCs, a trend which is likely to continue in the future.

The widespread stagnation of energy use in the industrialized countries after the two oil shocks of the 70s can furthermore be interpreted as a frantic attempt to lessen the dependence on foreign oil. In the '70s, energy conservation measures were insti- tuted in almost every industrialized country, and did indeed bear some fruit. However, the turmoil initially suffered within the industrialized countries as their economies shifted to a more energy efficient (and less oil dependant) mode was considerable: The two severe recessions experienced in 1974 and 1980-1982 were largely due to the drastic oil price hikes. Once oil consumption declined, however, and especially after market share drifted away from the OPEC countries, the full benefits of energy use reduction became apparent. There are some inherent dangers in this very rosy picture which we are going to discuss in more detail in the section dealing with future trends: First, due to increased consumption, prices may rise again drastically, possibly leading to another supply shock, which may again bring us the deleterious economic consequences we witnessed in the 70s; and secondly, the restorat- ion of OPEC's power subsequent to Operation Desert Storm.

In addition to increasing energy efficiency and saturation in energy use, there is one more fundamental factor responsible for the slow rise in energy use in the industrialized countries over the last 15 years: the structural shifts within our economies. The US has been in the middle of a transformation from a manufacturing economy, which is energy intensive, to a service economy, which is decidedly less energy intensive. This industrial policy is expected to continue in coming decades.

Example: If one creates a certain amount of GDP by producing steel, a lot more energy is used than by creating the same GDP through financial services or the production of computers.

Let us now look at the various activities of mankind which contribute to the emission of CO2 on a global scale. It should be noted that large differences might exist from country to country and from region to region (see table 4). For example, in the US, automobile driving contributes 29 percent to CO2 emissions, compared to 13 percent globally. Obviously, there is no "prime", or overriding worldwide activity which is the CO2 and greenhouse

24 GLOBAL WARING

source, a conclusion which becomes even more apparent when we consider the greenhouse contribution of trace-gases other than CO2. In fact, in this list of greenhouse activities, the largest single contribution is made by the CFCs, which we will deal with later on (see Tab. 4).

Methane The next gas in our category of natural constituents is methane,

CH4, with an estimated greenhouse contribution of 15 percent. Methane is emitted largely by natural sources such as swamps, marshes, rice fields, termites and ruminants (see table 5). Its atmospheric concentration is much lower than that of CO2, but it is growing at a much faster pace -1.0 percent per year - and in addition is a much more powerful greenhouse gas. One kg of methane has the greenhouse power of about 58 kg of CO2 (see Tab. 2).

Science is somewhat at a loss to explain methane's rapid rise

Table 5: Estimated sources and sinks of methane.

Annual Release (Tg CH4) Range (Tg CH4)

Source Natural Wetlands (bogs, swamps tundra, etc) 115 100-200 Rice Paddies 110 25-170 Enteric Fermentation (animals) 80 65-100 Gas Drilling, Venting, Transmission 45 25-50 Biomass Burning 40 20-80 Termites 40 10-100 Landfills 40 20-70 Coal Mining 35 19-50 Oceans 10 5-20 Freshwaters 5 1-25 H4 Hydrate Destabilization S 0-100

Sink

Removal by soils 30 15-45 Reaction with OH in the atmosphere 500 400-600 Atmospheric Increase 44 40-48

Source: IPCC, 1990.


Table 6: Estimated sources and sinks of N2O.

Range (TgN per year)

Source

Oceans 1.4-2.6 Soils (tropical forests) 2.2 - 3.7

(temperate forests) 0.7- 1 Combustion 0.1-0.3 Biomass burning 0.02 - 0.2 Fertilizer (including ground-water) 0.01-2.2

TOTAL: 4.4 -105

Sink

Removal by soils ? Photolysis in the Stratosphere 7-13

Atmospheric Increase 3- 4

Source: IPCC, 1990.

since the beginning of the industrial revolution, because no industrial activity other than the relatively small sources of coal mining and the exploration and production of oil and natural gas can be related to its growth. It is therefore generally concluded that activities related to food production, notably rice farming and cattle raising, explain most of the rise. The close correspondence between population and methane growth is often cited as supporting evidence for the notion that the CH4 increase is associated with food production - which should continue to increase along with population growth.

N2O - Nitrous Oxide The increased concentration of N2O is thought to contribute

another 6 percent - at current emission rates - to the enhanced greenhouse effect. The reason for its rise in concentration, about 0.25 percent per year, is even more uncertain than in the case of methane. It is generally thought that some contribution is made by the application of nitrate fertilizer, fossil fuel combustion and biomass burning (Table 6).

Ozone The changing concentration of atmospheric ozone is further-

26 GLOBAL WARMING

more thought to make a contribution if not to the greenhouse effect, then to global warming in the following two ways. Ozone is thought to decrease in the stratosphere, the atmosphere's upper level (roughly between 10 and 20 miles above sea level) due to the action of CFCs, which we will briefly discuss in the following paragraph. It is thought to increase in the atmosphere's lower level, the troposphere, as a result of a general increase in nitrogen oxide and hydrocarbon emissons, from which ozone may form in a chain of complex chemical reactions. The decrease of stratospheric ozone would let increased amounts of ultraviolet radiation pass through to the earth's surface, leading to a small, additional warming; whereas an increase of tropospheric ozone would enhance the greenhouse effect, leading to further warming, the total of which is comparatively small.

It may be noted that even though the increase in tropospheric ozone may be thought to counteract the stratospheric decrease, this would only be true to a small extent since the decrease in the stratosphere is expected to be much larger than the tropospheric increase. Because of uncertainties regarding the global ozone increase, no numerical value can presently be attached to the additional greenhouse effect of ozone.

2. Industrial trace-gases CFCs

We now direct our attention to the last group of substances which may alter the earth's radiative balance, and which are indeed heavyweights in their total contribution to the greenhouse effect (see table 4): The chloro-fluoro-carbons, CFCs in short, which do not naturally occur in the atmosphere, and are emitted entirely as a result of man's industrial activities. CFCs are widely used as aerosol can propellants, as refrigerants in mobile and stat- ionary air-conditioning systems, but also as solvents and cleans- ing agents. They were invented in the late 1920s and rapidly put into use after WW II at double-digit growth rates until the mid 1970s, when their use was put under scrutiny for the first time because of their suspected role in stratospheric ozone depletion. The US, adopting a cautious stance, banned their use in some areas already in the 1970s, the most important being aerosol can propellants.

After the discovery of the ozone hole phenomenon, in which they were implicated as playing a significant role, an international


push to sharply reduce their use, or to ban them altogether, gained considerable momentum and resulted in the so-called "Montreal protocol" of 1987, which mandated a 30 percent reduction of CFC use by the year 2000.

Not satisfied with that, further reductions were deemed necessary as the ozone hole over Antarctica seemed to grow ever larger. Those increasing concerns resulted in the "Helsinki Declara- tion" in 1989, in which the signatory countries committed themselves to a complete ban of CFCs by the year 2000.

Not The Greenhouse Effect, But The Ozone Hole... While stratospheric ozone depletion is a matter almost totally unrelated to the greenhouse effect, except for some small interactions we will shortly discuss, it is frequently dealt with con- currently in public debate. Although we will not attempt to give a full account of the complex scientific issues which surround the problem of stratospheric ozone depletion and the ozone hole, a brief digression into the major aspects appears to be useful at this point.

The CFCs, due to their chemical properties, are chemically very stable in the earth's lower atmosphere, and no major mechanisms are known which could break them up. Over longer time spans, however, they are supposed to rise from the troposphere into the stratosphere, breaking through a strong barrier between the two atmospheric levels, called the tropopause, which normally - to a large extent - suppresses atmospheric exchange between the two. Once in the stratosphere, the CFCs would be subjected to the shorter wavelength ultraviolet rays from the sun, which are kept away horn lower atmospheric layers by the ozone layer within the stratosphere.

Those ultraviolet rays now break up the CFC molecules to release chlorine atoms, which in turn act to break up the ozone molecules, without themselves being consumed to any significant extent in the process. Therefore, even relatively minor amounts of CFCs may lead to some ozone depletion. It has been estimated that if present trends continue, - whatever that means - the ongoing release of CFCs may, over time spans of 50 to 100 years, result in a reduction of total atmospheric ozone content by roughly 10 to 15 percent. It should be pointed out that these estimates are widely divergent, and have a history of changing erratically even over short time periods of a few years, due to improvements (or

28 GLOBAL WARMING

apparent improvements) in the modeling schemes of the complex atmospheric chemistry.

Be that as it may, once reports of the ozone hole came out, the scientific community was largely confounded, because none of their hitherto proposed mechanisms could explain the observed rapid and temporary ozone depletion over Antarctica, which occurred in the antarctic spring.

However, scientists smartened up quickly and proposed a scheme which could explain the rapid and temporary ozone depletion. It involves a combination of natural factors met only over Antarctica with anthropogenic CFC release. The bottom line is that the "ozone hole" is a phenomenon which can only occur over Antarctica within the extremely cold stratosphere, which does not otherwise occur anywhere else, and requires a spatial coherence of those cold temperatures during the antarctic winter, combined with the presence of some frozen particles, called polar stratospheric clouds (PSCs). Those PSCs then act as reaction partners with the CFCs at the onset of antarctic spring, and cause the rapid ozone depletion which results in the occurrence of the "hole", i.e., a region of drastically reduced ozone concentrations in the stratosphere. This "hole" disappears a few weeks later when the sun climbs higher over Antarctica and promotes the normal process of photochemical ozone production which takes place in the stratosphere.

Therefore, to stress that point again, the "ozone hole" is a temporary phenomenon, which, due to natural factors, is confined to Antarctica and may well re-appear or disappear in smaller or larger extent depending on what the natural factors - mainly temperatures and PSCs - in the antarctic stratosphere are like.

Furthermore, there is some evidence to suggest that the "ozone hole" might not be an entirely new phenomenon at all, exclusively caused by CFCs, since observations from the 1950s also indicated occurrences of sudden, unexpected and substantial ozone losses over the Antarctic in the spring.

The Ozone Depletion-Greenhouse Link

Temperature is the key word when we now consider links between ozone depletion and the greenhouse effect.

According to the greenhouse theory, we should expect temperatures to rise as a result of a trace-gas increase in the tropo-


sphere, the atmosphere's lower level. But the theory also postula- tes that temperatures in the stratosphere should then go down. However, that would favor the formation of the PSCs, which form only when temperatures are below a certain threshold value. Con- sequently, if temperatures decline in the antarctic stratosphere as a result of the greenhouse effect, we should expect more frequent occurrences of ozone holes in the future if the CFC release continues.

Unfortunately, that is only one half of the story. To make matters even more complicated, scientists have also found out that lower temperatures in the stratosphere - as a result of the greenhouse- effect - will slow down and ameliorate the process of long-term ozone depletion (the one taking place on a 50 to 100 year time scale). Therefore, the greenhouse effect may have a "healing" effect on the long-term ozone depletion and may in fact be beneficial in that sense - but detrimentral with respect to the short-term "ozone holes".

There have been reports recently of "mini ozone holes" over the Arctic. However, these are much smaller features of a decidedly more transient nature and should not in any way be compared to the massive and large-scale ozone destruction which has taken place over Antarctica, other than that the underlying chemistry is essentially the same. But there is no reason to think that those small holes will grow larger, and one day even assume antarctic proportions. The differences between arctic and antarctic atmospheric circulation patterns are too substantial for that.

The implications of a longer term decline of a stratospheric ozone decrease may involve an increase in ultraviolet radiation at the earth's surface, which is thought to be harmful to the biosphere and to man. The current debate is over whether a decrease of ozone has already taken place; but apart from high latitudes of the Southern Hemisphere (SH), no significant decreases beyond the level of natural variability appear to have taken place anywhere else.

In addition, ultraviolet radiation measured at different sites in the US over the last 15 years has, if anything, decreased - therefore giving no hint in favor of the postulated ozone decrease and the expected UV increase. Furthermore, some scientists question the seriousness of the implications of a 10 to 20 percent UV increase on the biosphere, since - as they argue - natural UV levels increase by a factor of three or four as one moves from higher latitudes towards the equator, and if there is a moderate ozone depletion, one

30 GLOBAL WARMING

would therefore only experience a UV increase comparable to moving a few hundred miles to the south, or closer to the equator.

To return to the CFC's role as greenhouse gases, we should first note that they play such an important role despite their very small concentration in the atmosphere. This is due to their molecular structure and the unfortunate occurrence of a major absorption band right smack in the hole of the atmospheric blanket, so that one kg of CFCs has the greenhouse power of several thousands kg of CO2 (see table 2). On top of this, there is their very rapid increase in the atmosphere (3-5 percent per year) and the very long lifetime of up to over 100 years.

Their contribution - at current emission rates - to the man-made greenhouse effect is of the order of 20-25 percent and is likely to grow.

2.

A Look Ahead - Is The Future Ours To See?

So far we have only been concerned with past and present emission rates and patterns of various greenhouse gases. We have said nothing about the future yet.

But, of course, the future is the key issue. No one would have become upset about past emission rates if he did not expect future emissions to somehow detrimentally affect climate and life.

But here is where life begins to become complicated. All the concerns voiced about the future direction of climatic developments assume, one way or another, that the build-up of greenhouse gases will continue at the same rates as it has up to now, or at least in some worrying way - soon enough and large enough to have a significant adverse impact on climate, which again is thought to occur soon enough, and to be large enough to be a cause of serious concern - making it imperative to take countervailing action in the form of reducing trace-gas emissions now.

So, in our ongoing quest to examine the scientific basis of the greenhouse effect and of the claims about its adverse impact on climate, let us investigate future trace-gas scenarios in an attempt to not only determine whether or not a build-up serious enough to adversely alter our climate will occur, but when it might occur.

The timetable of events has important consequences for the impact of a possible climatic change on nature, and also for the time we have to fight off that change, should we decide to do that.

Obviously, if we expect some detrimental change in, say, 20 years, there is no time to waste, but if that change will not occur for another 100 years, we can afford to ponder its consequences and take some time searching for the best possible way to counter it.

But now, pass the crystal ball please.

Let us first direct our attention to CO2, which plays a central role in the greenhouse debate, and which has been the subject of a large number of studies, all of them attempting to elucidate the way in which CO2 emissions might relate to various future trends. Since CO2 is released largely in energy generating ventures, the debate in the past has been, and in the future will be centered on

32 GLOBAL WARMING

energy policy - the favorite playground of a great number of activists from all political backgrounds. Here, for the first time, linkages become apparent, linkages between climate and energy, which do not seem to have anything to do with each other at first sight, but, as we will see, they are in fact closely related in a multitude of ways.

Before we go into more detail, let us first of all realize that we are skating on very thin ice indeed in everything we are now attempting to do. Every projection into the future, and every assumption about it, is speculation at best in most cases. Any unforeseen future event, whether it is a war, an economic downturn, or a major technological breakthrough, may seriously dent, if not altogether wreck any of the assumptions we will be talking about.

For example, recall how Sheik Yamani, the former Saudi Arab- ian oil minister, extended "present trends" of oil prices into the future, and declared in 1981 that prices could only go up, but instead they only went down from then on out. In 1986, after the almost complete collapse of oil prices, Yamani was fired.

By the same token, just to show that economic forecasts, which more or less form the basis of future energy use patterns, may be even more unreliable than weather forecasts, most "experts" and "analysts" were absolutely certain in the summer of 1987, and publicly said so, that the stock market could only go up; and when it crashed a short while later, again it was the "experts" and "analysts" who predicted a severe economic crisis similar to the one following the 1929 stock market crash - only to witness a mirac- ulous rebound of the Dow Jones in the year after the crash. Ap- parently, even the experts can go wrong at times.

So where do we stand? We should take every projection into the future on a round-trip basis, look for pitfalls, and be prepared to see it peter out altogether if one or more of the assumptions it was built on crumble: Predictions are difficult to make, especially correct ones.

Returning to CO2 emissions, we know that past - and future - emission patterns depend on a roster of determinants. The most important ones are:

• Population growth • Economic growth • Energy use growth • Energy use patterns


Once more we begin to appreciate the scope and the possible impact the climatic change debate has on our lives. Since the emission of CO2, the major greenhouse gas, is so closely related to our most basic activities, it seems almost inconceivable to curtail, let alone cease, any of those CO2 emitting activities.

The first of these factors, population growth, will be the decisive one in the LDCs in coming decades - coupled with economic growth.

Current CO2 emissions in the LDCs are about one fifth of what they are in the industrialized countries (and per capita emissions are much lower). If we assume that population will increase over the next 50 years at an average annual rate of two percent, the average of the last 20 years, and if we assume per capita emissions will remain constant, then total CO2 emissions from the LDCs will more than double.

It is almost certainly foolish, however, to assume that per capita emissions will be constant, since LDC economies can be expected to be the fastest growing ones. Without nuclear energy this economic growth will be based mainly on the use of fossil fuels. As- suming then an average economic growth rate of three percent per year, again a moderate figure, which would translate into a 1 percent per year per capita growth rate, and furthermore assume that the amount of CO2 released per unit of GDP remains constant, CO2 emissions in 50 years would more than quadruple. Again, this seems to be a moderate estimate: a simple extrapolation of post WW II trends, 6.3 percent per year, would result in a staggering twentyfold increase. Even in that case, per capita emissions in some LDCs would still be lower than what they are today in the industrialized countries.

Perhaps we can now begin to appreciate the second issue inter- mingled with the climatic change debate: the income inequalities between North and South.

In order to overcome those inequalities, the South - the LDCs - will have to grow its way out of backwardness, which requires the expanded use of fossil fuels.

Population growth in the industrialized countries has been far more moderate and has halted altogether in some countries. Thus the future contribution to CO2 emissions from an increase in population there will probably be quite small compared to what it will be in the LDCs.

On the other hand, economic growth will continue in all likelihood. Let us assume an average economic growth of 2 percent

34 GLOBAL WARMING

per year. This is a very moderate figure, but a reasonable one, because it is less than the heady growth rates of the post war years, but more than during the tough economic times of the 70s and '80s. Under such assumptions, CO2 emissions will more than double, also assuming no change in fuel use.

As we have already seen (page 19-21), however, economic growth and energy use have begun to become decoupled in the wake of the traumatic experiences of the energy crises of the '70s. Today, less energy, notably fossil energy, is used to produce a unit of GDP than was needed in the early 70s. This fact is aptly demonstrated in Table 7, which shows the increase in levels of efficiency of energy use in various countries, where — is it any surprise? — Japan again takes the lead. But the other industrialized countries did not fare so badly, either.

Despite the growth in the economies of the industrialized countries of 60 percent there was no corresponding increase in energy consumption due to increased energy efficiency and the structural changes toward the service economy, not only in the U.S.

In other words, we now emit only 20 percent more CO2 than in the early 70s, although GDP has grown by roughly 60 percent. If we now assume that the industrialized countries will be able to maintain that pace in energy efficiency increase over the next 50 years, as difficult and as questionable as that may be, because we are now in a less favorable position in the learning curve, CO2

emissions in our 2 percent economic growth scenario would increase at approximately 0.7 percent per year and by a total of about 40 percent, despite a concurrent two and a half fold increase in GDP.

Let us now furthermore assume that some, but not all of that energy efficiency increase will be implemented in the faster growing LDC economies, which should be given more latitude in energy use because they are starting from a lower level. If we take the fraction of efficiency increase to be one third of the economic growth rate of 3 percent, i.e. 1.0 percent, CO2 emissions would grow at 2.0 percent, and then go up two and a half fold in 50 years. We thus partition the efficieny increase in the following crude manner: there is no efficiency increase in the first 25 years, i.e., CO2 emissions would grow at the economic growth rate, which makes some sense, because during the first stages of industrialization, there is a tendency to use more energy per unit of GDP than during pre-industrialization. In the later stages of industrialization, CO2 emissions are assumed to grow at one third the eco-


nomic growth rate, i.e., 1 percent. Combining the emissions from the industrialized countries and

from the LDCs 50 years from now, we obtain an annual emission rate of roughly 10 billion tons of carbon.

This is a very simple scenario, which is of course subject to all the caveats and uncertainties mentioned at the beginning. Still it may not be too far off the mark: it is in fact right in the middle of a number of recent estimates, the bandwidth of which can be gleaned from Fig 5.

These scenarios, and ours as well, which includes a fair amount of energy efficiency increase, would indicate approximately double today's emission rate. This is seriously at odds with recent calls for a 20 or even 50 percent reduction in CO2 emissions, given the fact that the use of fossil fuels, rightly or wrongly, assumes such a central role in the economies around the world, and that no suitable replacement is presently in sight.

Therefore, if the proposed 20 percent reductions were mandatory, it seems likely that the world would basically be confronted with either one or both of two drastic consequences: First, in the industrialized countries, a drastic reduction in living standards through curbed economic growth; and second, a drastic reduction in population growth in the LDCs, since a denial of economic growth to the LDCs amounts to exactly that.

To what extent the industrialized countries can be forced to sacrifice their living standard and the LDCs their population growth in the name of a perceived threat to climate - the reality of which is still to be assessed - remains to be seen.

We will not discuss the need to actually employ reduction meas-

Table 7: Trends of energy intensity in some OECD countries between 1970 and 1987 (1970 = 100).

1970 1975 1980 1987 1970* 1985*

FRG 100 91 89 79 0.38 0.31

Japan 100 96 85 68 0.40 0.29 USA 100 95 89 73 0.76 0.57 OECD 100 94 89 77 0.55 0.43

* tons of oil equialent per 1.000 US$ (1980) GDP

Source: After OECD.

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ures along with possible ways to achieve this now, but leave the discussion of that for a later chapter.

In any case, we have analyzed a possible scenario of future fossil fuel use, which yielded future emission rates right in the middle of a variety of diverse scenarios. This scenario may therefore be considered a middle-of-the-road-most-likely and non-extreme projection. It leads us to a probable or most likely average CO2 emission growth rate of 1 to 1.5 percent per year over the next 50 years.

It should be remembered that this estimate already incorporates a good margin of increased efficiency of energy use, which was forced upon us, at high social costs, by two energy crises in the 1970s, and which has essentially been extrapolated 50 years into the future. This scenario may therefore be somewhat biased towards the low end, since average growth rates in the 1970s and 1980s were somewhat higher, even if we include the "slow" period of the two energy crises. Even then, it only serves to empha- size a point made above: even if we adopt a cautious scenario about future economic and population growth, CO2 emissions - barring some major unforeseen events - could easily double within the next 50 years. This assessment is underlined by the fact that CO2 emissions went up by 20 percent since the last world-wide recession in 1982 alone.

The Intergovernmental Panel on Climate Change (IPCC) arrived at a similar conclusion in their "Business as usual" (BaU) scenarios, which assume a CO2 growth rate of about 1.8 per cent per year (see Fig. 6). Our emissions estimate therefore falls about halfway between the BaU and the increased energy efficiency "B" scenario and might thus not be too unrealistic.

The Role Of The Biosphere In Future CO2 Emissions

There is one additional uncertainty we have not addressed so far, and which could make a large difference in future CO2 emissions and atmospheric concentrations, release of CO2 from biomass burning, especially in the tropics. It currently adds another 2 - 4 Gt to the 6 Gt from fossil fuel use. The net emission from the biosphere is shown in Fig. 3 and Tab. 3. The net emission is less than the gross release from the tropics because of regrowth in other regions of the world. If present rates of deforestation continue, there will not be much left of tropical forests in the not too dist- ant future. That would be a significant addition to the atmos-

Figure 5. Scenarios of future trends in CO2 emissions. The lettering of individual curves denotes the projections of various scientific groups. Source: Oak Ridge National Laboratory, 1984.

pheric CO2 load. If, on the other hand, attempts to curb deforestation are succesful, atmospheric CO2 increases could certainly be reduced.

This would particularly be true if some recent suggestions turn out to be correct, that the tropical biospheric source might be of the order of 4 Gt, and that a CO2 sink of similar magnitude exists in mid-latitudes of the Northern Hemisphere. In that case, cessation of biomass burning would reduce the emissions by 4 Gt. That would enable the mid-latitude sink of 4 Gt and an additional sink in the tropics, due to re-growth there, to act on fossil fuel CO2

emissions, thereby significantly reducing the speed of an atmospheric CO2 increase. Even under a scenario of a smaller and possibly more realistic mid-latitude biospheric sink of about 2 Gt, and less release in the tropics, cessation of biomass burning would indeed make a very significant contribution to lowering the rate of atmospheric CO2 increase.

How Much Fuel Is There To Burn?

Looking even further ahead, as an afterthought we will now address an assumption usually made without any questions in the CO2 and climate debate, namely that there are sufficient amounts


38 GLOBAL WARMING

of fossil fuels to double atmospheric CO2. A little later on we will analyze climate-model predictions

based on the hypothesis that the atmosphere contains twice the present amount of CO2. Most of the climate projections use those 2-times-CO2 scenarios as a benchmark. Most of the dire predictions we hear so much about are based exactly on those 2-times- CO2 scenarios (or an increase of the other trace-gases to such an extent that the effects are those of a CO2 doubling). It therefore appears appropriate to analyze the circumstances under which such a doubling might occur.

As a first step, we will determine whether there are in fact sufficient fossil fuel reserves to bring about such a doubling. To the surprise of no one, the estimates on fossil fuel resources are con- stantly being revised, and mostly, to the relief of an energy hungry world, upwards. For instance, there has been talk for about 20 years now that the world is going to run out of natural resources very soon. The infamous "Club of Rome" made a name for itself by scaring the world with doomsday scenarios back in 1972. Well, in a finite system they are right: in such a system, nothing can grow forever, least of all at an exponential rate, as the economy and world population have in recent decades. Then again the "finite" resource base of the wood-burning economy of earlier centuries was superceded by the introduction of coal, which was superceded by oil and so on.

And their timetable appears to have been somehow out of line. A good case in point is the extent to which our oil reserves were supposed to last. Over the past few decades the estimates have hovered around 40 years. In other words, despite the fact that we have been using oil all this time, and in fact should have run out by now, we still have 40 years to go, which is of course due to the constant discoveries of new oil and improvements in extraction technologies which have led to an upward revision in oil reserve estimates.

Most of the oil companies and institutions, such as the Internat- ional Energy Agency (IEA) and the World Energy Conference (WEC), spend a lot of time and effort keeping track of the fossil energy we may still have left to burn.

In terms of carbon, which is what we are interested in, the bottom line is that there are approximately 750 billion tons in what is generally referred to as "proven recoverable reserves". This means that geologists and geophysicists have actually "seen" it on their various devices used to "look" into the earth, and that pre-


Figure 6. Projected atmospheric concentrations of C02, CH4 and CFC-11 resulting from the four IPCC emissions scenarios. Source: IPCC, 1990.

40 GLOBAL WARMING

sent existing technology is able to extract the fuel from the earth. In addition, there are those "resources" which geologists

"think", "expect" or somehow "estimate" to be there on the basis of a variety of factors, such as geology similar to known deposits. Those resources are obviously much more speculative in nature and amount to 2000 billion tons or thereabouts. The geological deposits of fossil fuel are several times larger than even this figure, but the trouble is that they cannot be extracted from the earth by known technological means at a reasonable cost.

Now, the atmospheric content of carbon dioxide is 350ppm (see table 1), which, in tons of carbon, is about 720 billion tons. So, at first sight it looks easy to double the atmospheric content even if only the proved recoverable reserves are used. But there is a difference between what we emit into the atmosphere and what remains in it as atmospheric concentration.

This fraction, called the airborne fraction, has only been in the neighborhood of 50 percent of the amount released by fossil fuel burning over the last few decades. Since the clearing of forests added another 1.5-2 billion tons of carbon to total emissions, the actual airborne fraction is accordingly even lower than that. In other words, less than half of what we put into the atmosphere remains there. One way or the other, the rest is incorporated into various compartments of the so-called global carbon cycle, which plays a very important role for life on earth, and which we will analyze in more detail later on. At this point, suffice it to say that the "missing carbon" is taken up by (1) the oceans and (2) the terrestrial biosphere.

Therefore, even if we burned all the known "proven recoverable reserves" of fossil fuels, we would not be able to double the atmospheric CO2 content, since one half of 750 is 375, which would then only be enough to increase the atmospheric CO2 content by 50 percent or so.

Only if we resort to the "additional estimated resources" will we be able to double the atmosphere's CO2 hands down. But again, that assumption involves considerable uncertainty as to when and under which economic and technological conditions the recovery of these additional estimated resources will be attempted. If it is more expensive to dig that fuel out of the earth than to use alternative energy sources, such as solar energy, nobody will attempt to recover these fossil fuels anymore.

This may easily be the case in a few decades from now when the recovery of the additional resources may become necessary to


meet the world's energy needs. Therefore, the prohibitive cost of extracting fossil fuel from the earth may, sometime in the future, cause a shift in energy use from fossil to solar or hydrogen, which are too expensive at current prices and current technology. A technological breakthrough in cold fusion or hot fusion technology might do the same much earlier - putting an end to the fossil age and the emission of CO2 into the atmosphere.

Those little examples show that we have to be careful when we make assumptions about future energy use, in particular fossil energy use, and the resulting CO2 emissions.

On the other hand, it also shows that there may indeed be limits to fossil fuel supplies and that it is a good idea to use them rather carefully: At the current rate of consumption, 6 billion tons per year, the proven recoverable reserves will be exhausted in 120 to 130 years - and even faster if allowance is made for the increasing fossil fuel use in coming decades.

Consequently, we do not conclude that it is impossible to double the atmospheric CO2 content; we merely wish to point out where the limits to such an increase might be.

The Crystal Ball: Next Act, Methane

We next take a look at methane. The reasons for its increase are somewhat obscure, as we pointed out above. Its increase appears to show a fairly close correlation with the overall increase in world population. For lack of a better estimate, most scientists continue to link it to the growth in population, which has been and will probably continue to be about 1.5 percent a year. In 50 years then, the atmospheric concentration of methane would roughly double and reach 3.2 ppm. This corresponds very closely to the the IPCC BaU-scenario (see Fig. 6). Therefore, the relative importance of methane as a greenhouse gas will continue to grow.

Next: N2O

The crystal ball becomes even hazier when it comes to N2O, which luckily is not such an important greenhouse gas. For lack of a better estimate, the past increase of 0.25 percent per year is again extrapolated 50 years into the future, which results in an increase of between 10 and 20 percent.

42 GLOBAL WARMING

No End In Sight: Ozone

The picture becomes even worse with ozone. As we pointed out above, its contribution to global warming presumably is two-fold: First, through an increase in short-wave solar radiation due to stratospheric ozone depletion, and second, through an increase in the greenhouse effect resulting from increasing tropospheric concentrations of ozone.

Obviously then, turning to the first point, if ozone depletion does not progress at the rates feared by many, and if recent efforts to ban CFCs (the depletion causing agent, see above) are indeed successful, the increase in short-wave radiation would also not occur - or not to the extent feared.

Turning to the second point, tropospheric ozone increase in the last decade and a half has had a somewhat spotty and uneven pattern, making it doubtful whether a global trend really exists.

One of the reasons for this is that almost all reliable ozone measurements which show an increase are from either Europe or North America - which casts serious doubts on the global validity of any such trends because they are undoubtedly contaminated by regional emissions of ozone pre-cursors not found in more remote areas. In the US and Europe, except for some urban areas, there is no significant trend in surface ozone over the last 10 to 15 years. There are some claims that global tropospheric ozone concentration has doubled over the last 100 years. But such claims must be viewed with caution, since ozone concentrations in relatively populated areas last century (from which we do have some data) could not have been decisively lower than the concentrations in today's ultra clean areas for a variety of reasons related to atmospheric chemistry. For the most part, ozone could not have increased by very much in the last century. Therefore, claims that ozone will go up by 50 percent or so over the next 50 years should also be taken with a grain of salt.

Moreover, even if it were to increase, it would be difficult to combat it - as local administrators of a number of large urban areas in the US, particularly in southern California, have painfully found out in recent years. There is no easy, clear-cut solution to the problem of tropospheric ozone increase.

The problem is compounded by the quizzical fact that a reduction strategy which might work on a local and urban level might not work at all on a regional or global scale - and vice versa. This is due to the complex chemistry of tropospheric ozone formation,


which is not yet fully understood. All that we can say at present is that, in all likelihood, a reduction of nitrous oxide emissions from fossil fuel burning may curb a global ozone increase. But in most of the industrialized countries, laws already exist to limit nitrous oxide emissions from a variety of sources. It is therefore rather difficult to assess future trends of ozone, only that it appears to be less than a suspected 50 percent increase over the next 50 years.

This assessment is supported by recent model calculations, which arrive at a global tropospheric ozone increase of only 10-20 percent by 2020, making an increase of only 30 percent over a 50 year period more likely. We therefore tentatively assign an increase of 30 percent to the next five decades, keeeping in mind that no sufficiently sound scientific basis currently exists to justify either a number of 50 percent or, say, 10 percent; so we should tentatively stick to model calculations which appear to be at least somehwat reasonable.

Ozone essentially represents a riddle yet to be solved, and it would not be surprising if those numbers changed drastically in the years ahead.

This completes the first round of crystal ball gazing — on a somewhat unsatisfactory final note.

Last Act: The CFCs

This brings us to the second round, in which we assess future trends of the "industrial" substances, the CFCs. We will restrict our deliberations largely to CFC-11 and CFC-12, the two main ones. It may be noted in passing that other CFC compounds, which occur in much smaller concentrations, may gain in impact in coming decades.

At an estimated present contribution to the man-made greenhouse effect of 20-25 percent, the CFCs are the second most important class of trace-gases thought to affect the climate. Underli- ning their particular importance to the greenhouse debate is their meteoric atmospheric growth rate of about 3-5 percent, compared to 0.4-0.5 percent for CO2.

Were those growth rates to continue unchecked, the CFC concentrations would grow rapidly, and in only a few decades they would become the most important greenhouse gas, eclipsing CO2

in importance. Indeed, part of the recent concern over the trace-gas build-up,

44 GLOBAL WARMING

and the possibly ensuing changes in the climate, is due precisely to the realization that not only does CO2 behave as a greenhouse gas, but other gases do so as well, gases whose atmospheric abundance is increasing much faster than CO2's. This moves up the timetable: we see climatic warming approaching much faster than had been expected. That is, the effects we expected to see due to an increase in CO2 alone in, say, 2050, have now been moved up to 2020-2030 or thereabouts.

However, as we saw a little while ago, the CFCs not only act as a greenhouse gas; they may have a deleterious effect on stratospheric ozone as well.

To counter their role in the ozone depletion process, regulatory action - pioneered by the US in the 1970s - has already been taken in a number of countries - with the inadvertant, but most welcome, side-effect of also countering the man-made greenhouse effect.

Even more radical reductions are likely as a result of the "Mon- treal Protocol", in which the signatory countries agreed upon a 30 percent reduction of CFC emissions, not to mention the "Helsinki Declaration" in 1989, where some countries agreed on a complete phase-out of CFCs by the year 2000. In fact, the phase-out club is growing steadily, and the end of the "traditional" CFCs may be in sight in the next 10-15 years. Clearly, much regulatory action is still pending and may greatly influence future concentration of CFCs, but it seems nevertheless likely that CFCs will not continue to increase at past rates of 3-5 percent per year for the next five decades; instead, those rates will continuously decline, may even become negative, and the atmospheric concentration might actually decline - possibly early next century. It may be pointed out that the absolute concentration will continue to increase as long as the source of those gases is stronger than their removal mechanism.

The problem is somewhat compounded by the fact that a large amount of CFCs are still "slumbering" in appliances, i.e., refrige- rators and air-conditioners currently still in use, which may eventually release their CFC into the atmosphere after the life of those appliances has run out - and after there may have been a general, world-wide ban on CFC use. Accordingly, even after taking various reduction plans into account, there still remains a wide scatter in estimates on future CFC trends.

When considering various scenarios for the next 50 years, an average growth rate of 1.5 percent may be a reasonable estimate that straddles a higher growth rate of close to 3 percent in the early


decades and a growth rate of near zero - or less than zero - in the later ones. This scenario would then be between "B" and "C,D" of the IPCC (see Fig.6).

We are now in a position to give a tentative trace-gas scenario for the next 50 years, which, like any other scenario, has to be taken with a fair amount of caution; nonetheless, a good case can be made that it represents a reasonable consensus view, which avoids extremes in either direction:

CO2: 1.0 -1.5 (Emission rate) CH4: 1.5 N9O: 0.25

O3: 0.5 CFCs: 1.5

We note that for CO2 the rate of increase is given for emissions, while for the other trace-gases, it is given in actual atmospheric concentration, for the following reason. As we shall see shortly, the actual rate of atmospheric increase of CO2, the most important greenhouse gas, depends on various interactions within the carbon cycle, which we will investigate prior to assigning a likely atmospheric rate of increase for CO2. We also note that the rate of increase of the CFCs, the second most important greenhouse gas, has been trimmed from 3-5 percent to 1.5 percent.

To get a feeling for the importance of that modification, let us consider the total change in concentration after 50 years. In a 4 percent scenario, it would be over seven times of what it is today, whereas in the 1.5 percent scenario it would roughly double.

Obviously, the regulatory action taken against the CFCs because of their suspected role in ozone depletion will also have a pronounced impact on their role as greenhouse gases, and therefore constitutes a major move to thwart the greenhouse effect as well. It appears then as if the time-table of all those dire predictions has been moved farther into the future by quite a few years.

Is there some relief from the sweat box after all?

3.

On The Threshold To Climate Modeling: The Carbon Cycle

So far in our quest to examine the scientific basis of the greenhouse effect and the predictions of future global warming, we have achieved the following: 1.We have found out what the greenhouse effect is - both natural

and man-made; 2. Found out which trace-gases and human activities contribute

to it; and 3. with a lot of if's, did some crystal-ball gazing and attempted to

find out what the future concentration of those gases might be. Our next step now will be to assess in which way the climate

might change if the trace-gases do increase in the suggested manner. The climatic changes we will be talking about are "what if" scenarios. In other words, we will be considering changes which might occur, if trace-gases increase in the manner and to the extent assumed by the climate-model predictions.

This is where the infamous "if present trends continue" enters the game once again.

And we also draw closer to the central issues of the debate, i.e., climate predictions. No one would have become upset about trace-gas increases as such, which is all we have discussed so far, if it had not been for those dire climate predictions which stirred up a storm. Consequently, one of our major endeavors will be to examine those climate predictions: only if there is reason to believe that they are correct, is the concern about increases of trace- gases justified.

Before we actually embark on a journey through the wonderland of climate prediction, there is still one job left to do from the preceding chapter: We will examine what happens to CO2 once it has been injected into the atmosphere by one or another carbon- burning process.

The Carbon Cycle: Welcome To Life On Earth...

Many people may actually be very surprised to hear that car-

bon dioxide, which sounds so much like the air pollutant "sulfur


dioxide" or "nitrogen dioxide" is not a pollutant at all. Instead, it is a substance without which life on earth as we know it would not be possible. Carbon dioxide, and more generally, carbon, is continuously cycled through nature and it is reflected in facet of life on earth. In fact, it is the very building block of life. No plant life, no animal life, including human life, would be possible were it not for carbon dioxide. As you are sitting here reading this book, you breathe, and as you breathe you exhale carbon dioxide, which your body produces while oxidizing carbon compounds contained in the food you ate earlier in the day. And while humans beings emit - breathe out - CO2 just as a motor vehicle does when it burns gasoline, nature, - trees, flowers, corn fields - take it in through a process called photosynthesis, in which plants breathe in CO2, take the carbon out of the carbon dioxide, use it to build stems, twigs, branches, leaves, blossoms; in turn they emit oxygen into the environment and therefore give it back to us. But human beings, in turn, use those plants, - tomatoes, apples, water melons - they eat them and burn the carbon contained in them during the metabolic process - breathing out CO2.

This is a very simple, but nevertheless illustrative example of a carbon sub-cycle. There are many more of those cycles which link up to what is called the "global carbon cycle".

Let us pause momentarily and consider this cycle one more time. If the carbon dioxide we emit by breathing, driving to work and heating our apartments is taken up by plants, in fact is necessary for them to thrive, how can it be that carbon dioxide got such a bad reputation recently? If it is that good for the biosphere, shouldn't we be putting more of it into the atmosphere to make plants grow better? Moreover, would that not possibly solve some of the envisioned future food production problems in some parts of the world? As we shall see in a little while, there is - as one of the biggest ironies in the trace-gas/climatic change debate - an almost unconditional yes to those questions.

But the problem now at hand is that more CO2 enters the atmosphere than our biosphere can handle at the present time. In addition, the biosphere is being continuously destroyed by deforestation and changing land use patterns, particularly in the tropics, thereby reducing the base which can swallow excess CO2. On the other hand, it has been suggested that the biosphere in mid- latitudes of the Northern Hemisphere has been expanding in recent decades - swallowing increasing amounts of CO2.

Moreover, what remains of the biosphere does respond to what

48 GLOBAL WARMING

is called CO2 fertilization, i.e., the increased production of biomass through increased levels of CO2 in the atmosphere. Some scientists think that this process, which is easy to demonstrate in experimental set-ups, has in fact already occurred in nature, and can be deduced from the increasing amplitude in the wiggles in the curve in Fig. 7, the curve showing the atmospheric carbon dioxide increase: Whenever the biosphere takes a deeper breath, those wiggles grow larger.

However, much of the carbon taken up by plant tissue and fixed to them in summer, is re-emitted into the atmosphere when leaves fall off a tree, or when herbacious plants die and begin to rot. Rot- ting means bacterial decay in which CO2 is produced and recycl- ed into the atmosphere.

Some of the carbon is incorporated into the woody tissue of trees and may stay there, not only for years and decades, but for centuries and millenia, because that is how long some trees live. Therefore, trees and other woody plants provide what is called a "sink" in the carbon cycle as opposed to sources like burning of fossil fuels and deforestation, microbial decay of leaves and other organic matter.

But the relationship of the sink of CO2 fixation to woody tissues is at present neither large enough to completely counterbalance the source of fossil-fuel derived CO2, nor to even explain why only half of it appears in the atmosphere. But if the biosphere does not provide a sink large enough to account for the "missing carbon"- on the contrary, at present it is a source, and probably has been for some decades - where does the carbon go?

Enter the oceans. They cover nearly three forths of the earth and we may sometimes have the impression that it hardly matters what happens on land, in terms of the carbon cycle and many other geological and chemical cycles, but also with respect to climate, as we shall see.

The oceans play a key role in the global carbon cycle. They take up CO2, put it into solution and make it available to a number of physical, chemical, and biological processes.

Physically, carbon may be transported horizontally and verti- cally by ocean currents. We know from observations and modeling studies that CO2 is primarily taken up by the oceans at high latitudes and transported downwards and toward the equator. Chemically, it interacts with calcium carbonate, the material sea- shells are made of. Biologically, it is used to form plankton, which eventually sinks to the sea floor, thereby removing carbon from


the ocean surface. All these processes combined remove carbon from the atmosphere and provide the biggest sink for carbon. But it still is not enough to balance the carbon budget, because, as we know, atmospheric carbon is increasing.

Much the same as in the biosphere, but on a larger scale, the ability of the oceans to curb the increase of atmospheric carbon depends on the rate - or speed - at which it is injected into the atmosphere and made available to the oceans. If the capability of the oceans to swallow CO2 is less than the rate at which it is emitted into the atmosphere, the oceans can not take it up and atmospheric concentrations will increase at a rate dependent on the emission rate in a way illustrated in Fig. 8.

Fig. 8 presents results from model calculations incorporating physical and chemical, but no biological processes in the oceans. The interesting aspect of Fig. 8 is that the rate of atmospheric increase slows dramatically as the input rate moves from 2 percent to 0 percent, i.e. constant emissions, but changes only very little as we move from a constant rate to a negative growth rate, in other words a reduced emissions scenario.

Now, we recall from the previous chapter that our estimated emissions growth rate for the next 50 years was between 1 and 1.5 percent, and we are therefore right in the middle of that territory of fig. 8 where large variations in the atmospheric concentration can be expected as a function of the input rate. Therefore, the future atmospheric CO2 concentration will very critically depend on whether emissions grow at, say, 1 or 2 percent.

If we then apply our 1-1.5 percent scenario to Fig. 8, a doubling of CO2 would not occur in the foreseeable future, but sometime in the early 22nd century. In a constant emission (no growth scenario), doubling would occur around the year 2300 and in a 2.3 percent scenario, near the middle of next century, as many assume.

Interestingly though, the 1-1.5 percent scenario would then approximately translate into a 0.5 percent atmospheric growth rate - approximately a continuation of "present trends" - present meaning the last 20 years. Referring once again to the IPCC scenarios, we would not be somewhere in the middle between scenarios "A" and "B" after 50 years, but closer to "B" than envisioned before (see Fig. 6). It should be recalled, however, that the ocean's bio- logy, which may further dampen and slow down, is not yet included in these calculations. Likewise, the terrestrial biosphere is also not accounted for - which might act as a considerable sink. We may therefore conclude that even though CO2 emissions from fos-

50 GLOBAL WARMING

Figure 7. Historic CO2 concentrations observed at Mauna Loa, Hawaii. SOURCE: U.S. Department of Energy, Report DOE/FE-0164.

sil fuel burning will continue to grow, the likelihood of a rapid and dramatic CO2 build-up is smaller than previously thought, particularly if biomass burning has been a relatively large source in the past and will be curbed in the future: a conclusion, which has obvious ramifications concerning the time frame and the magnitude of a possible greenhouse warming. We recall that the magnitude and time frame of a greenhouse warming had to be altered once before by the less than expected rate of increase of the second most important greenhouse gases, the CFCs. Recalling the IPCC scenarios, where we would now be closer to "B" on CO2, between "B" and "C, D" on the CFCs and on "A" with Methane plus a small contribution from Ozone, we might expect to end up closer to "B" than to "A" as a rough estimate (see Fig. 6).

This is because CO2 will remain the predominent greenhouse gas and large increases of methane will be balanced somewhat by smaller increases of the CFCs, which are potentially more powerful greenhouse gases.

We may then ask again: Could it be that all those horrific impacts on climate which we still have to assess, if they really occur at all, would not occur as soon as a lot of people claim, but much


farther down the line, possibly giving us much more time to either combat them or adjust to them, and thereby take the tone of ur- gency out of the voiced concerns? According to everything we have heard so far, the answer can only be yes.

Let us now return to CO2 and analyze one aspect of an atmospheric CO2 increase which is frequently overlooked altogether or only dealt with in passing, but which we have briefly touched on a little earlier, namely the impact on the biosphere.

CO2 does assume a special role indeed, since, in contrast to all other trace-gases emitted from fossil fuel burning, it is not a pollutant with potential detrimental effects on the biosphere such as SO2 or acid rain, or photochemical oxidants, but a gas essential and beneficial to the thriving of our biosphere.

Therefore, by emitting CO2 into the environment, man is not harming it, but rather benefitting it, certainly over any CO2 range that might possibly occur as a result of continuing fossil fuel burning.

This is a fact which many people have a hard time grappling with, especially since it has been engrained in people's minds that man's actions could only harm the environment. This one-sided doomsday view of the world is particularly prevalent among those who, because of their ideological position, maintain that any change, as long as it is man induced, is bad per se and ought to be resisted. Surely, this is a philosophical point and has nothing whatsoever to do with the relevant science. Since we are concerned with the scientific basis of the greenhouse effect and matters related to it, we will not dwell on those philosophical aspects but rather return to science and present an image of the biosphere the way it may evolve under increasing CO2 concentrations.

There are in fact a large number of studies which have attempted to evaluate the possible impact of an enhanced CO2 level on a variety of plants, both natural and cultivated.

The general conclusion of those studies is overwhelmingly positive on CO2 and may be summarized as follows:

Increasing CO2 levels lead to increases in photosynthesis, plant weight, plant branch numbers, fruit numbers, fruit size, plant tol- erance of atmospheric pollution and plant water use efficiency.

While the first factors simply reflect CO2's role as a fertilizer, the last two factors are related to the way a plant operates. It breathes through tiny openings in its leaves, called the stomatae, which may open or close depending on the environmental conditions. Increased CO2 acts as an anti-transpirant, causing the stomata

52 GLOBAL WARMING

openings to close partly and take in less air pollutants and lose less water through transpiration, factors which may be important under drier, but CO2 enriched conditions.

Those positive effects may not be as large though, if other nu- trients such as nitrogen or phosphorous are in insufficient supply. But curiously enough, nitrogen has not been a limiting factor in recent decades - at least not in the more industralized regions of the Northern Hemisphere. This is because nitrogen emissions are another by-product of fossil fuel burning; and even though nitrogen emissions are considered air pollutants, they do have a ferti- lizing effect on plants, and therefore add to the general stimulus given to plants by the increasing level of CO2.

Some scientists claim that weeds may grow better under a high CO2 scenario at the expense of agricultural plants, thereby nullifying - at least partly - the expected positive impact on plant growth. The final vote on this has not yet been cast, but as far as trees are concerned, there is growing evidence that they tend to reap a particularly rich CO2-bonus, since they accumulate carbon and grow bigger year after year - which weeds do not do, since they are mostly annuals.

Furthermore, when the additional impact of higher temperatures is taken into account, which is expected to occur as a result of an increase in the greenhouse effect, it is sometimes claimed that plant diseases may increase and adversely affect any potential gain from a CO2 enriched atmosphere.

Here, another factor comes on stage, namely the impact of higher temperatures on plant growth. We are not yet in a position to determine exactly what higher temperatures may result from the additional greenhouse effect, but we may take a quick glance at existing experimental work that has been conducted to investigate relationships between plant growth at high CO2 scenarios as a function of temperature (see Fig. 9). Does it really come as a surprise that the higher the temperatures, the higher the growth benefits, at least over the range of temperatures observed on earth. Remarkably, this is even true for tropical temperatures and it partially reflects the fact that the species variety of the biosphere increases as temperature and moisture increase. This point will be taken up later on, when we assess the possible impact of a climate change on nature, the environment, and human activities.

After examining possible future trace-gas scenarios and various ways carbon dioxide may interact with our natural chemical and biological cycles, and trying to determine how soon a dramatic


Figure 8. Growth of atmospheric C02 concentration as a function of the emissions growth rate. Source: Maier-Reimer and Hasselmann, Climate Dynamics, 1987.

build-up of greenhouse gas may occur in the atmosphere, we have found out that the very rapid build-up feared not so long ago may not materialize, because we now know that the main greenhouse gases, CO2 and the CFCs will in all likelihood grow much slower than was projected so far. In the case of CO2, this is due to a re- analysis of future energy use scenarios, but also to newer modeling work which explains the absorbing role of the oceans under different CO2 emission scenarios and, in the case of CFCs, it is the regulatory action taken against them because of their role in stratospheric ozone depletion. This action has the double benefit of also containing the greenhouse effect. Looking again at the IPCC scenarios, our "BaU" scenario would then be lower than theirs.

Computer Wonderland: Welcome To The World Of Climate Modeling

We have now found out how trace-gas concentrations may evolve in the atmosphere, and have therefore laid the ground- work to address the central issue of the current greenhouse debate: What will happen to climate if the greenhouse gas build-up continues? Do we already see some effects due to the greenhouse gas build-up which has already taken place?

54 GLOBAL WARMING

In this debate, the ability of computer climate models to predict future climate changes resulting from increased trace-gas levels takes center stage.

Everything we have heard so far in the media about detrimental climate changes thought to occur from increased trace-gas levels is based on computer model calculations which currently provide the best possible means to estimate future climate changes.

Those computer models were developed over the past few decades to varying degrees of sophistication.

To give you a little bit of detail, there are three major types of models: First, the so-called energy balance models, EBMs, which only consider surface energy fluxes; then second, RCMs, radiative convective models, which also take account of convective air exchange with the atmosphere above a surface point; and finally, the GCMs, general circulation models, which are the ultimate in sophistication and include everything from air currents at various levels in the atmosphere to moisture flow, cloud formation, rain, snow, evaporation, sometimes even the oceans and seasonal and diurnal cycles, in short, the whole works. All of the research we will be considering here, and which is of any relevance to the debate, is based on GCM results. Those models are in fact very similar to the ones used by the Weather Service to compute forecasts for the next weekend, but are extended to include processes which do not have a bearing on tomorrow's weather, but are critically important to climate. Those processes are, of course, the changing composition of the atmosphere and the resultant change in radiative energy, but also exchanges with the surface, such as evaporation.

To make one thing clear, however: no matter how good those models are, they are still only models, incomplete approximations of the multitude of physical, chemical, and even biological processes which take place on earth, and they are currently far from including all processes which may be important to climate. For one thing, we do not even know what they are, and some of the ones we do know about are not yet incorporated into the models because of a variety of computational constraints.

On a forecasting level, we learn to appreciate this every once in a while when a weather forecast, based on computer models, goes bust and instead of sunshine, we have rain on a weekend.

Clearly then, in all types of computer-based weather and climate forecasts there is considerable room for improvement.

Now, a climate "forecast" is achieved by letting the model run


not only for the next weekend but straight out for the next 30 or 50 years.

Let us digress for a moment and define what "climate" is. Cli- mate is the average state of the atmosphere and of such parameters as temperature or precipitation, but also the variability and the range of those parameters over an extended period of time. It can be defined for any given location or larger geographical areas. The time period chosen for defining those averages is usually 30 years, but no less than 20 years. When using the term "climate", it is implicitly assumed that climate does not change very much from one 30-year-period to the next, in other words, climate is somewhat of a constant. This in itself is an assumption of limited validity, as we will see later on, because climate thus defined is indeed continuously changing at time scales ranging from several decades to centuries and millenia.

Figure 9. The influence of ambient air temperature on plants growing in a C02 enriched atmosphere (300 ppm higher than present levels, corresponding to a C02 doubling). The growth modification factor indicates how growth rates vary compared to the present C02 concentration at a given temperature. Source: Idso et al., 1989; in CDIAC Communications.

56 GLOBAL WARMING

A change of climate would be a permanent change in a climate parameter from one 30-year-period - or an average over a number of such periods - to the following 30-year periods, where the change is of sufficient magnitude to be characterized as such.

This magnitude depends on the natural variability of the parameter. Therefore, if there is a run of seasons or years much shorter than 30 years, which is colder or warmer, rainier or drier than the 30 year average, we do not speak of a climate change yet, but rather of short-term climatic fluctuations.

Consequently, the occurrence of a run of extremely cold winters in the late 70s constituted a climate change as little as the string of extremely hot and dry summers in the '30s, because climate did subsequently return to its long-term norms. The droughts of the '30s and the cold winters of the late '70s are true examples of short-term climatic variations.

The climate models and the greenhouse debate then are not concerned with those short-term climate variations, but rather with long-term, lasting changes which occur on time scales of a number of decades and even centuries.

Running a climate model takes a lot of time even on the fastest and best super-computers, which are very expensive, and there are therefore only a handful of research institutions around the world sufficiently funded and staffed to perform those calculations. Each group of researchers models the atmosphere a little dif- ferently, or characterizes the atmospheric physics in a somewhat different manner, and hence the results are somewhat different too, especially when they deal with regional detail - and regional means anything under a thousand miles.

Nonetheless, no matter which model result we consider - after it has been run to simulate about 30 years worth of a doubled CO2

climate - one basic result is the same from all models: It will get warmer.

Let us now consider what we can expect, according to those model calculations, if we double the atmospheric CO2 content - or increase the concentration of all trace-gases to such an extent that it will be the equivalent of a CO2 doubling.

We will do this by looking at the modeling results of the three largest US institutions involved in climate modeling, namely the Geophysical Fluid Dynamics Laboratory (GFDL), NASA's God- dard Institute of Space Sudies (GISS) and the National Center of Atmospheric Research (NCAR), which all run state of the art, so- phisticated GCMs, whose results are the very heart and soul of the


current climate debate and which are similar to those arrived at by other modeling groups around the world.

At this point we will not go into any detail of the modeling and computational procedures applied in those GCMs, because they are very complex and are somewhat beside the point here for most purposes. There are a few items, however, which are of sufficient importance and to which we will return later on.

We are now going to present the image of a future climate at twice today's atmospheric CO2 level, and do this by giving a consensus view from the models, first on a global basis, and then in a little more regional detail as far as this is warranted by the hori- zontal resolution of the models.

In a 2-times-CO2 climate, the best available model calculations expect: 1. Global temperatures will be 6-8° F higher than before we emit-

ted trace-gases into the atmosphere. 2. At higher latitudes, this temperature increase would be 2-3

times as large as the global average, and in low latitudes, it would be less than the global average.

3. The temperature increase would be larger in winter than in summer.

4. Precipitation is expected to increase by about 10 percent on a global average, but is expected to increase more in mid- and high latitudes, remain the same in the subtropics and increase some in the tropics.

5. Furthermore, because of thermal expansion of the oceans, the sea level is expected to rise by 1-3 feet. Those general results are shown in Fig. 10 and Fig. 11. The In-

tergovernmental Panel on Climate Change (IPCC), the body in- stituted to probe into the greenhouse effect, arrived at conclusions which are broadly comparable. Some of their results and assumptions are shown in Fig. 12. According to them, the equivalent CO2 doubling may occur by the year 2030. Temperatures may have increased by 3-6° F by then. Additional warming is expected in the following decades until "equilibrium warming" is reached.

The "eqilibrium warming" is the temperature increase calculated by climate models after all feedback mechanisms have acted and after all delaying processes have ended.

One major example for such a feedback mechanism is the water- vapor feedback loop. It works like this: an initial increase of greenhouse forcing due to a trace-gas increase evaporates water vapor

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from the oceans. However, water vapor itself is also a greenhouse gas, and therefore the additional water vapor in the atmosphere causes more water vapor to evaporate (because if ocean temperatures rise, evaporation rises) and so on until a new equilibrium of the energy fluxes is established. This feedback alone is important enough to account for roughly two thirds of the additional greenhouse effect. In other words, without this feedback, temperatures according to model predictions would only increase by one third of the value after feedbacks. This will be important to remember, because it means that the full effect will only become apparent after the oceans have warmed up and have provided the atmosphere with additional water vapor. Therefore, ocean temperatures and atmospheric water vapor content should provide valuable monitors of greenhouse induced climate changes.

The envisioned temperature increases would indeed be very large, were they to occur, and put earth into a climate it has not seen in over 100,000 years, eclipsing by a large margin temperature variations of the last few thousand years, which in all likelihood have only been between ± 4° F.

Before we get into some of the possible drastic consequences this might have on nature and human activities in general, we will first consider the impact of such a climatic change on the U.S.

We do this by looking at the expected changes in temperature and precipitation at eight major US cities, each representing a different climatological region. Those data are shown separately for summer and winter in Table 8.

The values given here have been interpolated from published results of the three major GCMs described above. To give you an idea of the degree of variation from model to model on a regional scale, both an average of all three models and the results from the individual model are given.

The variability among models is too large at present to put much confidence in any individual forecast for a given location. Therefore, we will consider the consensus or average forecast of the three main U.S. GCMs for the eight cities chosen.

Surprisingly, the average warming at all cities is nearly the same in winter as in summer, namely 6.8 and 7.0° F respectively. Even the geographical variations are comparatively small with a somewhat larger warming expected north within the continental interior, in Minneapolis and Chicago. It may be noted in passing that those temperature increases would be considered significant within the framework of the models, since the average error of the


modeled and currently observed climate is in the neighborhood of 5° F. Therefore, the modeled temperature increases for a CO2

doubling are much larger than the expected error margin. Accord- ing to those model calculations, Chicago would enter into a climate - as far as temperature is concerned - which is presently observed in central Tennessee. This may be a welcome change for Chicagoans, who occasionally suffer from atrocious winter weather, but the summer swelter, now confined to the Deep South may extend all the way up to Chicago. New Orleans may then be in for even worse news as winters get milder, but the entire summer half year would get incredibly hot and sultry, turning New Orleans' climate into today's Miami.

In those two examples, we only considered temperature changes and no precipitation changes. But of course, it is of utmost importance in the climatic change debate not only to consider one parameter such as temperature, but other important parameters as well, the main one being precipitation. No analysis of climate change can be complete without considering precipitation. For instance, it would be foolish to state outright: "The climate of Chi- cago will be that of Nashville, Tennessee" by only considering temperature. If precipitation decreased drastically under a warming scenario, Chicago's climate would not be like Nashville's but rather like the one of Dallas or Amarillo, Texas.

Let us therefore consider the modeled precipitation changes. As we did before, we will look at an average of three GCM forecasts for the eight cities in Table 8, and we first do this for the summer months of June, July, and August. Those months are in the middle of the growing season, a time particularly susceptible to precipitation changes.

We notice at the very beginning that there is a remarkable scatter from model to model in the predicted precipitation changes. In Chicago, for instance, one model predicts a decrease of almost 8/10 of an inch per month, while the remaining two forecast an increase of 4/10 of an inch per month.

The consensus forecast for all stations calls for a decrease of monthly precipitation by less than 1/10 of an inch. The average monthly precipitation of the stations used here is approximately 3-4 inches. Therefore, the forecast precipitation change is only a very small fraction of today's observed precipitation.

If we furthermore consider the margins of error of the modeled present-day-precipitation, we realize that they are many times higher than the modeled precipitation changes resulting from a

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Figure 10. Climate model projections for a CO2 doubling. Shown is the geographic distribution of temperature changes computed by three leading climate modeling groups (GFDL, GISS, and NCAR, see text for further details). (in °C;1°C = 1.8° F).

Source: U.S. Department of Energy, Report DOE/ER-0237.


doubling of CO2. From this we can only conclude that, on the basis of current

model forecasts for the locations considered here, there will be no significant precipitation changes during the summer months. Looking at winter precipitation, the situation is somewhat diffe-

62 GLOBAL WARMING

rent, insofar as there is a slight to moderate increase in modeled precipitation, particularly at those locations where there was a decrease in summer. In general, precipitation seems to increase over the northern half of the country (see Table 8). The increase in winter precipitation appears to be larger than the occasional decrease in summer. Since winter precipitation is decisive for water management (most aquifers get recharged in winter) it is hard to construe a worsening water supply situation on the basis of current model forecasts; the available evidence rather points to an improvement in most areas. This appears to be the case even in those areas which already are under water stress today, namely the desert southwest (see Table 8).

If You Stuck Your Head Out The Window, Would You Not Feel it or Sense It?

Since we are now in the middle of "what if " wonderland, i.e., what happens if climate model forecasts are right, we will now consider - in passing - how humans beings might perceive such a drastic temperature increase.

The field in meteorology concerned with the impact of weather and climate on man and his health is called biometeorology. In biometeorology, several indexes have been developed which attempt, one way or another, to measure "climatic stress" on humans beings. Usually this is done by selecting a base temperature at which most people appear to be comfortable (there may be some argument as to what such a temperature might be) and then, for a given location, adding up the departures from that temperature in terms of either hourly, daily or monthly values. One example for this procedure is the heating/cooling degree-day- index. Here, a base temperature of 65° F is chosen and the sums of the fluctuations of daily average temperatures above 65° are cooling degree days and those below 65° are heating degree days.

In addition, human beings usually do not respond to temperature stress in a linear fashion, but rather feel disproportionally stressed the more the actual temperature moves away from the temperature they feel most comfortable at. This phenomenon is often accounted for by letting temperature-stress increase with the square of the temperature difference to the "comfortable temperature."


Table 8: Climate model predictions for eight American cities in case of an atmospheric CO2-doubling

Projected temperature changes (in ° C) (1° C = 1.8° F)

W inter Sum mer

GPDL GISS NCAR Mean GFDL GISS NCAR Mean

Minneapolis 7.0 5.0 2.0 4.7 8.0 3.0 2.5 4.5

Chicago 6.0 5.0 2.0 4.3 7.0 3.0 2.0 4.0 Denver 5.0 5.0 2.0 4.0 7.0 3.5 2.5 4.3 New York 6.0 4.0 3.0 4.3 6.0 3.0 2.0 3.7 Los Angeles 4.0 4.5 2.0 3.5 4.0 4.0 2.5 3.5 Phoenix 4.0 5.0 2.0 3.7 5.0 4.0 2.5 3.8 New Orleans 4.0 4.0 2.5 3.5 4.0 3.5 2.5 3.3 Miami 4.0 3.5 2.5 3.3 4.0 3.0 2.5 3.2

Projected precipitation changes (in mm/day) (1 mm = .04 in)

W inter Summer GPDL GISS NCAR Mean GFDL GISS NCAR Mean

Minneapolis 0.5 0.4 0.7 0.5 -1.0 0.2 -0.1 -0.3

Chicago 0.4 0.3 1.0 0.6 -0.7 0.4 0.4 0.03 Denver 0.2 0.3 1.0 0.5 -1.0 -0.1 -0.1 -0.4 New York 0.4 0.3 1.1 0.6 -0.5 0.0 0.2 -0.1 Los Angeles 0.1 0.2 0.0 0.1 0.2 0.2 0.1 0.16 Phoenix 0.1 0.3 0.5 0.3 0.0 0.3 0.0 0.1 New Orleans -0.1 -0.2 0.0 -0.1 -0.2 0.4 0.0 0.06 Miami -0.2 -0.2 -1.0 -0.5 -0.4 0.3 0.0 -0.03

Source. After data from U.S Department of Energy, Report DOE/ER-0237.

Example:

Let us assume you feel comfortable at 70° F. Then at 50°, 20° lower, you would get somewhat uncomfortable, but at 30°, another 20° lower, you would not simply be twice as uncomfortable, but four times as uncomfortable and freeze tremendously if you were unprotected, not to mention what would happen at 10° F, wind-chill factor excluded.

One such example of a comfort-index is presented in Fig 13. It

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Figure 11. Climate model projections for a CO2 doubling. Shown is the geographic distribution of precipitation changes computed by three leading climate modeling groups. (GFDL, GISS and NCAR, see text for further details). (in mm per day; 1mm = .04in).

Source: U.S. Department of Energy, Report DOE/ER-0237.


shows, in relative units, the level of comfort you - or an average person - would experience under the presently observed climate at any given location on the map.

The scaling is such that the higher the numerical value, the more comfortable you feel.

If we now take up the examples we used before, and let Chicago

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Figure 12. Simulation of global warming between 1850 and 1990 thought to have resulted from the observed trace gas increase and projection to the year 2100 using the IPCC "BaU" trace gas scenario. Source: IPCC, 1990.

have the climate of Nashville, that would result in an overall increase in comfort almost entirely due to the milder winters.

If, on the other hand, we let New Orleans have the climate of Miami, we would decrease the comfort there almost entirely due to the hotter, unbearable summers.

We realize, then, that climate change, if it progresses the way the models predict, is a mixed bag indeed, since it appears that people in the southern states will on average suffer under this change, whereas people in the northern states will actually feel more comfortable in the warmer climate of the future.

It may be noted that no allowance for humidity has yet been made here. If this is done, as it should be, the pattern is liable to change somewhat.

Similar exercises could be carried out on the impact of higher temperatures on a number of human activities, but we will not further pursue that here, since we are still in "what if" land and it would be counterproductive to spend a lot of time and effort as- sessing the impact of a change we do not even know is coming or not.

Is It Only On TV Or Do The Models Show It?

Let us instead direct our attention to four specific items related


to the climate change issue which frequently come up in public debate, and which are most commonly cited when it comes to de- scribing the negative impacts of global warming:

1. The shifting of climatic zones 2. The melting of polar ice caps 3. Rising sea levels and inundation of coastal low lands 4. Increasing frequency and severity of droughts in the Ameri-

can corn belt At this point we will only be concerned with the question of

whether or not these impacts can be deduced from current best available model predictions, but we will not be concerned (yet) with the question of whether we can already see any such effects or really have to expect them. What we are trying to do, then, at this point is determine whether there is any basis in model predictions for the horror stories one hears so much about in the media, or if some of the model results got lost or altered in the process of transmission from scientific community to the media.

1. The shifting of climatic zones

Life on earth is adapted to the way climatic zones are arranged. The position of those climatic zones is determined by the large scale atmospheric circulation: The tropical zones along and within some distance of the equator with their frequent and abundant rainfall, the trade wind region, the subtropical high pressure belt with hyperarid regions, such as the Sahara desert, at a distance of roughly 30° latitude, followed, towards the poles, by the prevailing westerlies, in which most of the U.S. is located, and in which low pressure systems track eastward, guided by the polar jet stream at about 50°.

The position of the main features of the general circulation is determined first of all by earth's rate of rotation; second, by the temperature contrast between equator and pole; and third, by the distribution of land and sea on earth.

Notably the location of the subtropical jet stream, which go- verns the position of the subtropical high pressure belts and therefore the arid zones, but also the location of the polar jet, which is much more variable, and determines which way the rain bearing storm systems move, depend on the temperature gradient between the equator and pole in the following manner: If the gradient (or contrast) decreases, the jet streams move toward the poles; if it increases, the jet streams move towards the equator.

Figure 13. Geographical distribution of a climate stress index over the U.S. The index is defined such that high values indicate low stress whereas low values indicate high stress. Low values over the northern U.S. are a result of cold winter weather and low values over the southern U.S. are caused by hot summer weather. Source: R.E. Munn, Biometeorological Methods, 1970.

Therefore, a changing position of the jet stream as a result of a change of the equator-to-pole temperature gradient would result in an alteration of the circulation regime, either turning a dry region into a wet one or vice versa. It may again be noted that it is not so much the impact of the changing temperature itself which has an adverse effect, but rather the changing pattern of water availability, since so much of our life depends on water.

As we saw before, and according to model predictions, in a climate warmed up by trace-gases, surface regions near the poles would warm up much more than regions near the equator, thereby reducing the temperature gradient between equator and pole - which would then result in a poleward shift of the jet streams by a few degrees latitude. Hence, regions at the poleward boundary of the subtropical dry areas would experience less frequent incur- sions of the polar jet stream with its rain-yielding storm systems. The climate zones would shift - with particularly detrimental effects at the equatorward margins of the westerlies, which would then turn into arid zones.

So far so good. Turning again to the models, there is one small item someone must have overlooked: It is not the temperature gradient of the surface layers which is important for the position

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of climatic zones, but the temperature gradient of the entire troposphere. And here the models almost unanimously come up with a very surprising result: Even though there is a large warming of the surface layers of high latitudes, and small warming at low latitudes, there is large warming in the upper troposphere at low latitudes and only small warming at high latitudes. As a result, the warming averaged through the entire troposphere is fairly uniform, so that the gradient does not change very much, even though there is warming everywhere.

Consequently, none of the models expects a shift in the position of the major jet streams and of the way the climatic zones are de- lineated by the circulation regimes. The warming itself does not constitute a shift in a climatic zone the way it is often portrayed by the media. This misconception probably arises from the simple notion that if it gets warmer at any given point, the climate there will be replaced by a climate that is normally observed some distance closer to the equator. But to repeat this point, the climatic zones are defined not only by temperature, but also, and in some cases more importantly so, by precipitation or water availability in general, which is tied not so much to temperature alone but to the position of a geographic area within the general circulation of the atmosphere.

To elucidate this point, think of two places in the US which are roughly at the same latitude and which have approximately the same average annual temperature, namely Los Angeles, Califor- nia and Savannah, Georgia. As anyone knows, "It never rains in Southern California", whereas there are lots of "Rainy nights in Georgia". In bare numbers, L.A. receives about 15 inches of precipitation and Savannah close to 50 inches, resulting in rather sparse vegetation in Southern California and a lush biosphere rich in species abundance in Georgia. The obvious difference in climate, despite similar temperatures, is entirely due to the different position of the two cities within the general circulation.

2. The melting of polar ice caps

Almost nothing in the global warming debate heats up the public like "the melting of the polar ice caps" and the ensuing negative impacts of rising sea levels, inundation of coastal low-lands and so on.

It sounds so horrific and truly threatening, and it is still one of the biggest misconceptions about the impact of the greenhouse effect. Why? Well, here it goes:

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Let us first differentiate between the two polar ice caps on earth, i.e., the one in the Arctic and the one in the Antarctic.

The arctic "ice-cap" is an ocean which is frozen over and which is surrounded by the land masses of the North American and Eu- rasian continents. The northpolar ice-cap is sea ice which is floating on the ocean.

The GCM model results, in a 2-times-CO2 scenario, expect this sea ice to melt somewhat and to retreat polewards by about 200 miles, but never to melt substantially or even completely.

What would the implications of that melting be then for the sea level? Exactly none.

This is simply because, as the floating ice melts, it only takes back the sea water volume it displaced when it was floating on the water as ice. You don't believe it?

Pour yourself two fingers of sour mash, on the rocks, fill it up with soda until the ice cubes completely float, (For the ladies: It works on Daiquiries too) and then, even though it breaks your heart, don't drink it, but let it sit until the ice has completely melted, and watch the waterline in the glass over time.

You will notice that even though you had a substantial amount of ice in your highball glass, the water level after the ice has melted remains the same.

Now you may enjoy your drink, if you can stand it stale. In principle, the same thing would happen to the floating sea ice

and sea levels in a global warming scenario. The situation would be somewhat different, however, in the

Southern Hemisphere, because there the ice cap sits on a continent which is surrounded by the oceans. The waters surrounding Ant- arctica also freeze over and, as in the Northern Hemisphere, the models expect some melting of that sea ice as well, pushing the ice line back towards Antarctica. In terms of sea level rise, we know by now what is (not) going to happen.

You may ask, why is there no more melting? Simply because the warming envisioned by the models to result from a CO2 doubling is not large enough to melt more.

Let us assume the wintertime greenhouse warming over an area of Arctic and Antarctic ice is 20°F. During the winter, the actual temperature over most iced-up areas is substantially below 0° F. In other words, even if the temperature rose by as much as 20° F, we would still be very much below the melting point of 32° F.

Furthermore, the large warming expected by most models in high latitudes must not be viewed as the cause of the ice melt but


rather as the result of it - for the following reason. As we saw before, all GCMs compute their climate parameters on a net of grid points, which are spaced, depending on the model, 500 to 1000 km (300 to 600 mi) apart. We also saw that a sea-ice melt is expected to extend about 200 miles toward the poles. Over these areas, which would then be ice-free - 200 miles - temperatures would be in the mid-30s, typical values for the open arctic ocean, whereas before, over the ice, they were sustantially below 0° F. It thus follows that the warming which occurs in the narrow de-iced strip is possibly of the order of 40° F. This very large warming now is, by the averaging procedures applied in the models, drawn out to the neighboring grid points, spaced 300 to 600 miles or 5°-10° latitude apart, giving the impression that a large area between latitudes 60° and 80° is warming up — not by 40° F but possibly by a still substantial 20° F.

Therefore, because of the internal workings of the GCMs, a warming is predicted which would never exist in reality, even if the general warming projected by the models were to occur.

The actual retreat of the sea-ice would result from the more moderate warming of high latitude oceans, which might be in the neighborhood of 5° F.

However, there is still more to come in the land of counter-in- tuitive phenomena.

We mentioned earlier that the Antarctic is a block of ice sitting on a continent. In fact, more than 90 percent of all the ice anywhere on earth is located there. (Greenland accounts for only 5 percent, the rest is in various glaciers around the world.)

Given the alarm over global warming, which is supposed to be particularly large at high latitudes, scientists have tried to estimate what would happen to the antarctic ice shield in a 2-times- CO2 scenario.

As we have just seen, there would be no significant melting of that shield itself, but only some melting of the sea-ice surrounding Antarctica. If the Antarctic ice shield itself melted completely, which could only happen under much higher temperatures than expected from a CO2 doubling, and which would take thousands of years because of the slowness of response of that large an ice mass to changed conditions, sea levels would rise by 150', a figure sometimes seen in the media. But clearly, this is not one of the concerns of the current debate and may only underscore the fact that things sometimes appear about the greenhouse effect in the media which have a questionable scientific basis at best.

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Back to the antarctic ice shield. Scientists analyzing its response to a temperature increase which GCMs expect from a CO2 doubling found out - perhaps to the disgruntlement of many doomsday preachers - that it would grow and not melt.

Now, why is that? First, as we have seen, since Antarctica is quite cold, even a sub-

stantial warming would not result in any significant ice melt. But second, and more important, since the air over and around

Antarctica is supposed to warm up so much, it can hold much more water vapor than it can now. The capability of air to hold water vapor roughly doubles with each temperature increase of 20° F (see Fig. 2). Some of that water vapor would be converted to precipitation and fall out - at the prevailing temperatures in the Antarctic - as snow. That snow would simply stay there and accumulate - eventually thickening the ice pack.

Yet this is in essence a net transfer of water from the oceans to the Antarctic, where it may remain for thousands of years - taken away from the oceans - and actually lowering the sea level by about a foot.

Although this seems completely surprising to many people, cli- matologists have known about it for quite some time. In fact, there is some research which indicates that, over geologic times, there were periods when the sea level was much lower during warm than during colder episodes. This obviously runs counter to the expected sea level rise thought to result from global warming. You might then ask, since the polar ice caps are not going to melt, and in fact may even grow (not in extent but in thickness), why is the sea level expected to rise?

There are two reasons. One, sea water expands as it warms, as all things do. Most of the expected rise in sea level is related to the envisioned warming of the oceans.

Two, because of the expected general warming in the interior of the continents, some melting of glaciers is thought to occur which would also add to the sea level rise. How much rise from melting of inland glaciers is highly debatable, but definitely less than the rise from ocean warming. But this is minimal with respect to the rise expected due to ocean warming.

3. Rising sea levels and inundation of coastal low lands

One of the most serious impacts of a global warming must be seen - if correct - in the rising sea level.


In the preceding paragraph we have already seen that outland- ish claims of a sea level rise of the order of 150' are not supported by modeling results of any possible climate change which might occur from rising trace-gas levels in the next 100-300 years. Such a rise would require a melting of the whole antarctic ice sheet, which no one expects to happen even from a severalfold increase of CO2. Even a melting of the so-called West Antarctic ice shield, which rests on a sloping rock plateau below sea-level is not expected from any warming of the magnitude envisioned for the next few centuries.

If it melted, sea levels may rise by about 15'. What is expected then is a rise of 1 to 3', mainly as a result of

thermal expansion of the ocean waters and some glacial melt in the continental interiors.

But even a rise of only 3' would pose almost insurmountable problems to many nations, including the US. It has been estimated that the damage of this seemingly small rise to a city such as San Francisco alone would be in the billions of dollars.

The picture becomes even gloomier if we consider countries like Bangla Desh, which might be flooded to a considerable extent, without having the technological and financial clout to do anything about it.

At this point we will not go too much deeper into the gloomy details; suffice it to say that if the model predictions of 6-8° F temperature rise were correct, there is a possibility of an ensuing sea level rise of the order of 1-3' resulting from thermal expansion of ocean waters and glacial melt in continental interiors.

Recently, scientists seem to have more closely considered the real impact of higher temperatures on polar ice shields, and have consequently lowered their estimates on greenhouse related sea level rise to about a foot or so for a CO2-doubling. Indeed, observations indicate that ice shields in Greenland and the Antarctic have been growing in recent years. Newer model calculations have lowered estimates of future sea level rise even more. Accord- ing to the calculations presented in Fig. 31, the sea level would only rise by an insignificant 1-2" over the next 50 years. Less gloom by the day.

4. Increasing frequency and severity of droughts in the American corn belt

The American corn belt is not only the bread basket of America,

74 GLOBAL WARMING

but also of a substantial portion of the entire world. If some adverse climate changes were to occur there, the ramifications would not be confined to the farming district, but would have re- percussions on the economy and prosperity of the entire nation as well. For that reason, a thorough examination of possible future changes appears to be fully justified.

For present purposes let us define a drought as an extended period of hot weather combined with a lack of precipitation. Since hot weather occurs mostly in the summer half of the year, which is also the growing season, when an adequate supply of water is quintessential and substantial negative impacts on plant growth might result from either a reduction of precipitation or an increase in evaporation, or a combination of both, we can limit the present discussion to the summer months.

A little earlier, we examined model-predicted temperature and precipitation for a few selected American cities in summer. We concluded that temperatures increase by about 7° F in cities close to the corn belt (Chicago), while precipitation would not change significantly.

However, an increase in temperature will then in general lead, other things being equal, to additional evaporation and therefore additional drying of the surface soil. Therefore, if the model predictions are correct, we can indeed expect, if not an increasing frequency of droughts, an increasing severity of droughts. The impact of additional drying would be particularly detrimental in those areas which receive marginal precipitation to begin with, namely the Southwest and also the western parts of Oklahoma, Kansas and Nebraska.

There are two silver linings in this generally gloomy cloud, however, which is fortunately still a "what if" scenario. For one thing, because of increasing precipitation in the winter half of the year which the models expect in their two-times-CO2 version of tomorrow's corn belt, there might be some way to store the water and use it during the summer (in an irrigation system such as that proposed by NAWAPA - North American Water And Power As- sociation) and second, land in more northern regions, which has not been suitable for agricultural use up to now because of cold temperatures, might become suitable in a warmer world.

Furthermore, some of the adverse effects of high temperatures on agriculture could be avoided by planting earlier in the season, which would still be moist and cool enough. The length of the growing season is expected to increase in a warming climate. But


before we indulge too much in the doom and gloom, let us remember that we are still only considering model forecasts — which may be far removed from any reality. Our next task will accordingly be to determine to what extent we can trust those forecasts.

4.

The Acid Test: Models Vs. Reality

ell, now it's finally curtain time! Now we can finally find out whether we have been in the land of make-believe or in the land of reality, whether our method was

science or science-fiction, whether we should really head for high ground, move north, sell land in the corn belt, or whether it all was a figment of our imagination, a gigantic ooops!, in other words, the real rest of the story. Back to the bare facts. We have just been on a journey through computer wonderland. We have taken a look into the future and tried to get an idea of what our climatic future might be like if trace-gases built up as rapidly as some people believe, and if the climate really changed the way our best available computer models see it changing.

We already had to modify the first if — i.e., we could see some promising signs that the trace-gas build-up might not progress as rapidly as some people fear.

Furthermore, our look at the computer-generated future climate was a mixed bag at worst, and certainly no doomsday tale in the balance. Contrary to many public declarations that there would only be losers in a trace-gas induced climate change — although politically quite understandable - it is quite obvious that areas in the mid- and higher latitudes only stand to gain from a climate change as projected by the models; this is particularly true when the beneficial effects of an increased CO2 level on the biosphere are factored in.

However, there can be no doubt that the possible adverse impacts in other areas of the world warrant serious consideration of remedial and/or preventive measures against such a change — if it will really occur.

The scope of the envisioned changes, but also the scope of the remedial measures are horrendous. It would in fact change the basic frameworks of our societies either if those climate changes really occurred, or some of the proposed measures had to be adopted. It is absolutely necessary at this point to critically examine those model forecasts before a decision can be made on any course

W


of action to counter a possible threat to the climate. The usual way to check a forecast is to wait and then compare

predictions with observations. Obviously, we cannot do that, because no one wants to wait

until the year 2030 or later to see whether climate model predictions are correct - when any possible damage might have already been done.

Another way would be to wait for maybe 10 or 20 years, and then see if temperatures have really risen to an extent compatible with model predictions, but still small enough not to have caused any of the expected damage. This is an approach which might not seem the worst of all strategies if we consider, as we will a little later on, that those eras in the history of climate which were warmer than today by about 2 to 4° F were called "climate optima" - and for good reasons as we will see. This approach simply assumes that we can afford to wait, because the worst that can happen in coming decades is a slight warming moving us into another climate optimum but giving us more time to devise the best countervailing measures.

But we can do better than that. We know that trace-gases have already risen for more than 100 years: CO2 has gone up from about 280 ppm to 350, roughly 25 percent, other trace-gases, mainly methane and, after WW II, the CFCs have risen much more (see preceding sections) in percentage terms, so that we now have about 50 percent of the additional man made greenhouse effect from all trace-gases combined (or radiative forcing) thought to occur from a doubling of CO2 alone. It may be noted at this point that the greenhouse effect does not increase linearly with trace-gas concentrations, but at a progressively lesser rate. That means that the emission of a fixed amount of a trace-gas between, say, 1950 and 1980 enhances the greenhouse effect much more than the emission of that same amount between 1980 and 2010, because the earlier emission has - to some extent - saturated the absorptive regions in the spectrum (see also Chapter 1).

The obvious question then is: If the models are right, should it not be possible to already see a warming due to the trace-gas build-up which has already occurred?

Simple question, simple answer: Yes! Then let us examine how much global temperatures should have risen if the model predictions were correct.

To do this, models could be run not only in a 2-times-CO2 mode, but in a 1.25 times CO2 mode, or in a slightly higher mode, to ac-

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Figure 14. Simulation of global mean temperature rise between 1850 and 1990 thought to have resulted from the observed trace gas increase. After IPCC, 1990.

count for the additional trace-gases which have built up in our atmosphere - or they could also be run in a mode where trace gases are continuously added to the atmosphere - thereby simulating real life events. Those models are called "transient response" models.

After carrying out those calculations, the result is that there should have been an "equilibrium warming" of more than 2° F. We remember that the equilibrium warming is the warming reached after the greenhouse effect has worked its way through all compartments of the - modeled - climate system and after all feedback mechanisms have acted.

Enter the oceans one more time. As we saw before, the oceans have a very important function as a sink for atmospheric carbon dioxide and may act as a retardant large enough to delay a doubling of CO2 into the 22nd or even 23rd century. But not only do they act as a sink for carbon dioxide - they are also a sink for heat.

Some of the heat generated in the atmosphere by the green-


house effect is transferred into the oceans and stored there. As a matter of fact, the complete and final atmospheric warming will only be achieved after heat transfer equilibrium between oceans and atmosphere has been reached.

And this may take a lot of time, as we have seen with CO2. Moreover, it is very tricky business to model.

The current state of the art of modeling would predict that, due to the oceanic slow-down of atmospheric warming, we should now (in the early 1990s) see a warming of close to 2° F due to the build-up of all trace-gases. This assumes that the climate would warm by 6.5° F in the case oi a CO2 doubling. Fig. 14 shows the manner in which trace-gas related warming should have progressed since the latter half of last century. The warming of nearly 2° F will be the yard stick against which to compare the observed temperature trend in the real atmosphere.

To do this, we will first have to settle the issue of what temperature the modeled temperature rise has to be pegged against.

Everyone would agree that it should be the average, long-term state of the atmosphere, unperturbed by the anthropogenic influ- ences we are trying to see.

Going back to the section where we defined climate, we realize that it has to be at least a 30 year period; to eliminate "climatic fluctuations", which are characterized by variations in temperature from one 30 year period to another, an average over several 30 year periods would be better yet.

This might then characterize an unperturbed, long-term climatic state against which we wish to assess the impact of a trace-gas related warming.

Since trace-gases are not the only factor which has a bearing on climate, we may face very long-term natural climate variations acting on the same time scale as the ones presumed to occur from a trace-gas build-up, and which may act to confuse a trace-gas related temperature trend with one due to natural causes. We post- pone that aspect for the time being and only wish to ensure at this point that trace-gas related temperature changes are not confused with short-term temperature fluctuations due to different causes.

A reasonably reliable temperature trend for the earth as a whole has only been compiled for about the last 140 years. Moreover, we can not even speak of a truly global trend, because most temperature measurements were only taken over land, and so most of the global Northern Hemisphere and Southern Hemisphere trends talked about in public, and the ones we will be concerned with,

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are in fact "land-based" temperatures. Let us pause for a moment and consider the implications of that. You may ask: What significance does a land-based temperature trend have if nearly 3/4 of the earth's surface is covered by oceans? And are we not comparing apples to oranges when we compare an observed land-based temperature trend with a modelled temperature trend which includes the oceans? Might it not be that we see a trend over land, which is nullified or at least tempered by a countervailing trend over the oceans?

Quite right, and we will therefore return to those questions in a moment.

The Three Claims

The greenhouse/global warming debate would not have grown to such proportions had it not been for the fact that temperatures did indeed increase over the past 100 years, and not only that, six of the warmest years occurred within the last decade, namely 1990,1988,1987,1983,1989, and 1981 in that order.

Some scientists have gone so far as to claim that this is the final proof that the greenhouse effect is indeed with us, and furthermore that the warming we have seen over the last 100 years, which, according to the land-based records, is 1.3° F, is right where it should be according to the models. As a result, they say, we had better be prepared for the full treatment of the model-predicted 6- 7° F temperature rise for a doubling of CO2 and act immediately to stave it off.

Those claims are at the very heart of the current debate. The entire international greenhouse conference circus, hasty statements by politicians, and reports by every imaginable organization, panel, study group and so on, revolves around them, and we will therefore examine them in full detail.

Of Dips And Spikes

Let us start out by considering the land-based temperature trend of the Northern Hemisphere, the Southern Hemisphere and the earth as a whole for the last 140 years.

Those temperature trends are shown in Figs. 15 and 16. They have been compiled by a climatic research group in the UK. Their work is generally perceived to be the most reliable, which is why it is shown and used here.

Figure 15. Observed temperature trends in the Northern Hemisphere since 1850: a) over the continents, b) over the oceans, c) of sea surface temperatures. The smoothed curve shows 10-year averages Source: Jones et al., Journ. Clim. Appl. Met., 1986a.

The temperature curve in this diagram is a so-called filtered curve, designed to suppress the short-term variations we are not interested in. It shows temperature departures from a base period. If we now look at where this line was in 1880, we find it at -0.9 °F and if we look again at 1980, we find it at 0.4°. The difference is 1.3° F - Bingo! Just what the models ordered, and there is your "proof".

But let us now recall how we have defined climate. For the purpose of detecting a trace-gas related warming, we have to compare the current climatic average to an earlier, unperturbed, long-


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term climatic average, because without that comparison we run into the danger of relating shorter term fluctuations, which may occur on time scales of 10 to 30 years, to a presumed trace-gas related warming.

Hence, we should compare the current, 30 year average to an earlier, unperturbed one.

We now have to determine a span of time in which the climate may be considered to be unpertubed, even if we assume that the modeled temperature increases did in fact take place.

For most practical purposes, we may assume that climate remained undisturbed as long as the modeled temperature increase due to trace-gases remained below about 0.2° F, because 0.2° would be below the limit of detectability and well within the range of natural variability.

We can now look that time up in Fig. 14, and we find it to be about 1900.

Figure 16. Observed temperature trends in the Southern Hemisphere since 1850: a) over the continents, b) over the oceans, c) of sea surface temperatures. The smoothed curve shows 10-year averages. Source: Jones et al., Joum. Clim. Appl. Met., 1986b.


If we now - in this Fig. - take an average of the temperature between 1850 and 1900, a climatically relevant time scale suitable for our purposes, we find the temperature to be not -0.9° anymore, but -0.5° F.

If we apply the same kind of averaging procedure to the period between 1960 to 1985, for example, we arrive at 0.2°.

If we did the same for the Southern Hemisphere temperature trend (Fig. 16), the result would be approximately the same - within the limits of measurability and detectability.

Therefore, if we attempt to estimate the true, i.e., climatically relevant, temperature change over the land masses of both the Northern Hemisphere and the Southern Hemisphere between the latter half of the 19th century and the latter half of this century, we arrive at 0.7° F as opposed to 1.3°. The larger figure of 1.3° is then due to the impermissable gauging from a temporary dip in the temperature curve to a temporary spike.

But those dips and spikes have nothing to do with what is called "climate", let alone climatic change, which is what we are interested in.

You may notice that we have determined the actual, climatically relevant temperature increase over the continents to be only about one half of what it should have been - according to best available model calculations (see Fig. 14) - on the average from 1860 to 1985.

However, we are not really concerned with the temperature trend over the land masses alone, since a "global" trend obviously cannot ignore 70 percent of the earth's surface, and must encom- pass the trend over the oceans as well.

Therefore, if we really want to compare observed "global" trends to the model-calculated "global" trends, it is also necessary to consider the temperature trends over the oceans, because all model-predicted temperature changes include the oceans as well. The problem here is that data coverage is much worse than for land areas, and the problem becomes really dramatic the further back in time we go - especially in the Southern Hemisphere.

Scientists have attempted nonetheless to reconstruct a temperature trend over the oceans back to about the middle of last century. Needless to say, extreme caution should be exercised when interpreting the early portion of the data. This is particularly the case in the Southern Hemisphere, where an oceanic temperature trend for the areas between 45° and 65° S can not essentially be determined for the second half of last century.

84 GLOBAL WARMING

Consequently, any temperature trend for the Southern Hemi- sphere oceans should be viewed with a considerable amount of caution. Temperature trends over the oceans can be determined in two different ways: First, by directly measuring the sea surface temperature (SST) (to which we would have no objection, since according to the models, the SST's are supposed to warm up by an amount comparable to the warming of the lower atmosphere directly above them), and secondly, by measuring air temperature directly above the water. To reduce unwanted interferences from direct solar radiation and heat trapped onboard the observing platforms, usually ships, of course, which are much worse in the daytime, night time temperature records (NTMAT) are used in long-term temperature analyses over the oceans.

Both sets of records are shown separately for the Northern He- misphere and the Southern Hemisphere in Figs. 15 and 16. You will notice that in both hemispheres, the SSTs and the NTMATs, which are also filtered in the same way the land-based temperatures shown above them are, run very much parallel, as one would expect them to, since, in a long-term average, trends of SSTs and the air temperatures directly above the sea surface should not differ to any great extent.

If we compare the marine temperatures with the land-based ones, we notice a remarkable difference between the two before and around 1900:

While there is an almost continuous warming over land between 1880 and 1980, the marine trends show rapid cooling up to the early part of this century, and then warming from then on until about 1960, followed by cooling in the Northern Hemisphere and continued warming in the Southern Hemisphere. In other words, there are some considerable differences between hemispheres, and between land and marine trends - particularly in the early portion of the data. There is no reason to doubt the reality of those differences, although we might raise questions about their magnitudes. Let us now progress the same way we did before with land-based temperatures, and define the unpertubed temperature as the average 1850-1900; again, we take the period from 1960- 1985 as the recent, trace-gas tainted period. In the Northern He- misphere, the average for 1850-1900 would be about

-0.4° and the 1960-1985 value would be -0.2°, yielding an increase of 0.2°; the corresponding figures for the Southern Hemi- sphere would be -0.2° last century and 0.2° this century, yielding an increase of 0.4° F.


Thus, the temperatures over water and the SSTs have increased by about half the amount for temperatures over land. Other research groups have even concluded that there has been no warming at all over the oceans since the middle of last century, and instead a very slight cooling (see Fig. 17). If their estimates are correct, there has been no global warming at all if oceans and continents are considered together.

But let us stick to the former estimates, which are probably more widely accepted - rightly or wrongly we cannot decide. If we now appropriately weigh those figures according to the fraction of the earth covered by land and sea in both hemispheres, and calculate a "true global" temperature change which is climatically meaningful and takes account of the trend over land and sea, and which we can therefore compare with the modeled trend, we arrive at a value of about 0.5°-0.6° F.

Figure 17. Temperature trends over the oceans of the Northern and Southern Hemisphere since 1870 according to a study by Oort et al. (1987). Source: Oort et al., Climate Dymamics, 1987.

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Figure 18. Global temperature trend since 1850 according to IPCC (averaged over oceans and continents). Source: After IPCC, 1990.

This figure is indeed very close to the one arrived at by the IPCC. Their global temperature curve is shown in Fig. 18. It im- plies - as our figure does - that previous estimates of global warming over the last 140 years or so have to be slashed in half. We now look again at Fig. 14 to recall the modeled temperature change for the average 1860 to 1985 and we arrive at a little better than 2° F. We now realize that the modeled temperature change is larger than the observed one by a factor of nearly three.

This realization may make life harder for greenhouse activists! On the basis of what we have found out so far, we may well be justified in seriously questioning not only the correctness of the model projections, but also the demands advanced under the assumption that those projections were correct.

Let us reiterate why the contention "We see the warming the models are predicting" is untenable: 1. Climatic averages predicted by the models have been compar-

ed with non-climatic "dips" and "spikes" in the temperature curve.

2. A global warming predicted by the models has been compared with a land-based temperature trend only, whereas a "true global" trend - comprising oceans and continents - should ha- vebeen used.


3. The actual, climatically relevant warming of the atmosphere over oceans and continents has only been about one third of what the models calculate. Even if the entire observed warming over the last 140 years

were attributed to the greenhouse effect, which is highly debatable, as we will see later on, we would still have to seriously question the relevance of the model calculations, because they have us in for close to three times the observed temperature rise. The implications of that realization are immediately apparent: If a calculated temperature rise of about 2° for the trace-gas increase already observed is too large by a factor of three, the predicted temperature rise for a doubling of CO2, 6-7°, may also be too large by a factor of three, which is a fair assumption, since temperatures are expected to rise smoothly and continuously as trace-gas concentrations go up. The IPCC draws a different conclusion from this discrepancy. They think the observed temperatures are at the lower end of model predictions, and the difference could be due to natural variations. In the following we will analyze some of the factors which might be related to the temperature rise of the last century in more detail and see if there is some evidence for or against the greenhouse hypothesis.

Wrong Timing

We are not yet satisfied with our analysis of the temperature trend of the last 140 years; we want to present the temperature history from a slightly different, but possibly even more revealing angle.

Let us imagine we are travellers in time, and we embark on a journey beginning in the year 1850. As knowledgeable people, we know about the greenhouse theory and we expect the climate to warm up the way it is depicted in Fig. 14.

As we travel through time, we notice that it is generally getting warmer. Especially between 1910 and 1940, there is a whopping temperature increase - not only over the continents, but also over the oceans - and by the time we reach the 1940s, temperatures over land are almost 1.3° higher, in the filtered 10 year average, than at the outset of our journey (see Figs 15 and 16).

If we now look the other way to the greenhouse curve (Fig. 14), vve notice that temperatures should only have risen by a paltry 0.4°. Now what?

Greenhouse theory or not, at this point we can only conclude

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that the very largest part of the increase of 1.3° must have been caused by natural fluctuations in the climate system, the causes of which we do not know yet, but which we will try to analyze later on.

The temperature increase in the first part of this century, which was as large as the one predicted to occur from the trace-gas increase up into the 1980s, could therefore not have been caused by a trace-gas build-up, because that build-up did not occur until after WW II. And everyone would probably agree that we cannot explain a temperature rise before 1940 by a trace-gas increase after 1940: that would be sheer nonsense.

We now continue our journey through time and must bedaz- zledly realize that as trace-gases build up in the atmosphere and the greenhouse curve (Fig. 14) goes up as well, observed temperatures go down (Figs. 15 and 16). 'Well, why shouldn't they?', we ask, because they went up before 1940, obviously due to natural causes, why shouldn't they go down - also due to natural causes. Temperatures went down about 0.4° until the mid-1970s, whereas the greenhouse should have warmed us by about 0.9° during that time.

The first symptoms of an attenuated greenhouse theory appear. If we wanted to explain the observations in terms of the greenhouse theory, there should have been a natural cooling - without the greenhouse effect - on the order of 0.4 + 0.9° = 1.3°F.

This cooling, due to natural factors over only 30 years, would have been quite large by historical standards, particularly since, as we will see a little later, we can not identify any natural factors which might have caused it.

You will notice that it is somewhat difficult to analyze how the greenhouse effect may have acted and is now acting, since we cannot assess how the natural climatic system would behave without trace-gases being present. Clearly, greenhouse proponents could always respond to claims that the warming observed over the last decades is significantly less than predicted by making the coun- terclaim that there was a natural cooling present in the climatic system - veiling the greenhouse effect. While this is theoretically possible, it is nonetheless highly speculative reasoning, and it also seems to contradict what we know about other factors influencing the climatic system over the last 140 years: Most of those factors point to a warming and not to a cooling. Moreover, the hypothetical cooling invoked is slowly but surely becoming improbably large.


We may therefore be justified in rebuffing the contention "We see the warming the models are predicting" on the basis of the following additional points:

1. The bulk of the warming of the last 100 years occurred before it could have been caused by the greenhouse effect.

2. The greenhouse theory could only be maintained if a hypothetical, large natural cooling did occur since 1940 which vei- led the greenhouse effect.

Let us now continue our journey through time. As we enter the 1980s, the greenhouse proponents get their biggest break yet: The climate warms up rapidly, mostly over the continents, but also over the oceans of the Southern Hemisphere. The '80s, it turns out, are the warmest decade we have seen on our journey which began in the middle of last century, with 1990,1988,1987,1983,1989 and 1981 being the warmest years. Now we finally have it, the irre- futable evidence that the greenhouse has arrived. Or so they claim.

Now, after dissecting the first claim, i.e., that the warming seen between 1880 and 1980 is compatible with climatic model predictions, we will take a closer look at the second major claim, that the warmth of the 1980s must be seen, if not as the final proof of the greenhouse effect, then as a very strong piece of circumstantial evidence in its favor.

We start out by going back to our definition of climate and climate change.

Climate is defined as a long-term average. Dips and spikes in the temperature record do not constitute a climatic change. This point will be further illustrated later on when we take a look at historic and ancient temperature records dating back to the days before 1850. In general, every climatologist knows that it is not permissable to extrapolate a short-term trend from a portion of the temperature record into a long-term trend. One would have to see a number of years like 1987 and 1988 to call that warmth a long-term trend and speak of.

Warming In The Wrong Places?

Let us now take a closer look at those last 10 to 15 years which have brought us that warmth and which were, climatically speaking, quite remarkable.

If we took a close enough look at the temperature record to see individual years, we would notice that some spectacular changes must have taken place between the years 1976 and 1977, because

Figure 19. Temperature departures in the troposphere (between altitudes 0-9 km above sea level) of the Northern Hemisphere averaged between 1977-1986 as a function of latitude and separated by continents and oceans. The base period is 1951 - 1960. Source: After Weber, Int. Journ. Climat, 1990.

temperatures jumped upward by 0.6° F, reversing the downward trend of earlier decades, particularly in the Northern Hemisphere. Subsequently, temperatures stayed up and rose even further. If we now attempt to track down the sudden appearance of renewed "global" warming, it does not take long to find the culprit: The tropical Pacific.

Here we find the famous El Nino events. In an El Nino, large amounts of warm water (82-84° F), normally stored in the western Pacific, flow eastward and may even reach the west coast of South America, where they very often arrive right around Christmas time — thus the name El Nino, Spanish for the child (of God)— displacing waters which are normally cool (about 76° F). Above

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that warm water, intense flows of heat and moisture into the atmosphere set in, causing rains in the wrong places and shifts in wind patterns almost everywhere around the world. One particular phenomenon is the spread of warmth around the tropical belt; that means not only that an El Nino year is a warm year over the tropical Pacific, but also over the entire tropics. The tropics themselves, however, if counted out to latitude 30°, comprise fully half of the surface area of the world. In other words, if it gets warm in the tropics, the rest of the world may stay normal, or even colder than normal, but it may still be warmer than normal on a- "global" average. This is precisely what happened the last 10 to 15 years.

It is no surprise anymore to learn that the "unusually warm years" of 1983,1987, and 1988 were years in which the El Nino was in effect. If we now look at the temperature distribution in the Northern Hemisphere between 1976 and 1990, differentiated by tropics (0°-30°) and extratropics (30°-90°), and if we consider a composite temperature trend over land and oceans, we find that the extratropics have been below normal almost every year. This is particularly visible in 1987, one of the record warm years (see Table 9). This is not as visible if we only consider land-based temperatures. Here there was warming even in mid-latitudes (see Fig. 19) - counterbalanced by cooling over the oceans. Once again we realize how important it is to look at the entire temperature record, land and oceans, if we wish to arrive at an observational record which can be used for comparisons with greenhouse predicted temperature changes. In the Southern Hemisphere however, there has been a more uniform warming, so that in reality we have

Table 9: Northern hemispheric surface temperature departures between 1976 and 1989 separated into tropical (0 - 30° N) and extra-tropical (30 - 90° N) regions. The base period is 1951-1960.

1976 1977 1978 1979 1980 1981 1982

0-30° N 30-90° N

-0.1 -0.4

0.2 0.0

0.2 -0.2

0.2 -0.2

0.3

-0.1 0.3 0.5

0.2 -0.2

1983 1984 1985 1986 1987 1988 1989

0-30° N 30-90° N

0.3 0.1

0.1 -0.1

0.0 -0.2

0.2 0.0

0.6 -0.2

0.4 0.2

0.1 0.2

Source: Institute of Meteorology, Free University of Berlin, Germany.

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Figure 20. Climate simulation using a transient, coupled ocean-atmosphere climate model employing "realistic" trace gas increases since 1958. Shown is the modeled temperature increase since 1958 as a function of time and latitude. Source: Stouffer et al., Nature, 1989.

to speak of a divergent trend between the Southern Hemisphere and the Northern Hemisphere, especially in the 30 years before the mid-'70s. On the other hand, if we consider land-based trends over the Southern Hemisphere for a moment, a look at the globe tells us that most of the land mass of the Southern Hemisphere is within 30-35° of the equator, so that we may count almost the ent- irety of the Southern Hemisphere land mass as low latitude or tropical. Scientists have now found out, very much in line with what we said above, that warmth over the Southern Hemisphere land mass is very highly correlated with warmth in the tropics, and therefore warmth in the Southern Hemisphere (landmass) is to a very large extent a reflection of warmth in the tropics.

Nonetheless, there has been significant warming even over the Southern Hemisphere oceans in recent decades (see Fig. 16), but not too much can be said about temperatures there in mid-latitudes. It remains doubtful, however, whether the Southern Hemi- sphere temperature rise can be explained in terms of the greenhouse theory, because the oceans, due to their thermal inertia, are least expected to manifest a greenhouse effect.

Some scientists think that sulfur emissions from fossil fuel burning, which occurs mostly in the Northern Hemisphere, might be responsible for the relative cooling of the Northern Hemi-


sphere. Indeed, sulfur, which provides for cloud condensation nuclei (CCN), might have been responsible for some of the cooling over the oceans, but it probably has to be ruled out as a cause for cooling over the continents.

Furthermore, sulfate aerosol, which forms from sulfur dioxide emitted into the atmosphere, may also have contributed to a cooling, at least partially off-setting the greenhouse effect.

However, sulfur emissions in the ICs increased only relatively slowly after WW II, peaked in the 1960s, and have been declining ever since, even though global emissions went up. Most of the increase occurred over Asia. Since sulfur compounds have an atmospheric residence time limited to only a few days (contrary to greenhouse gases), any cooling effects should essentially have been confined to the source regions and some distance downwind. In addition, if the sulfur argument holds, sulfur emissions should have caused a pronounced cooling in the industrialized regions of the Northern Hemisphere during the first half of the century, when they went up from close to zero to half their present value. Since we know that a large warming did in fact occur - instead of a cooling - the sulfur-climate relationship remains somewhat speculative at this point.

In any event, if we now pause and reflect for a moment, we realize that the pattern of the most recent warming is certainly not the one we would expect from climate model predictions: i.e., large warming at high latitudes and small warming at low latitudes. The recently observed pattern is the contrary (see Table 9 again). At high latitudes, there is even some continued regional cooling, which runs completely counter to model predictions.

However, just to show you how complicated things are, we thereby implicitly assume that the so-called transient response, i.e., the way climate evolves as trace-gases slowly build-up in the atmosphere, is the same as the equilibrium response, but at a smaller amplitude. As some recent modeling results suggest, this may not be the case. Due to complex feedback mechanisms between the oceans and the atmosphere, the geographical pattern of the warming may be different from the eqilibrium warming over decades, and in fact it may even cool at high latitudes in the Northern Hemisphere, and therefore create a warming pattern resembling the observed one. One example of such a calculation is shown in Fig. 20.

At this point it is too early to view the results of the more advanced transient models with any confidence. We could ade-

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quately account for the recent warm spells as a lawful result of the El Nino phenomenon without resorting to them, and there is currently no theory which could relate an increase in occurence of the El Nino to a greenhouse effect.

Moreover, we recall from Chapter 1 that the additional, man- made greenhouse effect should be least effective in the tropics because of the large overlap between water vapor and carbon dioxide there, which is why we expect the smallest warming in the tropics - at least in lower atmospheric layers. This might not be the case with other greenhouse gases, however, which are active in different spectral regions, and in upper tropospheric regions in the tropics.

Therefore, summing up, unless we are prepared to believe that the most recent warming is a greenhouse warming essentially restricted to the tropics, which appears to be in clear contradiction to the model predictions, we must reject the claim that the warmth of the 1980s is a proof of the greenhouse theory, or at best a strong piece of circumstantial evidence in its favor, for the following reasons: 1. On a formal basis, a spike in the temperature curve is no proof

of a climatic change. 2. The pattern of the warming is completely different from that

predicted by the models, unless the warming pattern of the transient response is very much different from the eqilibrium response.

3. More fundamentally, the warming must very likely be attributed to causes other than the greenhouse effect.

Summer Recess For The Greenhouse Effect

So far we have only looked at the trend of annual average temperatures, but we have not yet paid any attention to the intra-annual pattern of the warming of the past 140 years; in other words, we have not analyzed the question of whether the warming occurred more or less uniformly, distributed throughout the year, or whether it was concentrated in one or several particular seasons.

We remember from page 59 that over the US, the warming expected for the summer months was almost as large as for winter, whereas in the global average, wintertime warming is supposed to be noticeably larger than summertime warming.

The seasonal distribution of the warming is of particular relevance, since almost all of the envisioned negative impacts thought


Figure 21. Temperature trends over the continents of the Northern Hemis- phere since 1850, differentiated by season. The smoothed line shows 10-year averaged values. Source: U.S. Department of Energy, Report DOE/ER-0235,1985.

to be associated with global warming are tied to summertime warming. Clearly, one might expect the increase of an average summertime maximum temperature, from 85° F to 92° F, to have some kind of an adverse impact on agriculture and human comfort. On the other hand, it is not likely that many people in Minnesota

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would complain if the average wintertime minimum went up from -10° F to -3° F.

Let us therefore take a look at the seasonal pattern of the warming of the last 140 years (Fig. 21).

Much to our surprise, we see that almost all the warming in the land-based record is concentrated in the winter months and no warming whatsoever has occurred in summer. This is true not only on a global (or Northern Hemisphere) average, but also over the US, where we must in fact acknowledge that it has been cooling over the last 60 years. The same is true for other areas of the mid-latitudes, for instance Europe. In Europe, a decrease in summer temperatures can be deduced even from long-term thermometer records reaching back to the middle of the 18th century. This is all the more surprising since the greenhouse community is quite sure that a greenhouse warming should first be detectable in mid-latitudes in summer. But the warming we did observe has largely been a specific winter warming, whereas summer temperatures did not rise at all. This obviously raises questions as to the underlying causes of that warming, restricted to the winter half of the year: the greenhouse effect does not take a summer recess.

Everybody's Favorite: The Drought Of 1988

Now let us direct our attention to the third claim, the one that really had a big impact on public debate in the US: The drought of 1988. There have been a number of claims that the drought of '88 was, if not the final proof, then a very strong piece of circumstantial evidence in favor of the greenhouse theory, much like the warming of the '80s. To make one thing clear right away: to everybody who could read a climatological data table, let alone clima- tologists themselves, this was a hair-raising statement, and clima- tologists did not know whether to laugh or to disbelievingly bury their faces in their hands - but the public and media alike loved it anyway.

Now let us find out why this was probably the climatological "Edsel" of '88. First of all, we return to our central hypothesis of what climate is: Namely the long-term average of a climatic parameter, and climatic change is the long-term, lasting change of a climatic parameter. A run of cold years, hot years, dry years is a short-term climate variation, and not a long-term climatic change. This alone would almost be sufficient to refute the claim that the drought of '88 was due to the greenhouse effect.


However, as we have seen, the frequency and severity of droughts is expected to increase in a greenhouse scenario - which is the basis of the claims regarding the 1988 drought. Let us then analyze the drought from two different angles:

1. The historical climatological perspective and, 2. The causal perspective

Figure 22. Climate trends over the USA since 1895. The figure shows mean annual values of temperature and precipitation. Source: Karl, Climate Change, 1988.

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1. The historical climatological perpective Believe it or not, bad droughts are a normal part of US climate

in general, and of the Great Plains in particular. This is amply illustrated in Fig. 22 and Fig. 23, which show annual and seasonal temperature and precipitation trends over the US since 1895. Here, we see droughts as humps in the temperature and dips in the precipitation curve, because, as we have seen, droughts are - for most practical purposes - periods of hot summer weather with little or no precipitaion.

The big droughts occurred in the 1930s (the infamous Dust Bowl years, remember The Grapes of Wrath?) and the 1950s, or more precisely, 1934-1936 and 1952-1954.

The period following 1954 was conspicuously devoid of any major droughts and notably the '70s and '80s were characterized by a long string of predominantly cool and moist summers, interrupted only by a drought over the southern plains in 1980 and a drought in 1983, but there have been mainly cool and moist summers for decades, particularly over the nation's mid-west and the corn-belt. Nobody was yelling "greenhouse!" then.

But when 1988 arrived, and the country's mid-west was hit by the first major drought in 34 years, it had to be the greenhouse effect. It is hard to imagine that even a dyed-in-the-wool greenhouse proponent seriously believed that!

Obviously, from the climatic history of the US, there is no indication whatsoever that climatic changes of the type predicted by the models have occurred in summer over the past decades, and that the drought of '88, however extreme it was, can be seen as anything but a fluke of natural variability in the workings of the climatic system.

Midwesterners may indeed have second thoughts about those claims now that they have had to suffer through, or possibly enjoy, a predominantly cool and cloudy summer in 1989 and 1990, very much unlike the one of 1988.

It only goes to show that one should not extrapolate a short- term up-trend into a future long-term trend - a particularly suspect venture, when the existing longer term trend points downwards (see Fig. 22 and 23). 2.The causal perspective.

According to model calculations, droughts should increase as a result of the general rise in summer temperatures under a scenario of relatively constant precipitation, which has not materialized over the US so far.


Hence, there should have been (and should be in the future) an increasing frequency of those situations, where, due to increasing evaporation, soil dryness increases simply as a result of higher temperatures, but not because of concurrent changes in the atmospheric circulation pattern.

However, scientists have been able to show that the drought of '88 was not due to a general rise of global temperatures, but instead to an unusual change in atmospheric circulation patterns over and around the North American continent, which was temporary in nature and has since been reversed. The major feature of that change was the very persistent recurrence of high pressure areas over the central US and the hot, dry and sunny weather commonly associated with high pressure areas in the summertime.

Any greenhouse effect, if it was (hypothetically) present, may only have caused an additional warming, increase a high from 90° to maybe 91°, if that much, but it was certainly not a fundamental or even minor cause of the drought.

We must therefore reject the contention that the occurrence of the 1988 drought was in any way related to the model-computed greenhouse effect for the following reasons: 1. The drought was due to a temporary, anomalous change in at-

mospheric circulation patterns over North America 2. Climatic history shows that droughts are part of normal climate

variations in the US. The first major drought in 34 years cannot be taken as a sign of the greenhouse effect if the preceding 34 years were conspicuously devoid of any major droughts.

3. Moreover, long term trends of US summer temperatures show no indication whatsoever of the warming that the models predict. Instead, there appears to be a cooling over the past six decades, which clearly contradicts model predictions. We may add here that, while the US was hit by one of the worst

droughts ever, other regions of the world, e.g., Britain, recorded one of the wettest summers on record, and in northern Japan there was widespread failure of the rice crop - caused by an unusually cool and rainy summer: Facts, which are preferentially overlooked by the greenhouse proponents.

Looking For Clues

We have now analyzed the global temperature record, differentiated by annual and seasonal averages, and we have concluded that, in the global record, we only see a fraction of the modeled

Figure 23. Climate trends over the USA since 1895. The figure shows mean seasonal values of temperature and precipitation. Source: Karl, Climate Change, 1988.

temperature rise since the middle of last century, and furthermore that there has been no temperature increase at all in the summer, the season a greenhouse effect should be first detectable. More su- prisingly, in the US, there has actually been cooling over the last 60 years.

Before we now look at other climate parameters on a global scale, for the sake of completeness we will see if there has been a

100 GLOBAL WARMING


temperature increase over the US in the remaining seasons which is compatible with model predictions.

The temperature trends for the US are shown in Fig. 23. In this set of data, which begins in 1895, no appreciable temperature change compatible with model predictions can be discerned. If one considers only the last 60 years, temperatures have actually decreased quite noticeably, particularly over the country's mid- west and in winter. The relative coldness of the US during the last decades, compared to earlier decades, reflects the general cooling trend of middle and high latitudes of the Northern Hemisphere, which has already been shown in Table 9. Neither of these observations lend much credence to model predictions of a general and widespread warming over the US.

Let us now search the climatic record for further clues for - or against - the greenhouse effect on a worldwide basis. We will do this by looking at some of the major changes thought to have been caused by a greenhouse warming and comparing predictions with observations.

In doing this, we assume that the pattern of the transient response of climate to increasing trace-gases is similar to the equilibrium response, but at a lesser magnitude, as is done in almost every major study devoted to the subject. However, as we cautioned on page 93 that may not be correct, and the transient response may be different from the eqilibrium response; therefore some of the clues identified in favor of the greenhouse effect may turn out to be no clues, and conversely, some of the clues rejected may turn out to be evidence in favor of the greenhouse theory after all. It appears as if we are treading on treacherous, highly speculative ground.

On page 57, we already identified some of those expected major changes and we will now direct our attention to them. Let us then look at:

1. The precipitation record 2. The sea level record 3. Extreme weather and climate events

1. The precipitation record According to climate model predictions, precipitation world-

wide should increase under a scenario of rising trace-gas levels and the warming caused by it, basically as a result of increased evaporation from water and land surfaces and the attendent increase of atmospheric water vapor content. Those increases should be most pronounced poleward of 35° of latitude, while in

Figure 24. Trends of precipitation in lower and mid-latitudes of the Northern Hemisphere since 1850. Shown is the relative variation where values below .5 indicate precipitation amounts below long-term means and values above .5 indicate amounts above long-term means. Source: After Bradley et al., 1987.

the subtropical belt, no major changes are expected. Clearly then, even if one observed an increase of precipitation,

it would not be an independent proof of the greenhouse effect, since, in the model calculations, such an increase would princi- pally be tied to a warming of the oceans, which had to occur before or simultaneously with the increase in precipitation.

Other than increasing atmospheric water vapor, an increase in precipitation could also be brought about by an intensification of precipitation generating processes, as for instance the strength and frequency of rain-bearing storm systems in mid-latitudes.

Looking at the precipitation record, (see Fig. 24) we realize that precipitation in mid-latitudes has indeed increased during the last four decades, just as the models ordered. Could this be a proof of the greenhouse effect then?

Well, certainly not, because even if the increase were tied to temperature, it would only be an echo-effect of the temperature record, which we have already shown to be only marginally related to the greenhouse effect.

But there is more. Since the 1950s, the oceans in mid-latitudes have been going through a cooling phase, which covers the Paci- fic north of about 25° and the Atlantic north of about 40° latitude. Hence, the increased precipitation in mid-latitudes cannot be the

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Figure 25. Northern limit of the West African monsoon between the early 1950's and the early 1970's. Source: After Bryson, 1974, and Lamb, 1988.

result of increased evaporation from warmer mid-latitude oceans, but must be attributed to different factors.

One of those factors may indeed be the increased frequency and intensity of storm systems alluded to above, which would be accompanied by intensified precipitation-generating mechanisms. Why? Because the intensity and frequency of storm systems in mid-latitudes is generally related to the temperature contrast between the equator and the pole: The stronger the contrast (or gradient), the more intense the storm systems become. Now, this temperature contrast has intensified in recent decades, particularly over the oceans, the main playground of most major storm systems. The intensification is a result of the lop-sided warming we have witnessed in recent decades (see Fig. 19): warming in low latitudes and cooling in high latitudes. As a result, storm systems grew more intense on the average and may have yielded more precipitation. It may be noted in addition that no major change in the equator-to-pole temperature gradient was expected according to the models, and that the observed intensification of the gradient - in conjunction with the pattern of the most recent warming itself - runs counter to climate model predictions. We may therefore conclude that an increase of observed precipitation in mid-latitudes of the Northern Hemisphere can not be explained in terms of the greenhouse effect, and that the actual, underlying causes of the increase in precipitation point against the greenhouse effect as a causal factor. Despite the fact that, according to the models, no decrease of precipitation is expected in the subtropical belt, it has

THE REST OF THE STORY \ 03

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frequently been argued that a decrease observed there (see Fig. 24), which is particularly prominent over the Sahel region of Af- rica, is due to the greenhouse effect. But much to the chagrin of greenhouse proponents, the beginning of drying in that region is coincident with the general global cooling, which began in the 1950s and which was most pronounced in the Northern Hemi- sphere.

Along with that cooling, there was a general slight shift of the atmospheric circulation belts to the south, which caused the Sahel (about 20° N) to be more frequently under the influence of the subtropical high pressure belt and dry northerly flow, instead of moist southerly flow from equatorial Africa. The northern limit of the moist southerly flow has receded steadily (see Fig. 25).

That shift to the south may partially be a reflection of the sout- hward shift of the "thermal center of gravity" towards the Southern Hemisphere we mentioned earlier, and which can hardly be explained in terms of the greenhouse theory, because the Southern Hemisphere is mostly covered by water, where we would least expect to see a greenhouse effect.

2. Rising Sea Levels Rising sea levels are one of the major causes of concern associa-

ted with the greenhouse effect. Indeed, some increase in sea level has been observed during this century and has been interpreted as a piece of evidence in favor of the greenhouse theory.

We first of all recall that rising sea levels are thought to result mainly from a warming and thermal expansion of the oceans, and even if observed, cannot be viewed as an independent piece of evidence, since in that case they would be an echo-effect of the rising temperature, much the same as with precipitation.

We then recall, secondly, that the oceans in mid-latitudes of the Northern Hemisphere, where most of the sea level gauges are located, have cooled in recent decades, so that, on the face of it, it is hard to imagine how cooling oceans may be associated with rising sea levels in terms of the greenhouse theory.

Furthermore, and most importantly, much of the sea level increase has been deduced for a time period when SSTs did increase, namely from about 1910 to 1970.

However, we recall from Fig. 15 and 16 that SSTs did decrease drastically between 1890 and 1905, so that it is somewhat suspect to restrict an analysis only to that time interval where one might expect to arrive at the desired result: Namely a parallel course be-


tween rising SSTs and rising sea levels. What kind of sea level trends one would deduce if the analysis were extended back to the time before 1890, when SSTs were about as warm as they are today, is an open question.

Furthermore, since most of the SST rise (and possibly the associated sea level rise) occurred in the first half of this century, it cannot be blamed on the greenhouse effect anyway for reasons stated earlier.

In addition, the spatial distribution and accuracy of sea level gauges is severely limited prior to 1900; in essence, very few data from the North East Atlan- tic and the Baltic Sea are considered accurate.

After making allowance for tectonic movements of the earth's crust, i.e., the natural rising and sinking of the earth's surface, which may falsely suggest either a rising or sinking sea level, some researchers recently concluded that the observed sea level rise can be attributed only in a small part to oceanic warming and should rather be viewed largely as a result of glacial melt.

However, we know that at least in high latitudes of the North- ern Hemisphere such a melt-off was highly unlikely in recent decades, because it was cooling there (see Fig. 19).

There has been some warming at high latitudes of the Southern Hemisphere in recent decades, which may have caused some glacial melt there. Yet we know from page 71 that the net effect of a small warming around Antarctica is not a loss of ice, but a gain. It is therefore difficult to imagine that even the observed warming

Figure 26. Glacial advances and retreats in the Swiss Alps between 1890 and 1984. Between 1950 and 1980 the number of glacial advances in- creaseeed. Source: After Schuepp and Gensler, 1986, and Lamb, 1988.

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at high latitudes in the Southern Hemisphere did make a contribution to a sea level rise.

Furthermore, at least over the Alps, there has been, if anything, an advance of glaciers since the mid 1960s (see Fig. 26) and not a retreat, which would be required for an increase in melt water made available to the oceans.

Again, the bulk of the observed glacial melt did occur in the first half of this century, and as we have repeatedly pointed out before, all those processes - be they warming seas, retreating glaciers, rising sea levels, or the warming in general - as far as they occurred in the first half of this century, cannot be ascribed to the greenhouse effect because they occurred before trace-gas concentrations went up so rapidly.

We must therefore conclude that the sea-level record is no more of a factor supporting the greenhouse theory than the temperature record itself.

3. Extreme Events One favorite sport of the media and greenhouse proponents

alike is to link the occurrence of extreme weather and climate events to the greenhouse effect.

In fact, it appears to be standard procedure now-a-days, that whenever some extraordinary event occurs, it is immediately blamed on the greenhouse effect.

In doing so, a screening procedure is usually applied, which picks out only those extremes which fit the greenhouse bill, while the others are left out.

The same goes, by the way, for a number of scientific publicati- ons, all designed to "prove" the greenhouse effect, thereby falling victim to what is called "scenario fulfillment"; i.e. "the inadvertant distortion of data flow in a subconscious attempt to make them fit a preconceived scenario".

Needless to say, this is highly unscientific. But obviously, some researchers fail to realize that the point at issue is not whether data can be explained by - or is not contradictory to - the greenhouse theory, but rather to ask if that is the only and the best possible explanation, because we are justified in speaking of a relationship between some observed phenomenon and the greenhouse effect only if other explanations can be excluded, or rendered unlikely.

Here is an area where an upgrading of proper and defensible scientific attitude is badly needed, not to mention the media's attitude.


We have already dealt with one such example of extreme events, i.e., the American drought of '88, which we have accounted for, as far as the greenhouse effect is concerned.

And we could do the same thing with all the remaining claims. Just for the sake of completeness, and not to bore you to death, we will again mention our guideline for climate: The long-term average of a climate parameter, and a climatic change, a long-term lasting change of any such parameter.

If we take as examples for such extreme events the number of days with temperatures above 90° F, the number of days with rainfall above 5", or the number of hurricanes in a hurricane season and so forth, we must obviously apply the same criteria to the extreme events which we have applied to temperature or precipitation alone. In other words, we must ask whether the frequency and/or severity of those events changed over a climatically relevant time scale, which is about 30 years. We cannot, as we have shown above, draw the conclusion that one particularly heavy rainfall, drought, storm or severe winter constitutes a climate change if it is only an isolated event; or even if it occurs in a run of years, if that run of years is short compared to a climatic base period, or is replaced by a run of years of countervailing character. Nothing in climatology is more nonsensical than the extrapolation of a short-term trend into a long-term trend.

In the summer of 1987, Chicago (and other areas of the great Plains) were hit by several intense rainstorms, which produced close to 10 inches of precipitation within 24 hours and caused severe flooding. If anyone had then concluded that we are now headed for rainy summers, the drought of '88 should have taught him a lesson. If any one had concluded in the summer of '88 that we are now headed for hot summers, the cool summer of 1989 would again have taught him the same lesson: Never extrapolate a short-term trend into the future.

As far as extreme events are concerned, we must conclude that we can speak of a climate change only if they occur in an increased frequency over a climatically relevant time scale. If they do not, they are climatically, and in terms of the greenhouse theory, mean- ingless - particularly, if they are accompanied by climatic events of opposite character in other parts of the world, which would be contradictory to the greenhouse theory anyway.

There are no indications that the warming climate of the last 100 years has been accompanied by an increase in extreme events; the opposite seems much more likely. From all we know, it appears as

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if the colder episodes in former centuries were the ones with many more extremes in climate, while the relatively warm climate of the 20th century has been mostly benign.

Time Out I

In our analysis of the greenhouse theory, we have contested a number of claims made in public debate about global warming and the greenhouse effect.

We were able to separate spurious claims from those supported by climate-model predictions, and we were further able to test some of the model predictions against reality. We had to conclude that all we can say at this point is that there has been some warming over the past 100 years, a warming which is considerably less than the model-predicted warming. In particular we refuted the two major claims that the most recent "global" warming and the occurrence of the '88 drought is related to the greenhouse effect, since both could quite clearly be attributed to causes other than the greenhouse effect.

The question which obviously needs to be answered is: There has been warming over the last 100 years, although much smaller than could be expected from model predictions, but is that warming due to the greenhouse effect, or is it due to different causes? We will analyze this problem shortly.

Even now we have to concede that many concerns about the future direction of climate may be put into an entirely different perspective by the realization that we may be dealing with only one half to one third of the projected temperature increase thought to result from a CO2 doubling, which, as we have seen in our future trace-gas scenarios, may not even occur until well into the 22nd century. At this point we might ask what all the fuss is about?

Greenhouse proponents have argued that, even if the observational data do not fully support - even contradict - their claims, they still believe the large warming predicted by the models will occur, since we have only been within the range of natural variability of climate so far, where neither a warming nor a cooling would be a proof or counterproof of the greenhouse theory. For example, as we pointed out before, even the fact that the warming in this century fell drastically short of greenhouse expectations, it could still be "explained away" by assuming that a large natural cooling occurred, which counteracted the greenhouse induced warming.


The line of argument then continues with the claim that we cannot afford to wait long enough to see evidence of the greenhouse effect, because when we finally have proof, it would be too late. Therefore, we have to act now.

Before we go into an analysis of this proposition, let us examine the role natural factors might have played in causing the warming - or the proposed hypothetical cooling - of the last 100 years. We will also see whether there were warm climatic periods in earlier centuries and millenia - obviously due to natural causes at those times. In addition, we will also attempt to estimate what a warmer or a colder climate than today meant then to nature and human activities. The historic precedent may give us some clues for what to expect from a warmer climate. Will it be "better" or "worse"?

5.

The Longer View: Factors Other

Than Trace-Gases

That Affect Climate

n the preceding sections, we analyzed trends and patterns of climate parameters and attempted to relate them to the postulated man-made increase of the greenhouse effect due to

the emission of various trace-gases. In doing so, we acted as if trace-gas increases were the only factor that could have affected climate, and deliberately neglected other parameters which might also have had a bearing on climate over the last century. Now we are going to identify some of those other factors which also affect climate and which may indeed explain some, if not all of the observed warming of the last century.

Implicitly, we have already come to the conclusion that natural factors must be important when we realized that most of the warming this century occurred at a time when it could not have been caused by trace-gas increases - i.e., before WW II, when trace-gas emissions were comparatively small, but the observed temperature increase was much too large to be explained by that trace-gas increase. Hence, natural factors must have been at work causing the earlier temperature increase. We will now attempt to identify some of those factors.

The Urban Heat Island

Once more we will first look at the land-based temperature record of the last 100 years, which we have accepted so far at face value, and briefly discuss the possibility that some of that temperature increase of the 20th century is caused by a phenomenon called the "urban heat island".

The urban heat island phenomenon is due to the fact that built- up areas such as cities are always somewhat warmer than the surrounding countryside, because the concrete-asphalt-brick jungle attracts and stores more heat and evaporates less water in sum-

I


mer than the surrounding countryside, and in winter additional warming is produced by waste heat from various human activities.

Now, weather observing stations, which were located at the outskirts of towns around 1900, gradually became located right in the middle of towns as the cities grew out around them over the following decades, storing and producing the urban heat and thereby warming up the neighborhood of the weather observing stations. Rising temperatures at those stations may be a reflection of the growing cities around them, but it is no indication of generally climbing temperatures, because that warming was restricted to the cities themselves. If that "urban heat island" effect is accounted for, rising temperatures may then not indicate a warming climate but only growing cities. It is generally believed that this effect has been factored out of the temperature record, but some controversy is still smoldering over whether it has been sufficiently accounted for. For example, scientists have been able to show that the urban heat island is not only confined to bigger cities, but can also be observed in small towns - a fact a number of studies overlooked.

Watch Out For The Volcanoes!

While scientists certainly do not know all of the factors which might have a bearing on climate, several factors thought to have an impact on climate variations on the time scales of concern to us are known.

We will discuss them now and begin with the one which is probably least important - on the time scales relevant to the greenhouse problem.

This is volcanic activity, which is important on time scales of 1- 10 years, but possibly even longer if there is an extended lull or increase in volcanic activity.

The direct impact on climate of a volcanic eruption is difficult to estimate, since much depends on the severity of the eruption, on how high up into the atmosphere volcanic material is blown, and on the chemical and physical properties of the material injected into the atmosphere by the eruption.

By and large, however, the impact will be a tropospheric and surface-cooling of the earth in the 1-3 years following a major volcanic eruption. The magnitude of global average cooling is mostly in the neighborhood of 0.2-0.5° F. Any protracted periods of volca-

Figure 27. Observed changes in the transparency of the atmosphere since 1882. Two recent major volcanic eruptions - Mount Agung in 1963 and El Chichon in 1982 - can be identified as marked peaks in this curve. Previously, volcanic activity was suppressed since about 1920. Source: George C. Marhall Institute, Washington D.C., 1990.

nic activity will therefore be generally cool, whereas any prolong- ed periods characterized by a notable absence of volcanic activity will therefore be generally warm, everything else being equal.

For instance, the relative coldness of the 1880s is partially blamed on the Krakatoa eruption in 1883 and the coldness of the 1810s, particularly "the year without summer", 1816, when freezes occurred in New England in July, on the Tambora eruption in 1815.

The 20th century, on the other hand, was characterized by a remarkable reduction of volcanic activity in the years following WW I, interrupted only by the Mt. Agung eruption in 1963 and the El Chichon eruption in 1982. The Mount St. Helens eruption in 1980 does not appear to have had a major global impact.

We therefore realize that most of the warming in the first half of the 20th century was accompanied by a marked reduction of volcanic activity, which basically persists to this very day (see Fig. 27). Only the recent eruption of Mt. Pinatubo is considered to be severe enough to have had some impact on global climate.

An obvious conclusion we can draw from this is that part of the observed warming during the last 100 years may be related to a protracted lull in volcanic activity - which would then reduce the share we could ascribe to the trace-gas increase and the greenhouse effect. However, it would be quite difficult to quantify the amount by which reduced volcanic activity may have contributed to the warming.

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What Heats The Earth? The Sun Of Course!

The most important factor, and unfortunately the least understood, is related to changes in solar brightness.

It has been known for quite some time that regular variations occur in the number of sunspots on the sun's surface, which have an average period of 11 years. In addition, large variations were observed in the amplitude, or number of sunspots, at peak years. Earlier this century, a number of attempts were made to relate those sunspot cycles to short-term climate variations - with almost no success at all.

Only a few years ago, a possible relationship between the 11- year solar cycle and another phenomenon which affects primarily the stratosphere, the so-called quasi bi-annual oscillation (QBO), has been discovered.

Although there are some quite interesting effects associated with solar-QBO processes which may explain some of the observed short-term climate variations and may indeed even have

Figure 28a. Scatter diagram of mean annual temperatures in Central Europe and sunspot numbers. Long-term averages between 1761 ans 1989. Standard zed values. The coefficient of correlation between the two variables is r =.71. Source: After data from Linke and Baur 1962 (and addenda)

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some merit in short-term climate forecasting, we are not concerned with short-term climate variations, and so we re-direct our attention to longer-term variations in the solar energy output - still short compared to the age of the sun - but within the time scales we are interested in: a few decades to a few hundred years.

Those variations have to do with differences in peak amplitude at different maxima of the 11-year solar sunspot cycle.

Researchers have noted that a very pronounced minimum of those peak amplitudes, the so-called "Maunder minimum", coin- cided with the coldest observed temperatures of the little ice age in the second half of the 17th century. Furthermore, another minimum early in the 19th century, the "Spoerer minimum", was also accompanied by significantly lower temperatures than in preceding decades (see the temperature and solar cycle record in Fig. 28a). Other researchers who analyzed various kinds of so-called proxy data, i.e., data indicative of climate variations, noted that a quasi 200 year cycle seems to exist in both solar activity and temperature on earth. This 200 year cycle has been confirmed by a number of other sources; some scientists relate it to gravitational variations between the sun and the solar system's largest planets, Jupiter and Saturn.

Whatever the reasons, if we compare the long-term trend of land-based temperature over the last 100 years to that of the sunspot numbers, some striking similarities appear (see Fig. 29), and the correspondence becomes even better when one considers SSTs alone.

In fact, if one attempts to statistically relate regional temperature records to the various factors we have been dealing with so far over the entire length of available record, which is about back to 1750, the long-term average of sunspot numbers has a close relationship to temperature (see regression estimate in Fig. 28a)

Even though the physical mechanisms through which solar activity may influence climate are unknown (the variations in solar energy output are extremely small, which is why many scientists are skeptical about solar-climate relationships), it is no surprise to learn that some scientists conclude that the warming we have seen this century may to a large extent have been caused by solar variations alone, and that the postulated greenhouse effect may only have played a minor role, or at least not a significantly greater role than solar variations. We did implicitly arrive at a similar conclusion earlier when we found out that the very largest part of the observed temperature increase of the last 100 years occurred


Figure 28b. Variation of yearly averages of sunspot numbers and tropospheric temperatures over mid-latitude oceans of the Northern Hemisphere, between 1966-1990. The coefficient of correlation between the two data sets is r=.76.

during the first half of this century - at a time when it could not have been caused by a trace-gas increase.

This conclusion comes on top of our earlier realization that the temperature increase this century was also accompanied by a lull in volcanic activity, which further reduces the possible role the greenhouse effect might have had.

Clearly then, it now appears foolish to believe (and to claim) that the warming we have experienced over the last 100 years has largely or even entirely been caused by the greenhouse effect. Greenhouse activists may take some additional (cold) comfort from the fact that the years 1989 and 1990 were years with some of the highest sunspot numbers ever (and the period 1950-1989 was the 40 year period with the largest number ever since records began) - putting a further damper on their claims that the 1980s were the decade when we finally saw the greenhouse effect. When considering annual averages of tropospheric temperatures, as we did before in Fig. 19, temperatures in the mid-latitudes of the Northern Hemisphere seem to have closely followed solar activity since the 1960s, which is when this data-set began (see Fig. 28b). Therefore, possible solar-climate-relationships should not be so easily dismissed.

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Was There Climate In The World Before 1880?

Next, we wish to put climatic events of this century into a larger perspective, because climate did not begin in 1880 or 1850 after all, as one might have been led to believe by the greenhouse debate, which likes to restrict discussion climate to those last 100-140 years.

It would be interesting and possibly instructive to find out how climate behaved in earlier centuries. That might enable us to draw some conclusions about climatic variations in the present century.

Let us take a look then at historical temperature records dating back to the days before 1850, the time before relatively reliable glo-

Figure 29. Comparison of long-term averages of sunspot numbers and average global temperatures from 1885 to 1985. Source: George C Marshall Institute, Washington D.C, 1990.


bal, or at least land-based temperature records became available. The first and foremost problem we face here is that temperature

records from those early days are few and far between. Nevertheless, some fairly reliable "thermometer" records do

exist back to about the middle of the 18th century, and in a few cases even to 1700 and a little earlier. Those records are mostly from various parts of Europe and from the eastern U.S. Unfortu- nately it is difficult to ascribe a global representativeness to them with any amount of certainty, because, as we found out a little earlier, a tropical or global trend may run counter to a mid-latitude or any other regional trend (see page 91, Fig. 19., and Tab. 9).

The oldest thermometer record is the "Central England Re- cord", which begins in 1660 and is shown in Fig. 30.

One of the interesting aspects of the Central England Record is that it ran fairly parallel to the global trend between 1880 and 1970, and it is tempting to use it as a surrogate for the global trend prior to 1880. However, because of the likely unrepresentativen- ess of regional trends over the long haul this will not be done here.

But it may still be surprising to see wild swings in this temperature record in the days before 1850. There were in fact periods when it was considerably warmer than today - despite claims that the current warmth is due to the greenhouse effect. Those warmer periods can also be detected in temperature records from other parts of the world.

Obviously, it can become warm on earth even without the additional man-made greenhouse effect - which once again empha- sizes our argument that there are other factors which have a warming effect on climate and which have so far not been considered in climate model forecasts.

Let us briefly raise one point again which we have repeatedly hammered on throughout this book. This is the nonsensical extrapolation of a short-term trend into a long-term trend. We can pick out several portions of the Central England Record when temperatures rose almost continuously for decades. Any observer back then who had simply extended that trend into the future, would invariably have woken up one day to a bad surprise. It did not become any warmer; instead, the trend reversed and it became colder.

What we learn from this is: Through the centuries, the climate changes and fluctuates continuously. There may be decades which are predominantly warm while others are predominatly cool, but over the long haul - and here we are talking about hun-

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dreds of years - it appears to fluctuate around a center of gravity, which is the very long- term climatic average. And all this happens because of the combined, intertwined action of natural parameters. We may now have a feeling that it is not so easy to separate natural factors from those due to man's activities when we try to explain the observed temperature trend of this century, because we do not know all of those natural factors. To deepen our appre- ciation of natural climatic variations of the past, we will attempt to look back even further to the days before direct thermometer measurements were available.

One might ask how it is possible to obtain data on temperature and climatic fluctuations without direct measurements. Well, it is difficult and becomes increasingly tenuous the farther back one looks.

There are a number of sources from which indirect inferences about climate can be made: One such source is old historical records of items as diverse as descriptions of extreme climate events, river levels, harvest yields (including taxes and prices), which date back to the Middle Ages in parts of Eu- rope. It has proven possible to relate data as bizarre as a wine quality index from the wine-growing provinces of Southwest Germany to the average summer - or growing season - temperature with fairly good success, and tern-

Figure 30. Temperature trend in Cen- tral England since 1668, 10-year running means. Source: After Manley, 1974.


perature and the general character of the summer seasons has been reconstructed back to the Middle Ages.

Some very old records from ancient Egypt permit conclusions about the water level of the Nile as far back as 2000 B.C., which is of utmost economic importance for that country. Some very interesting aspects of climatology revolve around those indirect methods of probing into climates of the past.

Even direct historical records, fairly abundant from medieval Europe, allow some conclusions about the climate back then. On the basis of historical records, it has been possible to reconstruct a climatic history of Switzerland back to the early Middle Ages. Needless to say, there were periods, decades, when the climate was much warmer than at present, and some of the most graphic examples include the year 1540, when people were bathing in the Rhine river at Christmas, or one year when the grape harvest began in July instead of September. If the same extremes occurred in our time there would be a deafening chorus of Greenhouse! Greenhouse! resounding through the land.

Furthermore, and more importantly, it is possible to reconstruct climate from so-called proxy data, that is, data indicative of climate variations. Some of the most widely used sources of proxy data are tree-ring records, lake sediments, (and lake levels), and pollen concentrations.

Large amounts of data have been collected from around the world; and while the margin of error is quite substantial, when this data is aggregated to emulate a "global" temperature trend, certain inferences can still be made about the climate of earlier centuries and even millenia: 1. There was a period from about the late Middle Ages, 1600 A.D.,

to the middle of last century, when climate in the middle and high latitudes of the Northern Hemisphere was generally 1-2° F colder than today. This period is often referred to as "The little ice age".

2. Between 1000 and 1200 A.D. there was a period when climate was close to 2° F warmer than today. It is called the "Medieval climate optimum".

3. Around 4000 B.C. there was a period when climate was 2-4° F warmer than today. That period is called the "Altithermal", "Holocene" or simply "Climate optimum". Climate during those periods was profoundly different from today's. Historically, it is well established that the cold periods of the little ice age - which was not cold throughout, but occasionally

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interrupted by rather warm decades, as in the second half of the 18th century - caused substantial problems to most human endeavors: Agriculture, a livelihood for a much higher percentage of the population than today, was severely hit, since food was almost entirely locally grown and consumed. Wars were fought over the supply of grain. In one instance, in 1771, Frederick the Great mili- tarily occupied territories in neighboring Poland and confiscated the Polish grain harvest to secure the grain supply of Prussia after all remaining options to peacefully make up for the Prussian crop failure turned out to be of no avail.

During the medieval climatic optimum, the Vikings set out to discover and settle Greenland, which was, at that time, as the name suggests, green - at least in coastal areas. Most of the settle- ments had to be abandoned one or two centuries later when climatic conditions worsened, signaling the advent of the little ice age.

It appears to be fairly well established that during the climatic optimum 4000 B.C. summer temperatures in Europe were at least 4° F higher than today. At the same time, today's hyperarid regions of the Middle East and Northern Africa were substantially wetter than today, a situation which must have lasted long enough to turn Cyrenaika into the bread basket of the Roman Em- pire, and which provided a climate sufficiently moist to support large forested areas in Palestine until the Romans used that wood for ship-building, much in the same way the Spaniards did a mil- lenium and a half later in the Iberian Peninsula. The results of that deforestation have not been overcome to this day, which provides a graphic example of the way man alters his natural surroundings, and the climate along with it, at least on a regional scale.

Obviously, there are long-term factors at work other than the greenhouse effect which have a bearing on climate and that can cause swings in climatic conditions as large or larger than we have witnessed over the past 100 years.

We do not consider factors here which may have caused the ice ages, when earth's temperature was 7-9° F lower than today, and which have been related to variations in earth's orbital parameters, and which only enter the game at time scales from several thousand to 100,000s of years. And we will also not consider even more ancient climate variations covering geological times.

The causes of these very long-term climate variations do not have a bearing on the present debate, because we are only concerned with climate variations on time scales of a few decades to


a few hundred years - the time scale on which greenhouse gases are supposed to make their impact felt.

Summing up, we should realize at this point that cold periods in climatic history are equated with the ones causing immense problems - at least within the cultures located in the mid-latitudes of the Northern Hemisphere, while warm periods are generally thought of as more benign, element, and favorable to nature and almost all human endeavours, which is why they are named "climatic optima". Even subtropical regions enjoyed a more favorable, i.e., cooler and wetter, climate then.

On the basis of those historic precedents, it appears difficult to accept claims that a warmer climate means catastrophic change for Earth. From what we know about climate history we can only conclude that a warmer climate - warmer by up to 3-4° F - has been beneficial and not detrimental. This sheds a different light on the impact of a warmer climatic future. It may not be so terrible after all, even if as large a warming occurs as predicted. But will it?

Time Out II

If we recall our earlier conclusion that the climatically relevant warming of the last 100 years was only of the order of 0.6° F, averaged over continents and the oceans, to stress the point again, the role we may finally assign to the greenhouse effect in causing that warming may be reduced to a fraction of that - and to a very small fraction of the model-predicted 2° F, because we could not find any convincing evidence of a hypothetical natural cooling. On the contrary: the available evidence points to a natural warming.

Extending that conclusion to the model-predicted 5-7° F increase for a CO2 doubling means we should only expect a fraction of those 5-7° - possibly something in the neighborhood of, or even less than 2° F.

This is a very important conclusion which seriously questions the validity of the doomsday scenarios from the greenhouse activists.

However, their biggest headache is yet to come. Scientists have found out that a minimum in the 180-200 year solar cycle might occur sometime next century - possibly bringing a cooling of 1-2°F to our earth, thereby cancelling entirely any expected greenhouse warming, if it occurred at all.

They conclude, greenhouse effect or not, that the temperature of the earth next century could be very close to what it is now:

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Somewhat cooler, if the natural, solar induced cooling prevails, somewhat warmer, if the man-induced greenhouse effect prevails. Before we analyze the implications of those conclusions for the greenhouse and trace-gas reduction debate, let us first repeat and digest those results, and recall again briefly how we arrived at them: 1. We defined a temperature trend for the last 140 years which is

compatible with any meaningful definition of climate, comprising continents and oceans, and which can therefore be used for comparisons with model-predicted temperatures.

2. We determined temperatures increased by about 0.6° F, less than one third of what the best available climate models predict.

3. We analyzed long-term (as long as is relevant to the present discussion) temperature records, and found that there were periods as warm or warmer than today, which must have had causes other than the greenhouse effect.

4. From ancient climatic data we conclude that warmer periods were more benign to nature and human activities, which is why they are called "climate optima".

5. The warming of the 20th century occurred mostly in the first half, at a time when it could not have been caused by a trace- gas increase, but at a time of increasing solar and decreasing volcanic activity. Both factors would lead to a warming of climate.

6. The total contribution of the postulated greenhouse effect to the observed warming, which to begin with is only one third of the predicted greenhouse warming, must in all likelihood be even less than that one-third because additional natural factors are as likely or more likely to have caused the warming.

7. Any future warming thought to occur from rising trace-gas concentrations should then likewise be significantly less than expected.

8. Looking ahead 100 years into the future, any slight warming due to the greenhouse effect may very easily be counterbalanced by a possible natural cooling due to solar variations. We are now left with a situation where we cannot but realize

that the actual climatic warming is much smaller than the one predicted by the models. We find it hard to believe that a possible greenhouse warming this century has been cancelled by a natural cooling. We could not find any convincing evidence of a natural cooling. One way to reconcile the discrepancy between climate simulations and climate observations - other than assuming that the


models are right but the observations are "wrong" - is to assume that the models are overpredicting. They may be right about the effect as such - that is simple physics - but not about the magnitude. Strangely enough, when one follows the statements of most greenhouse activists, there is a steadfast refusal to even admit that such a possibility exists. They tend to argue that it is irrelevant with respect to the measures we should adopt to stave off global warming. Not quite: The measures to thwart a warming of 2° F in 2100 are of a decidedly different nature than those to fight a warming of 5°F in 2020. One can not help but think that it really is irrelevant to them whether a greenhouse warming already has occurred or how large the expected greenhouse warming will be, because the motivation behind initiating those measures is almost entirely unrelated to the greenhouse effect.

We will not go into this any further at this point; we will do so in depth later on. At this point, we will probe into the possible reasons for why the model predicted warming is so much larger than the observed one.

After all, those models are run by the world's best scientists in their respective fields; they employ the world's fastest and most expensive computers: why shouldn't they be right, after all? Well, they might be if they included all of the processes important to climate in their models.

Let us recall again what we said at the beginning: A model is only an approximation of a reality which is much more complex; and if there are significant processes in real climate not dealt with, or dealt with incorrectly in climate models, the model results might be incorrect.

Most scientists agree that there are two major areas where the model predictions might founder, and which we will therefore analyze in some detail:

1. The way the oceans are treated in the models. 2. The way clouds are treated in the models.

1. The oceans We saw earlier that the oceans assume a key role in both the car-

bon cycle affecting the atmospheric concentration of the most important greenhouse gas, CO2, and climate by acting as a sink and transfer medium for heat.

A significant part of the poleward heat transfer from equatorial regions is carried out by ocean currents. In the Northern Hemis- phere, those currents have been estimated to effect up to 40 per-

Figure 31. Model calculations of globally averaged surface air temperature employing the IPCC scenarios "A" (business as usual), - A (LSG) and "D" (CO" reduction to 50% of 1985 level by 2050) - D (LSG) and instantaneous CO" doubling (2 x C02 (LSG)) in the Max Planck - Institute of Meteorology, transient coupled ocean atmosphere GCM. According to this model, temperatures in coming decades will rise significantly less than projected by the IPCC calculations. Source: Max-Planck -Institute of Meteorology, Hamburg, Germany, 1991.

cent of that poleward heat transport. Any misrepresentation of those currents, which, to make matters worse, have a complex three-dimensional structure which is difficult to model, could very easily result in distorted climate model predictions.

However, there have been some encouraging attempts to grap- ple with the issue of vertical heat transfer in the oceans, and indeed, our earlier conclusion that temperatures should thus far have risen by approximately 2° F as a result of the greenhouse effect alone included some modeled "swallowing" of heat by the oceans. But was it enough? It is generally agreed that a number of issues, in addition to correctly placing the crucial ocean currents, are yet to be resolved in vertical heat transfer processes in the oceans. Quite obviously, it is of paramount importance to know how deep into the ocean heat will penetrate from the surface, and no less important, how fast that penetration takes place. One piece of evidence for why climate model-predictions have been so high in- tersects the heat penetration issue. Scientists employing physi-

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cally more realistic heat transfer processes in the ocean's surface layers found that oceanic warming between 1880 and 1980 should only have been approximately one third of what standard GCMs predict - therefore considerably closer to the actually observed oceanic warming since the 1850s - if there has been any warming at all. Nonetheless, incorporating realistic ocean modeling into standard GCMs remains a tricky issue for a variety of physical, mathematical and, primarily, computational reasons. It is generally agreed that a substantial increase in computing power is sorely needed soon to make any significant progress in modeling the impact of the oceans on climate and climate change.

There have been some encouraging signs recently of succesfully grappling with the oceanic issue in climate modeling by developing so-called coupled models; some of them do in fact point to considerably less warming, and one of them shows that the so-called transient response of climate to a trace-gas forcing, i.e, the way climate evolves as trace-gas concentrations slowly build up in the atmosphere, does indeed somewhat resemble the pattern observed in recent decades. Other calculations dramatically slow down the amount and rate of warming expected in coming decades. In- terestingly enough, it is of no consequence in those model calculations whether the IPCC "BaU" scenario is applied or the stringent-measures-scenario, which might have important policy implications (see Fig. 31). In any event, it seems as if a more realistic modelling of the oceans may go a long way toward explaining the discrepancies between the observed temperature trend and the one modelled thus far. Unfortunately, other models of the same type show completely different warming patterns (see Fig. 20). It is clear to all modelers in any case that a lot of work remains to be done - and could be done in the near future - to more realistically model the role of the oceans in climate.

2. The clouds The same can certainly also be said when considering the im-

pact of modeling clouds in climate model forcasts. Here, climate modelers have to cope with a variety of factors which can either increase or decrease cloudiness, change cloud physical properties and cloud type, which, in turn, can lead either to a decrease or increase in global temperatures in response to a trace-gas increase. Why clouds are cloudy business indeed is shown by an estimate that an error of about 2 percent in model-predicted cloud cover may cause an error in temperature as large as the envisioned

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greenhouse related temperature increase itself, thereby either cancelling it out entirely or enhancing it by a factor of two. The picture turns even bleaker when we consider how large an impact the type of cloud cover has on modeled climate change: Low clouds tend to counteract the greenhouse effect and high clouds tend to enhance it. But when we take account of the seasons and geographical locations involved, even that is not true anymore.

The very simplest example to illustrate this is the observation that it does not become as cold during a cloudy winter night as it does during a clear one; therefore, clouds, particularly low clouds, act as a blanket; whereas on a summer day, it does not become nearly as warm when it is cloudy as when it is sunny. Thus, clouds have a shielding effect.

Which of those effects will prevail on a global average, let alone on a regional level in a scenario of increasing trace gases, must be considered an open question, even though most of the models favor the enhancing effect at present.

This is due to the fact that they perceive the shielding effect of current cloudiness to prevail over the blanketing effect on a global average. They model a decrease in global cloudiness as a result of a trace-gas increase, leading to more solar radiation reaching the earth's surface, thereby adding to the warming.

There have been attempts to clarify the role of cloudiness by means of satellite observations, which, unlike observations from traditional weather stations, provide global coverage, particularly badly needed over the vast expanse of the oceans. The prelimi- nary results indicate that large regional differences exist regarding the impact of clouds on climate.

Whereas in the tropics, the shielding and blanketing effects of cloudiness very nearly cancel each other out, in mid-latitudes, particularly over the oceans, increasing cloudiness would cause general cooling and in high latitudes, an increase in cloudiness will lead to a warming. In the subtropics, there are some areas where an increase of high cloudiness would also cause a warming. This, however, only addresses the question of how clouds impact on climate once they are there, but not the question which concerns us, i.e., how clouds behave in response to rising trace-gas levels and the envisioned increased temperature levels. One factor which has hardly been considered in the GCMs is the way cloud- physical properties behave in a generally warming climate.

Some experimental and theoretical results indicate that low and middle-high clouds become optically thicker as they warm under


a trace-gas induced warming, therefore increasing the shielding effect and counteracting the trace-gas induced warming. On the other hand, some scientists claim that on balance, high clouds will be most affected, leading to an overall warming contribution of clouds in a warming scenario.

However, the latest news on this is that the inclusion of those cloud-physical processes may indeed slash the hitherto envisioned warming in half - even when considering the high clouds. It may in fact turn out that cloud physical processes alone are quite important and may also go a long way explaining why the model predictions have so far been unrealistically high.

Other researchers note the importance of deep cumulus con- vection - especially in the tropics - to the response of the climate system to increasing trace-gases. They point out that, depending on the modeling scheme employed, global warming may easily be slashed in half. In the tropics, big cirrus cloud shields generated by towering cumulunimbus clouds may act as a thermostat by cutting off the flow of solar radiation to the earth's surface.

A further point of interest which may be recalled here is that mid-latitude oceans in the Northern Hemisphere have been cooling over the past 30 years. It may not be too speculative to think that increasing cloudiness may have something to do with that. If that is the case, then how this might be related to the greenhouse effect is a totally different question; but, as we saw on page 90, cooling of mid-latitude oceans and the concomitant warming at low latitudes has led to an increase of the equator to pole temperature contrast and to an intensification of the storm systems which produce more clouds - and more cooling, thereby inten- sifying the temperature contrast between mid- and low-latitudes. This is a perfect example of a positive feedback loop and of a chicken and egg problem: no one knows which came first. Was it mid-latitude cooling or low-latitude warming which kicked in the sequence of stronger storms - more cloudiness - cooler temperatures. It certainly works both ways.

Even sulfur dioxide emissions may have been a factor in causing increasing cloudiness and cooling over the oceans. Scientists have discovered that increasing atmospheric SO2 levels provide increasing condensation nuclei on which cloud droplets may form. This may have been particularly prevalent downwind from continental areas of SO2 emissions in North America and Asia - right over the oceans.

To make a long story short, clouds only add to the general co-

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nundrum in which climate modeling finds itself: Here, as with the oceans, we can only hope to find some clarity in coming years by substantially increased computing power.

But, as most recent model results show, it is indeed more than conceivable that the more realistic modeling of oceans and clouds leads to a substantial reduction of the temperature increases modeled thus far, which would then provide at least a partial and sensible explanation - rather than speculatively hedging on a "natural cooling", which hid the greenhouse signal - for the divergent trends between modeled and observed temperatures during the last century.

We must therefore conclude that it is our foremost task at this time to concentrate all our efforts on climate modeling and to arrive at a more reliable and more dependable vision of what the future climate might be in the 21st century - taking into account all factors which may have a bearing on climate and not just trace- gas increases alone. This is in fact a view widely held throughout the scientific community.

6.

A Changing Perspective

ith this in mind, let us now return to the question of "impacts" of a climatic change through man's addition of trace-gases to the atmosphere.

Skimming through the scientific literature, it is hard to believe the enormous number of studies, reports, books and so on about "impacts" of a changing climate on health, agriculture, fishing, sea-level, you name it, all assuming and none of them questioning the model-predicted temperature increase and the ensuing climatic change.

One hesitates for a moment and then asks if all the money spent on those studies is money well spent, since we have just seen how unsound it is to assume that this tremendous temperature rise will occur. We might wonder whether the money would not have been better spent on climate research and, more specifically, climate modeling, because this is the number one source of concern about climate changes and the number one source of uncertainty.

Since it is obvious to everyone by now that, if the projected temperature increase does not materialize, all the envisioned negative impacts will not occur either. There will not be an increase in the frequency and severity of droughts, sea levels will not rise, sea ice and glaciers will not melt, there will be no inundation of sea ports and coastal low lands, in fact, there will be no foundation whatsoever for all the concerns about climate and "the most serious threat to mankind".

But even if we assume, as we should, that there is some greenhouse warming, albeit significantly less than predicted by the models, the lessons we have learned from climate history are quite clear: A slight warming of up of, say, 2 or 3° F is not at all to be considered a serious threat to the climate. On the contrary, it has been equated to a "climate optimum" throughout climatic history, and it were the periods colder than today which were considered dang- erous and detrimental to nature and human endeavors.

A similar opinion was voiced, assuming even a warming as large as current GCM simulations expect, by the Soviet climatologist M. Budyko to a stunned audience at a climate conference in

W

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Hamburg, Germany in 1988. He asserted during the conference that the warmer climate of the future would be so much the better, because it would also be much more moist (and not just in Si- beria, as critics were quick to suggest); growing conditions for plants would also be greatly improved by the increasing level of carbon dioxide in the atmosphere. There would certainly be no reason to think that "detrimental climate changes" or even a "climate catastrophy" would occur. The audience, which had conven- ed to be harrangued about the menaces the greenhouse effect "would certainly bring upon us", reacted to Budyko as if the scientist had been "swearing in a church".

We do not wish to dwell on the condition of Mr. Budyko's soul. We only wish to point out that some difference of opinion does in fact exist on the greenhouse issue, contrary to the impression one might get from media accounts.

But quite clearly, according to everything we have found out so far, the point made by Budyko must be accepted, i.e., that a warmer climate is a better one, particularly if viewed in conjunction with a increased level of atmospheric CO2. The FAO, the agricultural sub-organization of the United Nations, came to this conclusion at the Second World Climate Conference (SWCC) in Ge- neva in November 1990 - but was not very warmly welcomed.

It is easy to take issue with the contention that a warming of the magnitude expected by the models would still be "good", since a warming of that magnitude is untested by human experience and may indeed entail some adverse consequences, as we found out above; particularly, as many have suggested, because of the rate of climatic change which might occur.

But this is not the temperature level and rate of climatic change we can reasonably expect to result from an increase in the greenhouse effect alone; rather, as we have shown, we should probably expect a warming of the order of only 2°-3° F in the case of a CO2

doubling - which, judging from past experience, would still be in the "beneficial" range.

We are therefore facing the very odd situation that, as a result of our various industrial activities, we are not adversely changing our environment, we are benefitting it — a point made before when we were addressing the impact of a raised CO2 level on the biosphere alone. This is in fact the major issue which distinguis- hes the greenhouse debate from most other environmental issues such as air-pollution, acid rain, and the ozone depletion debate. In all those areas, we are dealing with proven adverse effects: air-


pollution does pose a health hazard; acid rain is detrimental, not only to vegetation but also to material surfaces; ozone depletion must be viewed as adverse, because an increased level of UV radiation is deleterious; the debate here is restricted to how dange- rous it is and whether the costs of combatting it are justified by the benefits of a cleaner environment. The public's answer clearly is yes to most of these questions. In the greenhouse debate, however, we are dealing with a situation where hundreds of billions of dollars are proposed to be spent worldwide to avert a change for the better. How sensible is that? How will those measures affect the average citizen if they are implemented? These are the questions we will take up later.

When the two factors are viewed in conjunction, i.e., an increased level of CO2 and a global temperature maybe 2° F higher than today's, our planet could easily be turned into a garden of Eden, and not, as many claim, or at least fear, into a disaster area. As before, when we were considering the CO2 increase alone, we have reached a philosophical, but not a scientific point: Shall we resist change just because it is a change, even if it is a change for the better?

Now, as we have established, even a temperature increase of 2° F due to the greenhouse effect in the next century might be very speculative, since we know with some confidence that a natural cooling, related to the quasi 200 year solar cycle may occur next century (see page 114). That would bring temperatures down from today's level by one or two degrees F or so. A greenhouse warming of 2° F may only balance that cooling, leading to temperatures 100 years from now which might not be very different from today's.

But we are still left within the realm of speculation and may at this point only be able to say, greenhouse effect or not, maybe it will be 2° warmer than today, but it may also be somewhat cooler if the solar induced cooling is greater than the greenhouse induced warming.

In any case, this perspective is vastly different from the catastrophic warming projected by climate models, and in all likelihood it renders a few truckloads worth of "impact" studies useless. This only underlines a point made at the beginning, i.e., that it is penny wise to spend a lot of money on developing climate models and pound foolish to spend much at all on "impact" studies of corrective measures. As anywhere else in life, it is always better to take step one first and step two second. Impact studies,

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especially regional impact studies which have been worked on fe- verishly, ought to be postponed until higher resolution, reliable model predictions become available.

A good case in point is a conference in late 1989 which concluded, after going through considerations similar to those we discussed earlier, that sea levels would only rise by about a foot or so instead of three feet as assumed before.

Studies like "The impact of a raised sea-level on Ocean City, Md." or "The impact of the greenhouse effect on water resources in Southern California" are absolutely nonsensical at this time, particularly if they are based on just one GCM forecast, because completely different results may very easily be obtained in those regional scale studies by using a different GCM.

Taking Stock

We have now examined the scientific basis of the greenhouse effect in some detail; we have analyzed the reasons behind the temperature rise of the last 100 years, and we have addressed the question of whether we can really expect temperatures to rise the way current climate model projections envision them.

Our answer has been: No, we really cannot expect temperatures to rise the way climate models predict it, particularly if we take factors other than trace-gases into account, which also have a bearing on climate.

Now that we have concluded our scientific assessment, we will direct our attention to the public debate on the greenhouse effect.

If you have read this far - and once you have heard the rest of the story, Part I - the public debate appears in an entirely different light. You might ask yourself: What is going on here? Either this book is full of nonsense, or the author has not read the papers recently! Why, everyone knows about rising tides, scorching heat, and melting ice caps. No doubt about it, that seems to be greenhouse reality.

Some of the more "advanced" greenhouse thinkers do not want to be caught up in the more intricate scientific issues surrounding the greenhouse problem, i.e., do we already see the greenhouse, is the observed warming caused by the greenhouse in effect or not, how large will future global warming be etc.? They simply cir- cumnavigate those issues by declaring them irrelevant to the case. Instead they now build their case on the following two proposi- tions:


1. Climate models predict a large warming for the coming decades. 2.We cannot afford to doubt those predictions for any reason because if they are right, it will mean disaster for the world. We therefore have to take countervailing action now. The problem is therefore elevated from a mere scientific issue to a public policy issue. According to these greenhouse proponents, the world finds itself in the position an airline might be in when it receives a bomb threat: It might be a serious threat, but it might also be a crank caller. What do you do in this situation? Evacuate the airport and fall victim to a prank? Or do nothing? Let a bomb explode and masses of people die? Greenhouse proponents say: Evacuate the airport at all costs, no questions allowed - without considering the costs of overreaction, which in the airline example is justified.

Our investigation has cast serious doubt on the first proposition. But we must also doubt the second one, since a moderate warming of climate will not mean disaster, as an exploding bomb would, but rather an amelioration of climate. Therefore, the disaster proposition is an inappropriate one which cannot be used here. Even if it could, the question would then be how much countervailing action shall we take? Clearly, the greenhouse debate has permuted into a political issue leaving scientific criteria far behind.

Viva The Media

In any case, there is one lesson we had better learn quickly: What appears in the media is one thing; the scientific basis for it may be an entirely different matter.

The scientific account given here so far accurately reflects the way it is perceived by large segments of the scientific community, and it is certainly defensible point by point - as you can find out yourself by looking up the references.

But then how is it possible for there to be such incredible noise about the greenhouse effect: Conference after conference, newspaper story after newspaper story - it all must come from somewhere.

Yes, it does. Brace yourself for the rest of the story Part II. The scientific community is divided on the greenhouse issue. A vocal group of scientists seriously believes that there are going to be deleterious climatic changes because of the greenhouse effect, and

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they are quite active making their opinion known to Congress, and to the public.

However, it is more the bark of their opinion than the bite of scientific evidence that has the public's ear, because, as we have seen, their views can be refuted, which is why their opinion is not shared by large segments of the scientific community, which takes a more cautious stance, such as we have expressed it here. Still other members of the scientific community think - although very few dare to say so publicly - that even a warming as large as that predicted by the models is good for all of us, a position pointed out here to show the range of opinion within the scientific community.

Most of this debate remains hidden from the public view and the majority of scientists remain quiet. The stage then belongs to those who are sometimes called the "greenhouse alarmists".

And the media are always up for it: Sci-fi and horror stories are good box office, bad news is always better than good news, the audience loves it and it's not the media's task to inform the public, but to make money and secure a market share. So there is certainly no reason for the media not to push the greenhouse effect, because here they have a sure-fire winner for some time to come, and the worse the horror stories get, the better.

However, one day the party will be over; at the very latest, when demands are presented to the public to contain a greenhouse effect we have seen will not occur in the predicted manner; when demands which cut so deeply into the American way of life, into the prosperity Americans worked so hard to achieve are presented to combat in essence a figment of the imagination, then, at the very latest, the public will start asking questions in the same way we have asked them here. And scientists and politicians alike had better be prepared to answer them.

The Real Issues

Scientists have a right to be concerned. Concern of scientists has led us to ban CFCs from spray cans, get rid of DDT and install catalytic converters in our automobiles, all of which presumably turned our world into a better place to live. Do the demands to curtail trace-gas emissions in order to combat global warming turn our world into a better place?

The "concerned" scientists have said yes, and we will analyze this concern shortly.

THE REST OF THE STORY \ 35

Before we do this, we should realize - the rest of the story Part III - that links exist between the climate change issue and other apparently unrelated ones, which we will also examine in some detail. Those links have led to an unfortunate intermingling of other issues with the climate change debate. One of our goals will now be to re-separate the issues and to relegate them to their appropriate places.

We will start out by presenting and examining the demands advanced by some of the concerned scientists and by recent greenhouse conferences.

One of the more commonly cited recipes to combat greenhouse warming was presented at the Toronto conference on "The Chan- ging Atmosphere" in June of 1988, in the middle of the American drought - a propitious - time to come out with such demands:

Reduce global CO2 emissions by 20 per cent by 2005. Ultimately reduce CO2 emissions by 50 percent. Phase out CFCs by the year 2000. Since then, those demands have taken center stage in the inter-

national trace-gas reduction debate. Those numbers are widely accepted in international fora and have even been adopted as guidelines by some individual countries. But is that what it takes to save global climate?

Now, we must first of all remember that those demands were advanced - if there is any basis to them at all, and if they were not, as one observer put it, "plucked right out of thin air" - on the back of model forecasts which had us in for a 5-7° F temperature rise for a CO2 doubling - which we know by now cannot be quite true. They were made to avert the negative impacts thought to be caused by that temperature rise; rising sea-levels, droughts, and so on. But if the temperature rise does not occur, the negative impacts will not occur either, thereby nullifying the basis of those demands from the start.

More generally, as new scientific evidence emerges about the magnitude of an expected climate change, the impacts assessed change as well, and so do appropriate response strategies. The scientific evidence that became available between 1988 and 1991 points to less warming, less sea level rise than was thought before. Consequently, the impacts and the response strategies should change as well, in the direction of less stringent measures. This lesson seems to have been lost on the IPCC (Intergovernmental Panel on Climate Change) and the Second World Climate Confe- rence (SWCC), where the "Impact" and "Response" group chose

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to ignore the results of the climate change group in its assessment, leading one analyst to speak of "mind-sets" within the impact and response groups. However, who would now be surprised that the greenhouse debate has largely taken on a life of its own, or that any hint pointing toward less catastrophic climate changes is frowned upon by those who use it to push their particular agenda to save the world?

Take Out Insurance Against Coming Changes For The Better? Sure- Greenhouse activists have argued - caveats about the reality of global warming aside - that we are operating in a realm of uncertainty and that we have to take out some kind of insurance against possible adverse climate changes in case those model predictions turn out to be right after all, as unlikely as that might seem at this point. At first sight, they seem to have a good point, because after all, it is good practice to always count on the worst and be prepared for it. That is why you take out insurance - auto, life, home, health. You do not plan to cause an accident, get sick, have your home blown away by a tornado, but you want to be covered if any of those unforeseen, unpredictable, catastrophic events does occur. The insurance premium you pay - or the kind of coverage you take out - is assessed according to the damage that might occur and according to the probability that it might occur: The higher the possible damage and probability of occurrence, the higher the premium, which is why you can not apply this simple insurance concept to the climate change issue.

First of all, we are not dealing with "unforeseen, unpredictable events of a catastrophic nature" if climate indeed slowly evolves over decades in a way the models predict. It is a slow process visible to everyone, one which can be stopped at any time - with some lags - if one chooses to do so; it is not some disaster that can strike at any moment without prior notice as the insurance concept assumes. Second, and more important, we know by now that a warmer climate is a better one, most certainly during the early stages which we might observe during the next decades. There- fore, the most likely outcome of an ongoing trace-gas build-up is not a catastrophic event but a beneficial one. Taking out insurance and paying premiums against coming changes for the better seems to be the height of folly. Third, who is to decide what type of "coverage" we should take out if one really thought one had to


prepare against changes for the better? No one would be able to assess, in dollars and cents, the extent of the "damage". Luckily we know that there is not going to be any damage to prepare for at this time. But nonetheless, the debate in coming years will center exactly on the question of how much insurance we should take out in order to fend off global warming.

But now we come to an additional point of overriding importance. We begin intermingling climate change with other issues. The proposal to reduce CO2 emissions to ward off the greenhouse effect - from the start or in an insurance type of approach - not only means reducing the greenhouse effect, but also reducing energy use along with it, as we have seen on pages 30-36. Therefore, not only would a reduction in energy use, and in particular, fossil fuel use, potentially reduce the greenhouse effect, it would also mean several other things as well:

1. Taking it easy with our energy resources 2. Generally reducing air pollution due to fossil fuel burning 3. By saving fossil fuel in the ICs, making more of it available to

the LDCs, thereby reducing global income inequalities 4. Reducing dependence on potentially insecure foreign energy

supplies We now begin to realize that the climate change issue fits right

into a much larger agenda, one we are quite familiar with by now, at least since the first version of the "Club of Rome" predictions of limits to growth and the general "Save energy" agenda hammered into us since the first oil crisis in 1973, and the plans of some of the environmentalists, who are against anything that has to do with industrialization and the comfort provided by technological progress.

In other words, various groups have added the climate change issue to their agenda, partially because they are really concerned about climate, partially because it fits their purposes; in any case, it seems as if their ulterior motive is not concern about climate as such, but concern over a number of other issues, in which climate may conveniently be used as an attention-getter, like a propeller on a beanie.

These groups are obviously not very interested in questioning the scientific basis of the global warming/greenhouse hypothesis, because that would be self-defeating to advancing their ulterior goals, so in order to add weight to their demands, they make the whole matter look as bleak as possible, regardless of the scientific

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soundness. To be sure, those groups get the most publicity and they fit wonderfully into the only-bad-news-is-good-news world cherished so much by the media.

But let us be fair: Most of the goals advocated by those groups - some of which are listed above - are noble ones and are to be commended in their own right, but we should make absolutely clear that they must be viewed separately from the climate change issue; because if we do not, we run into the danger of mixing scientific issues with ideological and political ones, and only use science as an expedient to further those political or ideological goals.

This does not help science; nor, in the long run, does it help those political or ideological ideas, because a willful or careless neglect of the scientific basis of the greenhouse problem - just because it is expedient - will sooner or later backfire in their faces.

Undaunted by simple fact, let alone susceptible to reason, the modern politician has borrowed a page from the text of alchemy and learned to transmute the political dross of energy policy into the precious metal of concern for the environment. With the aid of the smoke and mirrors of the electronic media, the modern politician has telescoped an issue which is many, many legislative periods down the road onto the bottom line of his or her campaign contributors' list. To paraphrase a well-known advertisement for American Express: The Climate Card, Don't Campaign Without It!

But the climate card, as we have found, is overdrawn. Nonetheless, this is the world we live in. Let us therefore ex-

amine some of the proposals made to counter a trace-gas build up, and see if they will be sufficient to meet the 20 per cent reduction target presented above in the case of CO2. Whether they will be feaseable at all is still another question. We also have to realize that we are back in computer-model wonderland. In other words, we are talking about measures which might have to be taken if we really expect the climate to change the way current GCMs predict.

We will do this for the simple reason that these proposed strategies might have some benefits aside from combatting the greenhouse effect; they may therefore be desirable in their own right.

7.

The Unreal Solutions - Grappling With CO2

Let us first turn to CO2 and the energy side of the coin. Accor- ding to greenhouse reports and suggestions on how to deal with warming, one has the impression that the only greenhouse gas is CO2, and the only human activity responsible for its emission is fossil energy use. We know, of course, that this is not the case, but most strategies aimed at fighting the greenhouse effect naturally enough somehow center on our old acquaintance "saving energy". Consequently, but maybe surprisingly, most greenhouse "experts" are energy experts, and greenhouse conferences lately pay only minor tribute to climate and deal more with the question of how to scale down energy use or how to finance technology transfer to third world countries. The entire greenhouse business is presently in the hands of people who are as far removed from climate as imaginable. Actually, many of those people have been around for close to 20 years and are now coming out of the wood- works, basing their "save energy" sermon on the greenhouse effect for a change. The new 1991 report of the "Club of Rome" is a good case in point. However, let us be fair: Saving energy has obvious benefits aside from fighting the greenhouse effect which should clearly be recognized. The main ones are: 1. Reducing dependence on foreign and potentially insecure energy supplies. 2. A dollar saved on the energy bill is a dollar earned. 3. Limits on energy resources.

1. Reducing dependence on foreign energy The oil crises of the 70s have tought a very harsh lesson to the

ICs and forced them to reduce their dependence on insecure supplies of foreign energy. Since then, use of oil has again increased and prices have risen along with the increased use; and unfortunately, if present trends continue, we may ultimately increase our dependance on foreign oil to the point where we once again become vulnerable to the same supply shocks which battered us in

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the '70s. The geographical distribution of oil resources paints a very clear, but somewhat somber picture: almost all the world's oil is in the Middle East. And people may remember what happened to oil prices in the '70s when OPEC was in control: they certainly did not go down. Therefore, we draw a very simple conclusion: we must increase energy use efficiency to protect our national economical and security interests in the face of unfortunate future shifts in the geopolitical supply pattern of oil. Indeed, in the fall of 1990, sooner than anyone expected, Saddam Hussein demonstrated again how critically dependent Western economies are on Middle East oil. This experience alone should be a strong catalyst to lessen the West's dependence on insecure oil supplies from the Middle East.

2. A dollar saved on the energy bill is a dollar earned There are good reasons to save energy not only on a macro-eco-

nomic level but also on a personal economic level. Energy costs money. If you save energy, you also save money. And nobody likes to spend money if he does not have to. However, we have to spend money on energy, because we do not want to freeze in winter, and we do not want to swelter in summer. So, we heat and air- condition our homes to be comfortable. We would prefer to spend that money on something else, on something we would like to spend it on, instead of something we have to spend it on. There- fore, any possible way to reduce the energy bill is most welcome to us, because it puts money back into our hands - to be spent according to our wishes, not our needs. Hence, there is a strong in- centive to save energy, for the simple reason of saving money.

3. Limits of fossil fuel resources As we saw on page 36-40, there may be limits to the supply of

fossil fuels after all. It somehow creates an sad feeling to burn all the fossil fuels, which took nature millions of years to create, in the time span of a few hundred years. Furthermore, one quarter of the world's population uses three quarters of the total energy - at present rates. Questions are posed as to whether this is equitable. A relaxation of the pressure on our global resource-base for that reason alone would be a commendable endeavor, particularly when we realize that fossil fuels may be too precious to simply burn them - since they may be used more sensibly as a feed stock in the chemical industry, as they are in products from plastics to phar- maceuticals, all of it is derived from oil - but which could also be


derived from coal. But at present, there does not seem to be a viable alternative to fossil fuels in many areas, and unless we want to go back to a 17th century lifestyle, or spend half of our pay-check on so-called alternative energy, all we can do to lessen the pressure on the global resource base is to save energy.

Playing The Reducing Game

Let us now consider what could be done to reduce CO2 emissions from fossil fuel use.

First of all, let us recall from page 22 and Table 4 that fossil fuel related CO2 emissions make up approximately 50 per cent of the man-made greenhouse effect at present emission rates. The human activities which contribute to those 50 per cent, and are possible target areas for reduction measures, are identified in Table 4.

From that table, it is quite obvious that there is no panacea or a "prime target" for regulatory action; even closing down all transportation worldwide would only lead to a 13 per cent reduction of the greenhouse effect, considerably less than a complete phase out of CFCs. The same would be true for electricity generation from fossil fuels.

Go Nuke!

This ought to be remembered when claims emerge to switch to nuclear electricity generation as a means to fight the greenhouse effect. This is not to say nuclear energy can not make any contribution in reducing CO2 emissions and the greenhouse effect, only that it can not make a very significant contribution which can not be achieved in other, simpler and first of all cheaper ways, not to mention the present regulatory quagmire a shift to nuclear energy of that scale would entail. It might be remembered that at present nuclear energy provides only 5 per cent of the world's total energy needs.

In addition, not only might we run out of fossil fuels, but also out of nuclear fuels. As a matter of fact, the resource situation of nuclear fuels - uranium - looks considerably worse than for fossil fuels. At current rates of usage, without accounting for a massive shift to nuclear power generation, supplies will only last a few decades. Some countries have sought to remedy this situation by the development of a controversial breeder technology. It is therefore

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widely acknowledged that nuclear energy can either provide only temporary pain relief from the greenhouse headache. For more than that, a broad scale breeder technology would have to be adopted. Even nuclear experts hate to think about the costs this would entail - not to mention the proliferation potential of high grade nuclear fuel. To be sure, the greenhouse effect is not the best of all excuses to push nuclear power.

Burn Now, Pay Later

A somewhat more viable strategy to reduce fossil fuel CO2

emissions might be fuel switching, i.e., the shift from high carbon content fuel to low carbon content fuel. We may recall from Table 3 that the amount of carbon contained in natural gas per unit of energy is only 60 percent of that in coal and 75 percent of that in oil. Consequently, if one used gas instead of coal, there would be an immediate CO2 reduction of 40 percent. Therefore, fuel switching has taken a front seat in the CO2 reduction debate. Added advantages of using natural gas include low emissions of sulfur and other pollutants. Natural gas may be used to replace coal and oil in the power generating and home heating sectors, but also in industrial processes. Compared to a shift to nuclear power, relatively small capital investments would be needed to switch burners from coal or oil to gas. Hence, fuel switching might be the ideal solution to our real and perceived greenhouse problems, were it not for the limits in natural gas reserves. At present, natural gas reserves are supposed to last roughly 50 years. If we step up usage now, we may accordingly run out at a far earlier date, maybe after 20 or 30 years, just at the point in time when the greenhouse effect might begin to become a problem, assuming the doomsday predictions are right - leaving us empty-handed then. Because then, with nothing else left, we have to use higher carbon content fuels to meet the world's energy needs.

Furthermore, in some countries, security of supply problems argue against a too heavy reliance on natural gas, since they are not blessed enough to have command over large resources of gas and they have to be content with coal instead - if they have that.

Leakages from natural gas supply systems - although small - may enhance the greenhouse effect because of the much greater greenhouse power of unburnt natural gas, which is essentially methane. Those leakages might then argue, from a greenhouse perspective, against an over reliance on natural gas.


Renewable Energy: Welcome To Alice's Wonderland

The best way to fight the greenhouse effect - and solve the world's energy supply problems - is a shift of the world's energy base to so-called renewables or alternative energies: wind, solar, hydropower.

Of those three, hydropower is indeed a proven resource of electricity generation, and, where available, a widely used source of energy.

But the other two candidates, wind and solar, largely represent a pipe dream when it comes to large scale generation of power necessary to fullfill the world's energy needs. Why? Even though they are technologically possible, they are more expensive by a factor of five to ten than power generation by means of either a fossil or a nuclear power plant. Energy experts are therefore quite certain that in the foreseeable future, meaning the next decades, the role of renewables will remain quite small and restricted to a few, special applications. Nonetheless, research in those areas is being intensified, and who knows, maybe ten or 20 years from now, some smart scientist might come up with a way to manu- facture solar cells at a fraction of today's costs and, all of a sudden, our greenhouse and energy worries will be over once and for all. But as of now, the potential of "alternative fuels" can be summed up briefly: Technologically: Yes, in some respects. Economically: No, in almost all respects.

The Ugly T - Word

One option which should not be pursued - even though it is the darling of nearly the entire environmentalist and ecotopian league - is the tax option.

So what if Wall Street hates the ugly T - word, we hate it too. The ugly T - word is introduced by the ecotopian league as a virtual panacea to all of our environmental, greenhouse and limits to global resource problems. The story behind it goes something like this: We put a stiff tax on fossil fuel use, which discourages the use of fossil fuels (thereby reducing CO2 emissions, slowing down the use of our limited resources, reducing fossil fuel related air pollution - and, probably most importantly, generating revenue). Some of that revenue may then be used to develop energy saving technology, or help third world countries on their path to "sustaina-

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ble" development, which they're entitled to at the expense of the "bad" rich ICs, who "robbed" them of their resources in the first place. Sounds nice, doesn't it?

But as always, if something sounds too good to be true, it usually is.

First of all, the imposition of a consumption tax (which is what a tax on fossil fuel use would be) always exacerbates social inequalities, because it hits the poor harder than the well to do.

If you increase the money spent on fossil fuels by a fixed amount, as a percentage, the increase is higher in a small budget than a large one.

Furthermore, tax increases enacted to pay for a certain purpose have a long and consistent history of not being used for the intended purpose very long, but rather being thrown into the general revenue bag, which the government loves to use so inefficiently.

A good example for this is a tax which the Imperial German government chose to impose on Champagne in order finance the build-up of its Navy prior to WW I - and to no one's surprise, that tax is still being levied today, 70 years after the downfall of Im- perial Germany. Worse yet - as economists know - revenue transferred by means of a tax increase from the efficient (private) sector of the economy becomes inefficient in the hands of government bureaucrats, thereby reducing the overall strength of our national economy. However, the worst is yet to come: The tax will in all likelihood not even achieve the intended purpose of reducing fossil fuel use unless it is so rigorous that it causes economic disruption as severe or much worse than the oil crises of the 1970s did.

Trigger a recession or even depression to prevent a climate change for the better?

The reason why it probably will not work is that there is a considerable amount of what economists call inelasticity in fossil fuel use, in other words, the demand for fossil fuels is to some extent price-insensitive. Why is that?

It has to do with the fact that you use energy not because you want to but because you have to. Here is an example:

If there is a gasoline price hike, you can not decide to walk 10 miles to work or spend 5 hours on the public transportation network in order to save energy - or money; you will grudgingly pay the higher gasoline price and drive anyway, because, even if you have to pay more, driving is still the most efficient way to get around.

A similar argument can be made for home heating: If there is a


heating fuel price hike, you decide not to freeze or run around your home in a blanket; you pay the higher price for fuel instead.

In both cases, it is obvious that the poor suffer the most under such tax'em-to-death proposals, because they lack the financial muscle to either pay the higher price or make up for the additional money spent on fuel by reduced spending in other areas. To them, and to most of us, the need to use energy assumes a central role in life.

Consider an example where such a taxing strategy might work and why it might work:

If the price of such non-essential commodities such as sugar or coffee goes up, you might indeed decide to forego sugar or coffee for a while in order to dodge the price hike. You can do that, because sugar and coffee are not as essential to our lives as the use of energy.

Therefore, there is a much higher elasticity in the price-demand relationship of those non-essential commodities; and taxation, in other words steering demand through the price, will probably work.

But as far as the more essential use of fuel is concerned, your more likely reaction to higher prices will be to grudgingly pay them and to make up for the money thus lost by spending less in non-essential areas - such as travel, restaurants, reading material, luxury goods. Therefore, the additional money spent on energy will be subtracted from money spent in other sectors of the economy judged to be less essential, which may lead, or contribute, to an economic downturn such as the ones we have witnessed in the 1970s and early 1980s. But fossil fuel use and CO2 emissions will not be reduced in the process.

One good example why a "quasi tax hike" did not result in decreased consumption of energy comes from Germany again. Between 1973 and 1981, gasoline prices, as a result of two oil crises, went up two and a half fold, mimicking as stiff a tax increase as is imaginable.

Yet, and this must be a surprise to all ecologists and tax hike proponents, total gasoline consumption went up 30 percent and CO2 emissions with them, mostly as a result of an ever increasing number of automobiles.

But that is not all. One would have thought that at least specific gas consumption went down (gas milage increased), but no, it even went up slightly (gas milage decreased) (see Fig. 32).

Conventional wisdom has it that at least gas milage should

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have improved under the impact of so steep a gas price hike. But this did not happen either. Apparently, the response to higher gas prices has been to continue to drive - and to drive relatively large cars. The higher cost of driving must then have been compensa- ted for by reduced spending in other areas. Obviously, no CO2

emissions were reduced despite the dramatically higher prices. And to finally give the the tax fanatics something to think about,

let us look at the absolute gasoline price level in the US and in Ger- many. A gallon of gasoline in Germany goes for $2.40 and in the US for about $1.10. Out of those $2.40, total taxes amount to $1.60, substantially in excess of US taxes and even substantially in excess of what dyed-in-the-wool environmentalists are proposing in the US.

But now, fleet average gas milage in the US stands at 20 and in Germany at 23 mpg (see Fig. 33). In other words, despite the horrendous tax level in Germany, there is about the same efficiency there as in the US. More remarkably, efficiency in the US has increased by about 50 per cent between 1974 and 1988 - despite the drastically lower price level in the US (see Fig. 33). The new-car- fleet gas mileage moreover is quite comparable in both countries and stands at about 28 mpg. Do you still believe in higher taxes as a means to increase energy efficiency? There are better ways.

This exercise could be carried out for other sectors of the economy as well. Data from the manufacturing sector of the German economy do not show any convincing relationship between the energy price level and energy efficiency (see Fig. 34). In fact, the largest efficiency gains were achieved in the 1950s and 1960s when energy prices adjusted for inflation were falling. Even in percentage terms, the efficiency gains were not larger under the high energy prices of the '70s and '80s. However, there are notable differences from one country to an other, and in the US economy, significant improvements in energy efficiency did not set in until after the first oil crisis in 1973.

In any case, there are substantial pitfalls in an "energy must be more expensive to reflect its real costs" and the resulting tax'em- to-death approach, which must be known to the people advocating it; but apparently, the opinion "if it feels bad, do it" prevails as the leitmotif among those who are promulgating those strategies and one wonders if they really are designed to counter the greenhouse effect or more to fullfill some sadistic desire to inflict pain.

Moreover, the notion of "environmental costs of fossil fuel use"

Figure 32. Trends of gasoline prices and specific gasoline consumption in Ger- many since 1966 (adjusted for inflation). The figure plots fuel consumption of the passenger car fleet in Germany (Liters/100 km) and fuel prices (in constant 1980 DM per liter). 1.00 DM per liter corresponds to US$ 2.10 per US gallon (in 1980 US$). Source: The German Federal Ministry of Transport; BP, various years.

is increasingly contested by some scientists who - rightfully as we have seen - mark down the beneficial effects of an atmospheric CO2

increase on the other side of the book-keeping ledger. For those of you who are less sadistically inclined, there are in-

deed much better ways to counter the greenhouse effect than "if it ain't hurting, it ain't no good".

A final note on taxing strategies concerns using tax money levied in the ICs to supply it to the LDCs in order to further "sust- ainable development" or "environmentally compatible development" there.

As good as it sounds in theory, we are again talking inefficiency of scale.

Both the World Bank and the International Monetary Fund (IMF) have long stories to tell about the quagmire that opened up when they tried to straighten out the economies of some of the LDCs which have, for various reasons, been pushed to the brink, or into the state of virtual bankruptcy.

As almost every major American bank found out the hard way, a dollar plunked into the economy of an LDC, especially in Latin


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Figure 33. Trends of energy prices and energy efficiency within the manufacturing sector of the German economy between 1950 and 1988 in Kg of ce per 1000 DM of goods produced with crude oil prices in DM per ton at constant 1980 prices (adjusted for inflation). Source: Data after Vereinigung Industrielle Krafrwirtschaft, various years; BP, 1990.

Figure 34. Trends of enery efficiency of the transportation sector in the U.S.and the FRG since the mid I960's. Fuel efficiency of passenger car fleets in the US and in Germany show different impacts from pricing and regulatory policies. Source: After Annual Energy Review, 1989; German Federal Ministry of Transportation, various years.


America, was a dollar lost. Even if the ICs did supply funds to the LDCs by means of a

"World Climate Fund" or a similar instrument, it is virtually impossible to ensure that money invested there is used in the intended way and are not simply snapped up by the upper crust to increase their fleet of Rolls-Royces or hillside estates or simply make a round trip to the NY stock exchange - the general public going away empty handed - and worst of all, getting stuck with the bill when the day of debt re-payment arrives.

Considering the difficulties encountered solving the much more pressing basic economic problems of those countries, it is hard to imagine, but it may not be entirely impossible, that environmental concerns will be given such a high priority.

8.

The Real Solutions The Premier Candidate

Before we get into the CO2 and energy side of the coin, let us first take a quick look at the second most important greenhouse gas, the CFCs, of which the Toronto conference demanded a complete phase out because of their role in ozone destruction.

As we saw on page 27, a phase out of CFCs would not only be a measure against the greenhouse effect, but also against stratospheric ozone depletion, and may therefore not only be a prudent, but very cost-effective strategy as well, in view of the fact that CFCs contribute between 20 and 25 per cent to the greenhouse effect at present emission rates, comparable to the entire, worldwide contribution of fossil fuel use in transportation and residential heating.

It may be considerably easier and less disruptive of human activities to think of some ways to replace CFCs than to think of new ways to heat homes or propel automobiles.

Therefore, any sensible strategy to counter the greenhouse effect would, for reasons of cost effectiveness and in order to disrupt human activities as little as possible, first and foremost address the CFCs.

We recall, however, that this is already being done; at present, out of concern over the ozone layer, but with the side benefit of also warding off the greenhouse effect.

We already considered this in our conclusion that any possible future warming due to the greenhouse effect would not proceed as rapidly as has been thought; therefore, one key element in staving off the greenhouse effect has already been implemented - though some would like to see the CFC phase out much sooner. No- netheless, it appears as if the importance of the CFC phase-out in scaling down the greenhouse effect in coming decades has not yet fully permeated the minds of most greenhouse thinkers who continue to hammer on CO2 and energy use as the one and only greenhouse gas and greenhouse activity. They give their secret away too easily: the name of the game is not concern about climate, but concern about energy use.


Try Technology

Now that we have spent so much time showing how not to do it, let us now show how to do it.

It appears as if energy might be saved - and CO2 emissions avoided - much better by continuously advancing and implementing new technology designed to use less and less energy in any imaginable field of application, be it in the automotive sector by designing ever more energy efficient engines, in the residential sector, through more efficient burners and better home insulation, and likewise in industry and the utilities through advanced process technology

In the automotive sector, the US has taken a commendable lead by requiring, as early as the 1970s, the auto industry to continuously increase gas milage; and the auto industry has shown that it can do that and increase profitability at the same time.

The way to achieve a reduction in energy consumption - and CO2 emissions - is mandating energy efficiency improvements by law in a way similar to how it has been done in the US auto industry through the CAFE (Corporate Average Fuel Efficiency) scheme (see also Fig. 33). To repeat, the industry has been able to significantly increase fleet average gas milage over the past 10-15 years and has increased profitability at the same time - and gas prices have fallen at least since 1981. It looks as if everybody came out a winner, and nobody was hurt, least of all the consumer. It ought to be possible then to set energy efficiency standards - according to what is technologically possible and economically sensible - on, say, home insulation standards, furnaces, utility and industrial burners and automobile engines.

It bears repeating that those measures should be taken not to avert a climate catastrophe, because, as we have seen, no such risk of any significance exists, but for reasons completely unrelated: common sensical and economical ones.

Indeed, we may expect that some of these efficiency improvements will be implemented in various sectors of the economy. The assumption that they will be has already been incorporated in our future CO2 scenario (pages 31-37) which led us to tentatively conclude that CO2 emissions in the ICs would remain roughly stable despite an ongoing, moderate economic growth. The additional factor we had identified, next to efficiency improvements, was structural change in the economy.

We have implicitly assumed, very importantly, that the effi-

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ciency improvements would be possible without causing "harm" to the economy, that is, the costs of energy saving investments would not be greater than the energy savings themselves, thereby rendering them economically sensible. They are therefore cost- neutral or "cost negative", i.e. they save costs. We should realize though, and maybe some of the greenhouse activists ought to as well, that we have been embarked on a course of continuously im- proving energy efficiency ever since the first oil crisis in 1973. In the ICs, there may be some areas where the potential for energy savings has already been exhausted or can only be reached when making excessively large investments - investments that will never be recouped by the energy saved. In that case, we would be doing harm to the economy because the costs of energy saving investments would be greater than the energy savings themselves, as well as the "harm" to climate, if that could be quantified somehow.

However, as we have seen, we can discount the "harm" to climate, because a slight warming, which is all we can reasonably expect in the next decades is beneficial, if anything; so we may concentrate, for the time being, on the energy savings alone.

If we now tried to achieve the 20 per cent reduction target by the year 2005 in the ICs - which we have dismissed on the basis that we do not expect a climate change significant enough to ren- der this reduction necessary, but keep it just for the sake of argument - we would probably have to rebuff it again on a second count, namely that we - nobody can be precise about that - would in all likelihood be harming our economy tremendously by requiring a pace in energy efficiency increase that would cost us more than the energy saved.

We recall that we were able to keep CO2 emissions constant only in the wake - and at the cost - of two major recessions and the ensuing high social burden on society. We also recall that crude oil prices (in inflation adjusted dollars) approximately quadrupled between 1973 and 1981 and that this quadrupling only led to zero growth of CO2 emissions but not to an actual reduction. Restruct- uring the economy to achieve a 20 per cent reduction of CO2

emissions and energy use over a relatively short time, notably through the pricing of energy, would in all likelihood wreak havoc on the economy.

This would particularly be true when applied to the 50 per cent reduction demands voiced by some for the subsequent decades, which at this time appears outright quixotic: it requires either an


unforeseeable technological revolution or a change of lifestyle back to the way of the Colonial New England. Maybe this is what some enviros are dreaming of.

Obviously, both of these reduction targets would certainly di- vert funds from other, more productive areas of the economy, and lower our living standards.

We therefore come back to a suspicion voiced at the very beginning of this chapter: Meeting those proposed reduction targets would undermine our prosperity and deeply alter our way of life - for no reason at all, because the justification given for those demands, an impending adverse climate change, is null and void.

But it should also be remembered that even if we had to expect adverse climate changes, the rationale given for those specific reduction targets is marginal at best and could not even be justified by an insurance type of approach; in fact it is basically non-ex- istent, which has led some observers to suspect that the Toronto figures were "plucked right out of the air". For one thing, we only have to recall from page 53, Fig. 8 that keeping CO2 emissions constant or at the rate of increase of 1 per cent would alone be sufficient to significantly slow the rate of atmospheric CO2 increase and push the doubling date for atmospheric CO2 far into the future. One only wishes that greenhouse conferences did their homework as conscientiously as they forge alliances with the major TV networks. But then again, the point is of course presenting the greenhouse effect in the direst terms possible.

In any case, energy savings and efficiency improvements indicated by economic considerations should be pursued as long as there is a net economic gain by doing so. This itself may provide quite significant reductions of CO2 emissions at no net costs and avoid punitive strategies by artificially raising the price of energy.

Clearly, even if we did expect deleterious climate changes, we would first of all have to exhaust all existing possibilities of reducing CO2 emissions by cost-neutral or even cost-saving measures before proposing strategies which would hurt everyone, be socially inequitable, and create a public furor - such as a dollar-a-gallon gasoline tax.

Additional strategies have been proposed to counter a CO2

build-up in the atmosphere, because energy savings alone would not achieve the proposed reduction targets. Some of those involve retaining CO2 at the source. Those strategies would be practicable only where CO2 is emitted in large quantities, as for instance in electricity generation and in large industrial burners. And indeed,

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a number of technological gizmos have been thought up to somehow get the CO2 out of the effluent, particularly of fossil fuel fired power plants. Most of these strategies would at least double the price of electricity, and in fact use more energy, leading to a more rapid exhaustion of worldwide fossil fuel reserves and clearly vio- late our first rule, i.e., that the costs of averting a change should never be larger than the costs caused by the change itself. Clearly, the costs would never be recovered by the energy saved, and they would place a considerable burden on all of us. Those strategies would only be justified if one really had to count on severe, detrimental climate changes as a result of an ongoing trace-gas build- up.

Some of those schemes are quite bizarre and involve deep freezing CO2 into solid blocks and depositing it on the ocean floor, which is undersaturated with respect to CO2, or to direct effluent CO2 into the deep sea by means of pipelines. Serious consideration of those strategies does not appear to be warranted at this point. Recently, a different way to reduce the atmospheric CO2

burden has been proposed. It has to do with the oceanic biosphere. We learned on pages 49-51 that the oceanic biosphere might represent a sink for atmospheric CO2, but that too little was known about its possible magnitude. Ocean biologists found out that algae, which use CO2 which enters the ocean from the atmosphere, grow much better when iron is supplied as a nutrient. In fact, some scientists suggest that relatively small amounts of iron would be sufficient to drastically reduce the atmosphere's CO2 load via enhanced algae growth. As one proponent put it: "You give me half a tanker full of iron, and I'll give you another ice age." Algae form the basis of the ocean's food chain and enhanced algae growth may in fact lead to a growth stimulus for the entire marine biosphere. Time will tell how realistic those proposals are and whether they really present a feaseable option to counter an atmospheric CO2 build-up.

So far we have only been concerned with the ICs and have concluded that even here, the demanded 20 per cent reduction is too much of a good thing; but when it comes to the LDCs, the real quagmire and hopelessness of the 20 per cent reduction target opens up.

As we have seen on page 31, given the moderate assumptions of a 2 per cent population and a 3 per cent economic growth rate and a moderate energy efficiency increase, CO2 emissions would grow at 2 per cent there - and would still grow globally even if the


ICs were to achieve a 20 per cent reduction. Realizing that, greenhouse activists have concluded that the ICs

would have to reduce their CO2 emissions not just by 20 per cent, but by an additional amount to make up for the additional emissions expected from the LDCs.

In view of what we have just said regarding the 20 per cent reduction target in the ICs, no further comment is offered on those even larger reduction demands.

This point becomes even clearer when one considers it a worldwide social issue to reduce global income inequalities, which will not reasonably be achieved by making the rich countries poorer, but by making the poor countries richer - through robust economic growth in the poor countries. Limiting CO2 emissions is the last of their concerns; they must instead be helped to grow their way out of their misery, even at the price of increasing CO2 emissions.

At any rate, if we take the very different concerns and positions of the LDCs into account, it is quite hard to see how anyone can reasonably expect to be meeting a global 20 per cent reduction target by the year 2005. Just remember that CO2 emissions due to fossil fuel burning have increased by 20 per cent between the end of the last recession in the early '80s and the late 1980s alone.

We realize at this point that CO2 emissions, along with a host of other environmental problems, are most directly related to the population increase we have experienced and probably will continue to experience. Can we condemn the LDCs for doing something that all developed countries have done as well through the centuries, namely clearing forests and destroying natural habitat for the sake of economic development? How important is it to save a piece of natural habitat, if you can escape dying of hunger by destroying it?

Already the attempt by international agencies to declare forest areas off limits to development have led to protest in Malaysia where the issue is not whether or not to use the natural resource, but whether the Malaysians will be compelled to export it as un- finished raw lumber or as semi-finished products such as plywood. From that standpoint the enviros are serving neither the environment nor the Malaysians but the system of debt repayment that condemns LDC's to a perpetual status as raw materials exporter. And in that way the contradiction is no longer between population growth and developement compatible with maintaining and replenishing the environment, but between the system of

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debt repayment (and the enviros) and developement compatible with maintaining and replenishing the environment, and population growth.

If Malaysia is an example too far away from home take the spot- ted owl controversy in California. With the stroke of a green pen, thousands of acres of public land were declared off limits to log- ging, thereby depriving hundreds of small and medium sized lumber companies of a livelihood. And thereby depriving one particular forest-products company with thousands of privately held acres of forest exempt from the stroke of the green pen, of effective competition. Perhaps the problems of the LDC's are not so very different from those facing many small and medium sized buisnesses in the IC's.

2. Let The Trees Grow

Let us now return to the question of reducing CO2 emissions — or an atmospheric CO2 buildup. As we have shown, economically sensible energy saving measures provide the currently best form of reducing fossil fuel CO2 emissions - or at least limiting their increase while also being beneficial to the economy as well as our personal finances.

Let us first of all highlight the contribution an end to deforestation in the tropics might make in global CO2 reduction strategies as we move into the second major field of possible options to slow down an atmospheric CO2 increase.

A look at the bare CO2 emission figures tells us that "land use changes" do account for about an extra 30 per cent of CO2 emissions on top of the ones related to fossil fuel use. Clearly then, an end to deforestation directly translates into a 25 per cent cut in total emissions. Ending deforestation is therefore desirable not only to preserve nature, but may also make a very significant contribution to slow a CO2 increase. It appears then as if "preservation of nature" in those regions where it currently is being destroyed should be high on any agenda that attempts to fight the greenhouse effect - and not only there.

We now consider the second major option to reduce or at least slow down an atmospheric CO2 increase. It is clean, cheap and efficient: Using the CO2 contained in the atmosphere to rebuild our natural biosphere.

Back on page 47 we went into a detailed explanation of how central a role CO2 assumes in our life and in the carbon cycle: The


CO2 we breathe out - or which comes out of a smokestack - is incorporated by plants in flower beds, and by the twigs, stems and branches of trees. Our entire biosphere depends and thrives on CO2 in the atmosphere. It is only a logical conclusion to enlarge the biosphere so that it is able to take up some of the excess CO2.

The option to counter or to slow an atmospheric CO2 increase by means of an expanded biosphere would have so many advantages that it almost appears mandatory to go ahead with it.

Currently, the biosphere is a net source of CO2, mainly because of land use practices in the LDCs. On the other hand it has been suggested that the biosphere has become a net sink again in mid- latitudes in recent decades, a conclusion which seems almost certain over parts of eastern North America. Obviously, the potential exists, but how can it be put to work?

It has been estimated that old mature forest stands are in virtual equilibrium with their atmospheric environment, that is, while some trees grow anew, taking up increasing amounts of CO2, other trees, old ones, die down while the carbon contained in their stems and branches is gradually released.

Scientists have suggested that mature stands of forests be sel- ectively logged, i.e., to take older trees out and use the wood - carbon - commercially, e.g., in the production of furniture. That would take at least a few decades and thereby prevent the wood from rotting and escaping into the atmosphere as CO2.

New trees would then be able to grow in the place of the logged ones, growing rapidly and acting as a sink for CO2.

It would also be possible to reforest areas which have been cleared in earlier decades and centuries. Clearly, that strategy would require substantial amounts of real estate. Estimates have been made on the area required to act as a sink large enough to re- capture all of the CO2 released by fossil fuel burning. They vary, depending on the types of trees used and the climatic zone in which the re-planting takes place. In one case, assuming that only 50 per cent of the carbon released by fossil fuel burning is fixed to trees, the required real estate amounts to about 3 million square kilometers, about one third the size of the US. Reforestation on that scale might be unrealistic. Yet smaller scale options are not therefore to be shunned.

The "capture rates" for carbon of various types of trees in tons of carbon per hectare and year are shown in Table 10.

The highest growth potential per unit area does exist in the subtropics and tropics, and it may even be possible to reclaim areas

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thought to be lost to any agricultural or forestry use. According to one estimate, combining all reasonable ways to increase forest growth, one arrives at a potential of possibly 1- 2 Gt per year of carbon fixation to trees, about the rate at which carbon is currently thought to be released from the biosphere. However, the degree of uncertainty is quite substantial here, and it could well be that the biospheric capture potential for CO2 is much larger than thought so far. Estimates run up to 4 Gt of current carbon fixation to temperate and boreal forests - compared to 4 Gt of tropical release. This would once again make tropical forest destruction a major reduction target. If it ceased altogether, carbon fixation to temperate forests and regrowth in the tropics might be able to better balance the global carbon budget - not even counting the oceanic sink, which might in fact also be enlarged by iron fertilization of algae growth.

The potential role of the biosphere in reducing atmospheric CO2 levels would almost certainly make life tougher for those who are pressing ahead with economically disruptive trace-gas reduction strategies, because a more efficient slow down of an atmospheric CO2 build-up could be achieved by simply halting deforestation.

Therefore, even if re-greening of the earth might not be capable of capturing all of the CO2 released by fossil fuel burning and not swallowed by the oceans (about 2 Gt plus or minus some uncertainties), it could still re-cycle a substantial portion of it.

Reforestation may consequently assume a significant role in slowing an atmospheric CO2 increase even if it cannot halt it altogether.

Afforestation would be one of the cheapest, cleanest, and best ways to combat a rising CO2 level, by far outdistancing proposals of "freezing CO2 and depositing it on the ocean floor", which is economically counterproductive anyway. In addition, everybody could very easily participate in afforestation by simply planting trees in his own back yard. Not only would one be making a contribution to fighting a CO2 increase, but they also add to the beauty of one's home; trees are a beauty to behold. They also provide shade to one's home, cut air-conditioning bills in the summer, and they provide wind breaks, possibly also cutting heating bills in the winter. According to estimates, the shading effect of additional trees around homes could slash air-conditioning bills by several billion dollars nationwide each year.

We will now consider an added factor which makes the tree op-


Table 10: Forests as a potential sink for carbon dioxide (in t of carbon per ha and year).

Tropics ca. 61 in African Savannahs ca 8 t in tropical hardwoods

Subtropics ca. 6 t (Australia, Argentina, Mexico) up to 15 t in Eucalyptus plantations in Brazil; potential up to 25 t

Temperate zone 0.7 to 31 in the USA and Europe; potential in managed plantations 10 to 15 t ca. 3 t in temperate zones of China

Boreal zone 0.11 in the northern USSR

Source: After data from EPRI, 1989.

tion look even better. We know from (page 48-49) that the oceans would be capable of swallowing a substantial portion of the emitted CO2 if the emissions growth rate is relatively small. However, we must realize that once the CO2 is in the oceans, it is basically lost to any future use. Since we have now found out we can use CO2 to grow trees, which are themselves a resource, would it not be a waste to let the CO2 disappear in the oceans? Wouldn't it be better to consider atmospheric CO2 a resource instead of a waste product, and transform this resource into usable carbon - putting trees to work? If we made it available to the biosphere by growing trees, we make it available for future generations. In other words, if we grew enough trees so they can capture CO2 before it is ab- sorbed up by the oceans, not only would we be fighting a hypothetical greenhouse effect, but we would recover a waste product - CO2 - and use it to rebuild our stock of natural resources - essentially free of charge: Because for all practical purposes, trees grow by themselves. Furthermore, we would be beautifying our natural surroundings - reversing the trend of tearing up our land. Therefore, re-greening the earth is a formula for solving a plethora of problems all at once - and essentially free of charge: 1. Combating a hypothetical greenhouse effect 2. Using a waste product to rebuild our stock of natural resources

free of charge 3. Beautify our natural environment

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This would be a true, ecological, "environmentally compatible" solution to a possible greenhouse and/or global warming problem, and hence our method of choice to combat it. It would involve a perfect re-cycling of burnt fossil fuel carbon into new natural resources available to us in the future. We therefore propose not to retain unavoidable CO2 emissions at the source, nor to con- vert them into a different, but useless product, employing costly methods, but let them out into the environment so that nature, trees, can use them to grow - if we cannot save energy and avoid the emissions in the first place.

Re-greening the earth then is our number 2 strategy, next to saving energy in an economically sensible framework ("no-regret measures"), and it might even be the number 1 strategy in view of the many advantages associated with it, the main one being rebuilding our stock of natural resources.

The first one, saving energy, might require large initial investments, but it saves us money in the end, as long as the investment in energy saving equipment is less than the energy saved; the second one, reforestation, requires a relatively small initial investment, but might pay off tremendously by providing natural resources to our children and grand-children, while being a source of beauty for our own enjoyment.

Those two avenues would provide a solid, economical basis for future management of our natural resources, which not only saves us money in the end, but is also compatible with our natural environment; indeed, improves it and builds it up to a splen- dor not seen before.

In this context, the lowering of the atmospheric CO2 level free of charge and the attendant slashing of the greenhouse effect may only be viewed as somewhat of a side-benefit - if warming ever becomes a problem.

We therefore reject all "if it ain't hurting, it ain't no good" proposals of limiting or reducing the atmospheric CO2 level - because it can be done better in a socially equitable, money saving, environmentally compatible fashion, which does not work against nature but with it. But strangely enough, there are complaints from the greenhouse front about suggestions that the CO2 load can be lowered naturally and that increasing CO2 levels are beneficial to the biosphere on the grounds that any suggestions about positive effects of increasing CO2 would "send the wrong signal to policy makers". But those complaints unwittingly send the right signal about the true nature of the concerns of greenhouse activists: The


name of the game is not climate, it's living standards in the ICs and their attempts to change those life-styles.

We now conclude the section devoted to "CO2 reduction strategies" and focus our attention on the remaining major three greenhouse gases namely CH4, N2O and O3.

Drain Up The Rice Paddies?

Reducing methane emissions to avert a risk to climate presents even tougher problems than the ones we had to deal with so far: With CFC and CO2 emissions, we at least knew which human activities were responsible for the observed increase and what - at least in theory - could be done to curtail emissions. With methane, we face an intractable situation on several counts: 1. Sources and magnitudes of emissions are only vaguely known 2. No practicable methods are known to curtail emissions 3. Even a complete cessation of many methane emitting activities

would not be possible, since they are largely related to food production. From page 24 and Table 5 we know that the atmospheric con-

centration of methane is increasing at about 1 per cent per year; and most of that increase is probably due to increasing food production since CH4 is mainly given off by cattle herds and rice paddies. Coal mining, oil, and natural gas exploration and handling are only minor contributors (see Table 5).

Turning our attention first to food production, the only open road to substantially lower methane emissions from cattle herds is to decrease cattle population, i.e. to lower meat consumption, because meat production is what cattle are used for. Vegetarians might like it, but it may be hard to convince the public to skip steak next Sunday - to help avert a climate change for the better.

Similarly, a call for substantial reductions of CH4 emissions from rice paddies is also completely off the mark, because reductions could only be achieved by a reduction of rice growing areas and therefore of rice consumption - a mission impossible in the face of rapidly growing population in LDCs, many of which depend on rice in their diet, and which will then tend to increase rice growing areas instead of decreasing them. It may be possible to reduce methane emissions somewhat by reverting to fertilization practices different from those of today.

CH4 emissions from coal mining operations and natural gas exploration, handling and distribution each contribute approxima-

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tely 8-10 per cent each to average annual emissions (see Table 5). CH4 emissions from coal mining operations can be - and are -

partially used for energy generation: They are burned. In terms of the greenhouse problem, burning of CH4 has obvious benefits, because burning of one molecule of methane produces one molecule of CO2. Since one Kg of methane has the greenhouse power of 58 Kg of carbon dioxide, burning off CH4 would reduce the greenhouse effectiveness of methane to 1/58th of its original value.

In coal mining operations, there are certain technical and oper- ational limits to the use of methane which may restrict the amount of methane used - and not given off to the atmosphere - to roughly 20 per cent.

In other words, there may be some, but not very much merit in using methane emitted from coal mining operations. In any case, the more pertinent question would probably be whether it is economically viable to invest in some methane retaining technology, assuming it existed or could be developed, if the investment does not pay for itself, i.e., saving other types of energy by burning methane.

If this is not the case, we would clearly be violating our rule one again, namely that the costs of an investment should always be recovered by the energy saved.

A similar case can be made for natural gas: The costs to avert the leakages that currently occur may be so astronomical that they will never be recovered by the re-captured natural gas (=methane).

We must therefore conclude that methane probably is the most intractable of the greenhouse gases, and that the prospects to reduce future increases look fairly bleak. Like it or not, there does not seem to be much we can do about it at present. On a less lu- gubrious note however, we should always remember that we are talking about hypothetical options which we might have at our dis- posal should there be a dramatic warm up. But luckily, we know by now that this is very unlikely to happen, which is why we should not lose too much sleep over it. We should keep the rice paddies wet.

Greenhouse Dwarf N2O

N2O, at a presumed 6 per cent contribution to the greenhouse effect, is the smallest of our greenhouse candidates (except for the somewhat controversial ozone).


We know from chapter 2 that the main anthropogenic sources are nitrogen fertilization, fossil fuel burning and biomass burning. Clearly then, a reduction of either of those activities would reduce the anthropogenic contribution to an N2O increase.

In a food starved world, it does not appear very likely that there will be a reduction in the application of artificial fertilizer aimed at increasing agricultural production. Therefore, reducing the use of nitrogen fertilizer hampers the ability to supply increasing amounts of food to a ceaselessly growing world population, especially in the LDCs.

Biomass burning, a point repeatedly made, should be curtailed for a variety of reasons, of which the emission of N2O is the least important.

Finally, our remaining target is the emission of N2O from fossil fuel burning.

It may be possible to reduce these emissions through changes in burner technology, but here, as before, it must be assured that our number one rule, namely the cost-benefit ratio, is not violated. And that may well be an open question since the greenhouse contribution of those emissions are ever so small to seriously question the meaningfulness of major capital investments in a small field just to avert a climate change for the better.

Ozone

That brings us to the last and most quizzical greenhouse candidate, namely tropospheric ozone. We have already discussed the potential role of decreasing stratospheric ozone in the greenhouse debate and refer the reader back to page 27.

Increasing levels of tropospheric ozone may increase the greenhouse effect, but we must view claims that it will increase by 50 per cent over the next few decades as a result of human activities with caution (see also page 42).

Ozone has not increased over some regions of the Northern He- misphere in the last 10-15 years - at least not in layers close to earth's surface. Those observations, and modeling results which put the ozone increase over the next 30-50 years at only 10 to 20 per cent, have resulted in our reluctance to assign a greenhouse contribution at current - or past - rates of increase to ozone. In any event, let's take a look at what could be done in theory to reduce the tropospheric ozone load.

Since ozone is not directly emitted into the atmosphere, but

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forms as a result of a complex chain of chemical reactions from so- called precursor emissions, our attention has to be directed to those precursor emissions. Those are mainly hydrocarbons, nitrogen oxides and carbon monoxide. The latter two compounds are emitted primarily from fossil fuel burning, while hydrocarbons are released into the atmosphere by a variety of other human activities as well. In addition, there is a sizable biospheric source of hydrocarbons which may be contributing to ozone formation.

In essence, however, it seems to be certain that curbing NOx

emissions offers one of the most promising routes to reduce or at least limit an ozone increase in the free and remote troposphere. NOX emissions have been one of the main targets in our past and present efforts to control air pollution on local and regional levels. The introduction of the catalytic converter in the mid-seventies was specifically aimed at reducing NOx emissions from automobiles, the major source category then and now. Most of the industrialized countries have followed suit since then and some have extended the NOx clean up to fossil fired power plants as well. This trend is likely to continue in the future - at least in the ICs.

Biomass burning in the LDCs is also thought to make notable contributions to ozone precursor emissions, and that is one more reason for it to be banned.

In any event, it appears likely at this point that some of the precursor reduction strategies will bear some fruit and limit future ozone increases in the free troposphere.

It may be pointed out in passing that those strategies which might work on a global level might not work at all on a regional and local level - and vice versa (see page 42), thanks to the complex chemistry of ozone formation.

We now conclude our section devoted to possible future trace- gas trends and options to reduce trace-gas emissions, or more generally, a trace-gas build-up.

All Nations Unite To Thwart The Big Greenhouse Menace?

We have now looked at theoretically and technologically feasa- ble options to reduce or limit a trace-gas build-up. But we have not looked at the prospects for implementing those options in the real world. This is our next task.

We should always remember that we were back in model-wonderland when we were considering strategies to slow down a


trace-gas build-up, in the case we thought that climate would really change the way climate models predict it. Now we have to realize that the prescribed measures would have to be taken in global concert if they were to succeed.

Why is that? Well, as we saw from Fig. 4, even the mighty US contributes only 23 per cent to global CO2 emissions, so that even if the US completely ceased to emit CO2 tomorrow, world wide emissions would soon continue to grow again, after a short recess, if the rest of the world were allowed to continue emitting CO2 at present rates of increase.

Therefore, if we really aim at reducing global trace-gas emissions we would have to devise a scheme according to which all nations, or at least the major trace-gas emitters, agreed to slow the trace-gas build-up in an equitable and, most importantly, verifiable manner.

While this may turn out to be possible with CFC emissions, (time will tell) all the problems encountered during the negotia- tion of a CFC agreement will be raised by a power of ten, at the least when it comes to agreeing on reducing or even slowing down CO2 emissions because fossil fuel use and CO2 emissions are interwoven with the very fabric of not just the industrialized societies but of every society on this planet, and any attempt to somehow reduce them will tear asunder the warp and the woof of human life itself.

We have encouraged the reduction of fossil fuel use because of the obvious macroeconomic and personal economic benefits within economically sensible bounds - not to mention the favorable aspects of reducing the pressure on our global resource base. Consequently, those measures should be taken in accordance with the economic guidelines laid down above.

But calls ring out for drastic reduction measures which go far beyond those which are economically sensible, and require either implementation of technologies whose costs will never be recovered by the energy saved, or drastic reductions in fossil fuel use, both resulting in a substantial lowering of our living standards.

How realistic is it to demand that nations agree to lower their standards of living, or to reduce fossil fuel use beyond the point which is economically justifiable, only to thwart a climate change we know will not occur? Which, even if it did occur, would be an improvement in climate for all practical purposes. For, as we have learned, periods somewhat warmer than today are called climate optima and not periods of adverse climatic conditions.

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This is the backdrop against which we have to examine the stance individual countries might take about reducing their ex- posure to fossil fuel use.

In any event, the trend towards restraining - if not reducing - CO2 emissions already is in full swing. Hardly a week goes by without a new country bowing to environmentalist's pressure and jumping on the band-wagon. Most countries joining the club have agreed to a stabilization at present levels until the year 2000 or 2005 instead of to a right-out reduction. This, however, could be achievable within a frame-work of no-regret measures and could even entail a net economic gain. It therefore reflects our view presented in the second chapter, where we laid out possible future CO2 emission scenarios, and where we concluded that in the ICs, CO2 emissions would remain roughly stable at present levels over the next decades. We concluded that this could be achieved through the continuous application of new, energy efficient technology. It more or less means continuing along a path we have been on since the first oil crisis in 1973. It is therefore understandable that those countries which made stabilization commitments did not have too many qualms doing it. Only those countries which committed themselves to a more or less drastic reduction may be in for a rough ride, and it remains to be seen whether they are going to stick with it. Especially when they realize that they are ruining their economy to fend-off global warming - even if warming is good for them - and that global CO2 emissions are re- lentlessly increasing, no matter what they do on a national level. Furthermore, the impact of those reduction efforts on the amount of expected warming is quite small. This point is illustrated in Fig. 35 and also in Fig. 31.

There are a number of countries whose present, and particularly future, economic well being depends to a large extent on their reliance upon domestic fossil fuel resources which are a cor- nerstone of their economic power.

As a matter of fact, the three largest CO2 emitters, which make up over 50 per cent of worldwide fossil fuel emissions, fall into that category. They are the US, the former USSR and the PRC (see Chapter 1, Fig. 4). All of those countries have extensive resources of fossil fuels and energy experts are quite sure that at least the former USSR and the PRC will make extensive use of them to further economic development. It may therefore be exceedingly difficult to convince them to drastically reduce fossil fuel use, even if one expected the detrimental climate changes the computer mod-


els predict, let alone the more realistic view presented here. Assuming there was some way to enforce global implementa-

tion, which at this point appears somewhat questionable, the western ICs are technologically and financially in a much better position to implement them than the former USSR and China, not to mention the LDCs.

Any international debate about "restricting fossil fuel use" will become a war of each against all of the countries involved, either with respect to their degree of dependence on fossil fuels, their technological and financial ability to implement energy saving technology, or simply with respect to their level of economic development. Some countries will have to use more fossil fuel in the future than in the past to further their economic development - to which they are as entitled as any of the developed countries before them. The most pressing problems are supplying their population with sufficient amounts of energy at the lowest possible cost.

One of those countries is China. The PRC will probably defy any calls to reduce the use of fossil fuel, simply because its main concern is to hurry along economic growth; it does not have any resources to squander, either technologically or financially, on state of the art environmental technology imported from the West, let alone developing it domestically. Laying emphasis both on increasing energy production and energy conservation is seen as a means to meet the country's energy needs. China's main energy source is coal. The country is very richly endowed with coal - and it will make use of it. Over the past 40 years China's coal production grew by a staggering rate of close to nine per cent per year, and presently stands at over one billion tons. Even if that growth rate was slashed in half over the next 15 years, China's coal production would still double, sending up worldwide CO2 emissions by 12 per cent from 1990 levels. So much for the Toronto demands.

China's main concern is to supply sufficient energy to a relent- lessly growing population. To economize on energy consumption is a means for the Chinese to provide more energy to more people. A possible climate change may not be very high on their list of concerns.

The same goes for the former USSR. Any future economic development, sorely needed, will be heavily dependent on the domestic resource base of fossil fuels. Energy experts from the republics quite openly admit that they cannot at all follow western concerns about the greenhouse effect. It may not be too unrealistic

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Figure 35 A: Impact of C02 reduction measures announced in some OECD countries on the modeled temperature trend in coming decades. Source: After Global Environmental Change Report, 1990.

to assume that the former USSR will put its main emphasis on economic development and only in the second place on environmental compatibility, although the environment in general is gaining ground in Moscow and in other republics as it already has in the former East Germany. Like China, the first concern is with providing sufficient energy. Advancing technology is seen as a means to increase energy efficiency needed to meet growing energy re- quirements in the face of a growing world population. The greenhouse effect is not seen as a problem. As far as climate is concerned, it is fair to assume that the USSR would only stand to gain from a global warming, even if it were as large as climate models expect, a view openly expressed by M. Budyko, and in all likelihood shared in leading circles not just of the former USSR, but of other East European countries as well. In the wake of the political


changes in Eastern Europe, economizing on energy will be a way of cutting dependencies on foreign energy, which, from now on, has to be paid for in hard western currency. The economies are not yet strong enough to sustain a heavy reliance on western imports; but they eventually will be. Once living standards begin to rise in Eastern Europe, with everybody driving an automobile, owning a freezer and all the other indispensible household goods we are so used to, energy consumption in Eastern Europe will move in only one direction: up. Hard times ahead for greenhouse proponents.

In any case, the republics of the former USSR would act doubly against their own interests if they implemented costly strategies to slow or prevent a trace-gas build-up in the atmosphere.

A similar argument can be made for the US. The only fossil fuel base left to the US, after supplies of oil and gas have run out in several decades time, will be coal; and it is hard to imagine that the US will renounce the use of the only major fossil fuel left to it-

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self on the basis of an imaginary climate change, which, if it occurs at all, will be mostly beneficial.

In short, as this brief review of the position of the three major CO2 emitters shows, the coming debate over possible climate changes and CO2 reduction strategies will be one of economic interests and preservation of national power, as well as the prosperity of nations and individuals vs. possible climate changes. Re- ductions of prosperity in the developed world (and delays in achieving higher prosperity in the lesser developed world) will be weighed against possible detrimental effects of a changing climate.

Of course, the irony, as we have found out, is that a mildly warming climate of, say, 2° F warmer than today must be viewed in the light of all the evidence available from climatic history, not as detrimental to nature and human activities, but as beneficial. It is almost tempting to conclude that we should not be thinking about averting such a change, but instead about how to hurry it along.

But even if we do not take an extreme position, we are pressed to ask whether it makes very much sense to fight such a climate change at a high cost to society, which is what a variety of pressure groups are advocating.

Furthermore, even if the democratic societies of the West, or any country by itself, decided to go ahead and reduces trace-gas emissions at whatever cost, differing economic interests in other parts of the world, removed from the control of western democracies could, and in all likelihood will, very easily make up for the trace- gas emissions saved here. This is exactly the way things are shap- ing up in the early 1990s: Some western ICs have committed themselves either to a stabilization or reduction of CO2 emissions while others, most of the LDCs, have said no, and their emissions will more than make up for the emissions saved in the ICs in the future, as they already have over the past 10-15 years.

Predictably, taxation of fossil fuel use is the main vehicle proposed to achieve a reduction in the ICs, because it is the easiest to implement administratively. As we have said before, this is fine to raise revenue, but completely inept to reduce CO2 emissions, unless the tax is so strangulating that it ruins the economy (see pages 145-151). Some countries have chosen to impose a "token" carbon tax, i.e., a tax which is smaller than the regular price swings of fossil fuels, and which has therefore an insignificant effect on fuel consumption, but has the double advantage of raising revenue and providing governments with an environmental fig leaf:


"Look, we have done something for the environment!" Strangely enough, this political expediency may nonetheless be the best way of getting rid of the problem in the least annoying and least harmful way: the public pays an extra dime on gas (half the Gulf War-induced gasoline sur-charge), the budget deficit is reduced, and the enviros can not scream as loudly any more. The only hitch, of course, is that CO2 emissions will not go down, but it will take a few years until people notice that, and then it will be up to the next president or congress, whoever can get the most mileage out of this low octane issue.

But if people decide to really slap a big tax on fossil fuel use, a potentially recessive or even depressive one, entire segments of industry might move a la NAFTA from "CO2 restrictive" countries to "CO2 lax" countries - taking with them jobs and economic growth. Again, the public would be the big loser, because lost growth and lost jobs will directly translate into reduced public prosperity, but not necessarily into lower profits for industry.

The big misunderstanding unfortunately peddled by enviros and greenhouse activists is the notion that industry wants to stall action on staving off global warming in order to protect profits at the expense of the environment. Well, think again. If taking action from the environmentalists' point of view means taxing the heck out of fossil fuel use - the bottom line of most of their strategies to fight global warming - who will be stuck with the bill? Your local utility, which generates electricity from coal? Or your gas company? Or Exxon? Take a wild guess: it's you, the average citizen and consumer. Because any tax on fossil fuels will simply be "roll- ed over" to the consumer: the proverbial man on the street gets stuck with the bill. Most of those measures do not cost the energy industry a penny, because any costs they incur will be reflected in the price of the product they sell, so why should they oppose measures to curb global warming and risk a stink in public with the enviros? This is the big danger in this debate. Any effective lob- bying by industry is essentially precluded. Industry is cautious by and large these days, and tends to assume a low profile concerning environmental issues in general. Instead, they begin to practice "Corporate environmentalism" image and make it a selling point. That is all right for them, because as long as the public buys it, they rake in a double gain: Being pro-enviro and making an extra profit. Even in this scenario the public gets the short end of the stick because it has to pay the higher price for a product, regardless of whether it results from a justified environmental con-

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cern or not. Not having a lobby or politicians to represent its interests, the public is a defenseless victim of manipulation by various interests of the biggest shell game ever pulled on it: The Green- house Threat. Be alerted to the dangers lying dead ahead. We know by now that the cure proposed by greenhouse activists is much worse than the hypothetical greenhouse ills.

Clearly, it is very hard to imagine that concern over climate, if it were really justified, prevails over economic interests - unless it becomes apparent to all that climate is changing and is changing for the worse.

Luckily, we know that this will not be the case, because, to run that point into the ground, a slightly warmer climate is a better climate. Finally, we should recall that even a slight warming expected from the greenhouse effect may not materialize within the next century after all, because of the countervailing effects of solar induced cooling, to which the greenhouse effect may be a desirable counterweight. And any attempt to ward off the greenhouse effect - under considerable economic sacrifices - would then really be harmful to us: Because this much is sure: A cooler climate is a worse climate.

Hence, by hastily enacting drastic reduction measures, we will be harming ourselves twofold: First, by diverting valuable economic resources to reduction strategies, and second, by promoting a cooling of climate that will be harmful for sure.

Consequently, to be on the safe side in all respects, it is wise at this point to adopt those measures which are not harmful either way, namely save energy to the extent that is economically sensible: the so-called no-regret measures. Further, promote research into all areas related to the greenhouse effect to clarify those uncertainties which need to be overcome to arrive at an understan- ding of climate which is scientifically sound and comprehensive enough to serve as a basis for decision makers.

A similar conclusion has been drawn recently by a Washington, D.C. think-tank which expressed a view widely held throughout large segments of the scientific community in the US. Those ideas also form the basis of the position which has been taken by the US at the SWCC in Geneva in November 1990 in an unlikely coalition with the USSR and several other countries - against an overwhelmingly pro-greenhouse international community, particularly in Western Europe. It remains to be seen whether, in the US, common sense continues to prevail over the ideologues. In Western Europe at least, they have hit in a few runs....

9.

Now You Know The Rest Of The Story....

We are now drawing closer to the end of our investigation of the greenhouse effect and the problem of global warming; a problem which has been widely misrepresented to the general public due to an unfortunate admixture of the science involved with partisan concerns of those scientists who attempt to promote those concerns, with the media and political pressure groups. We have attempted to separate the scientific issues surrounding the greenhouse problem from other issues, by and large unrelated to science.

In all our endeavors, we should base our decisions on how to deal with the greenhouse effect not on concerns, fears, beliefs, hopes, assumptions and expectations but rather on firm scientific ground. We should also recognize those who are trying to create fear and concern among the public in order to further their political or ideological goals. Let's call their bluff and act accordingly.

After all, we live at the edge of the 21st century and we've come a long way since the dark days of the Middle Ages when our lives were built around fears and atavistic beliefs. Our modern age is characterized hopefully more by logic and rational thinking and not so much by those fears - which some love to nourish, be it to further their ideological goals or to simply make money, as in the media's case.

Media 1, Science 0

In the current public debate about the greenhouse effect those fears have (deliberately?) been fanned by an alliance of "concerned" scientists, the media, special interest groups and politicians alike, all of whom stood to gain massively by doing so:

The "concerned" scientists finally got out of their boring lab jobs into the limelight of national attention; the media makes more money by printing horror stories; and it all fits nicely into the agenda of various special interest groups. Meanwhile, calls for action ring out, smart politicians swiftly realize they can earn easy

174 GLOBAL WARMING

votes by being "concerned" as well, and political careers are built around the global warming issue. Why, it would be downright discouraging for the careers of the people involved if the greenhouse effect proved to be anything less than catastrophic.

In this climate, it is difficult to arrive at a scientific assessment of the day of the week. Reports are drafted, research money allo- cated, and it all flows back to the beginning in a positive feedback loop in which everybody comes out a winner: The scientists get more research money, the media write better horror stories, the politicians get their votes, by "acting". The danger is quite high that this "acting" will be taxation of fossil fuel use, a mere pallia- tive in terms of slowing the greenhouse effect, particularly when it is imposed only in individual states and countries (see page 145- 154). But it will go down well with the enviros anyhow, and it may be used after all to cut the budget deficit. At any rate, nobody has the slightest interest in stopping this beautiful merry-go-round. Unfortunately, not even the scientists involved do: why should they kill the goose that lays golden eggs? As long as the fears are kept alive, the research money keeps flowing in. But they should be careful. If they carry their message too far, politicians will ask them: why more research money if we know for sure that global warming is coming? Clearly, what we need here is a more independent view of those environmental matters which are of great concern to society. But as of now, too many are gaining in too many ways to call a halt to the environmental porkbarrel.

This is not to say that the groups referred to are doing so out of malice; on the contrary, most are probably sincere; they just do not have any interest in halting it, because to them the benefits are greater if the debate built on fear and concern continues.

The time will have long since run out when, out of this cuckoo's nest of pseudo-science, media spectacle, ideology and politics, an attempt is made to formulate policy to cope with environmental problems - in defiance of real science. It were wise at this juncture that matters be taken out of the hands of special interest groups and returned to science to arrive at a sound assessment of the greenhouse/global warming issue which can provide a solid foundation on which men and women of good will may base their decisions.

So far, science, next to the public, which has been kept disin- formed, has been the only big loser in this debate. And every decision that an educated, democratic and enlightened society of the late 20th century takes should be based on a scientifically sound,


and defensible foundation, and not on "fears" and "concerns" whipped up by the media and special interest groups alone. Otherwise we would be throwing hundreds of years of scientific progress and culture right out the window and be moving back to the dark days of the Middle Ages. A strong case is made to to move science back into the greenhouse/global warming debate and ideology and special interests out.

We therefore arrive at the following greenhouse summary and greenhouse action plan (GAP).

Greenhouse Summary

• An increase in atmospheric trace-gas concentrations, partially if not largely related to the ceaselessly growing world population, leads to an increase in the greenhouse effect.

• An increased greenhouse effect - viewed in isolation - ler ds to an increase in global temperatures, the magnitude of which is unknown, but very likely considerably less than the 6-8°F forecast by current GCMs for a CO2 doubling. It may possibly be in the neighborhood of 2°F.

• When other, natural, factors are considered, pointing to a cooling next century, the expected greenhouse warming may be partially balanced out, leaving temperatures where they are today or only slightly higher.

• The timing of any greenhouse gas induced temperature increase depends on future trace-gas emission scenarios. Based on probable emission scenarios for CO2, the major greenhouse gas, the point of doubling current CO2 concentrations and the associated increase of radiative forcing will, not occur until late next century or later. When other greenhouse gases are considered, the warming will occur sooner.

• A warming in the neighborhood of 2° F, which might result from a CO2-doubling, must be considered largely beneficial for nature and human activities.

• An increase of atmospheric CO2 concentration must be considered beneficial for the biosphere.

• An increase of atmospheric CO2 in conjunction with slightly raised temperatures is even more beneficial for the biosphere.

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Close The Gap?

It is hard to press for a greenhouse action plan (GAP) after reading this greenhouse summary. There does not appear to be any need for taking action against coming changes for the better. But what if we are wrong, however slim the chances might be?

Let us do the things we should do anyway and which benefit us regardless of whether there is some greenhouse warming or not, and whether it is beneficial or not. We therefore pay our respects to the greenhouse advocates, but do not share their ulterior motivation in advocating the notion that the climate changes we are in for will be adverse. We have realized that there is no reason to fear climate changes in coming decades as a result of greenhouse warming and we do not have to resort to questionable methods to whip up public support to institute energy saving measures, because that seems to be the real motive behind fooling the public into believing that we are in for adverse climate changes. Let's call a spade a spade: it's a bluff.

We then propose the following greenhouse action plan (GAP):

The Greenhouse Action Plan (GAP)

• To resolve uncertainties associated with future climate changes, a sufficiently funded research program should be initiated to arrive at a scientifically tenable assessment of the global warming/greenhouse issue to provide a basis for decisions that go beyond the ones that will be outlined below.

• The social conditions and living standards in the third world must be improved such that population growth can proceed in a reasonable fashion, thereby lessening pressure on the environment and global raw materials.

• To protect our national economies and the global energy resource base only, those energy saving measures should be considered which are economically sensible.

• Taxes on fossil fuel use to reduce CO2 emissions are generally rejected.

• Biomass burning should be halted to preserve natural habitats and stop the process of species extinction which is proceeding at a rate unprecedented in earth's history.

• The biosphere should be used to re-capture atmospheric CO2


in order to rebuild the stock of natural resources by means of a global afforestation program.

• As an insurance policy against global warming, a reduction of CFC emissions provides the most cost effective means of combating the greenhouse effect.

You will notice that in this plan none of the points - other than the last - is specifically designed to counter a perceived threat to the climate - for the reasons you know by now. However, they do have the added benefit of reducing a trace-gas build-up in the atmosphere and thereby countering the greenhouse effect up to the point at which those measures can be implemented at no net cost; in other words, the economic benefits of energy saving measures or afforestation programs should be larger than the costs they incur.

And this is exactly where this plan differs from omnibus reduction demands, which were based on untenable model projections in the first place.

If we briefly review the points, we see the necessity to intensify climate research to develope a causal, physical explanation of what makes the climate system tick - considering all factors and not just trace-gases.

In the field of climate modeling, the primary task is an upgrading of existing computer modeling, for which increased number crunching power is sorely needed, plus a full-fledged attempt to better understand the underlying physics of the atmosphere.

Some experts feel that a research program over a 5 year period should be capable of producing tangible results that would provide a firmer footing for decision makers to rely on. That is a time frame we could certainly afford, in view of the fact that a warmer climate would be the better one, even if a warming occurred during those 5-10 years as large as current models predict. But we know by now that this is very unlikely. The costs of such a research program would be small compared to those incurred by needlessly embarking on a large scale trace-gas reduction scheme.

The option to achieve CO2 reductions by a tax should be rejected for the following reasons: • Social inequalities will be exacerbated • Harm will be done to the national economy by shifting funds

away from the efficient to the inefficient sector of the economy. • CO2 emissions will not be reduced in the end because of inelas-

ticities in the energy price-demand relationship.

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The real environmental disasters of our time are taking place in those areas where man destroys his natural surroundings on a scale unprecedented in history. This concerns particularly the forests which are being irrevocably destroyed by large scale use of slash and burn technique and mechanical methods.

Regardless of any CO2 contribution of biomass burning and a possible impact on the greenhouse effect, that destruction must stop.

In most questions that arise in connection with global warming it is clear that political and economic groups have become involved with this issue which have little or nothing to do with the matter at hand. One does not need to invoke the Greenhouse Effect in order to propose useful change. That goes for our suggestions which are useful in and of themselves, as well as being effective against a build-up of CO2 in the atmosphere. The public has a right to know why a bebate on climate has mushroomed into an international mania.

Time is running out on the greenhouse alarmists. If they cannot cast their proposals in legislative form, their bluff will be called sooner or later. At that point, science in the quest for truth will prevail against unfounded, pseudo-scientific assertions, and the personal and ideological convictions which sustain them.


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GERD WEBER was born in Braunschweig, Germany in 1952. He studied meteorology and climatology at the Free University of Berlin and Indiana University at Bloomington. He received his MS at the University of Michigan at Ann Arbor in meteorology and did his doctorate work at the Max Planck Institute for Aero- nom, receiving his PhD from the University of Berlin in 1985. Since then he has worked as a consultant and re- searcher at the Hard Coal Association in Essen, Ger- many. His interest in nature goes back to boyhood when he helped out on the family orchard, where he continues to assist in his spare time in the care of two hundred stately old apple trees.

gerd r. weber (1992) global warming - the rest of the story

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