Chapter 19

June 1991: Mount Pinatubo (Philippines) exploded

Airborne pollutants, deaths, and damage

Affected climate temperature

James Hansen(NASA) cooled the temp of the earth by )0.5* over a 19th month period. Then the earth would warm

The overwhelming scientific consensus is that the earth’s atmosphere is warming rapidly, mostly because of human activities, and that this will lead to significant climate change during this century.

Over the past 4.7 billion years the climate has been altered by◦Volcanic emissions◦Changes in solar input◦Movement of the continents◦Impacts by meteors

Over the past 900,000 years◦Glacial and interglacial periods

Over the past 10,000 years◦Interglacial period, fairly stable climate and

steady average global surface temperature Over the past 1,000 years

◦Temperature stable but began to rise during the last century when forests cleared, fossil fuel burned

Over the past 100 years◦Temperature changes mostly since 1975

Analysis of radioisotopes in rocks and fossils Plankton and radioisotopes in ocean

sediments Tiny bubbles of ancient air found in ice

cores from glaciers Temperature measurements taken at

different depths from bore holes drilled deep into the earth’s surface

Pollen from lake/bog bottoms Tree rings Historical records - 1861

Without the natural greenhouse effect, warms the earth’s lower atmosphere and surface.

Solar energy absorbed by the earth radiates into the atmosphere as infrared radiation(heat)

1% of earth’s lower atmosphere is compressed of greenhouse gases- water vapor, carbon dioxide, methane, and nitrous oxide◦Cold, uninhabitable earth

Since the Industrial Revolution (275 years ago)◦CO2, CH4, and N2O emissions higher◦Main sources: agriculture, deforestation, and

burning of fossil fuels

Correlation of rising CO2 and CH4 with rising global temperatures, during past 400,000 years

Countries with the largest CO2 emissions- US, China, EU-27 contries, Indonesia, Russia, Japan, India

Per capita emissions of CO2

Scientific and economic studies◦ 2007: Field and Marland

560 ppm by 2050 – 1390 by 2100Tipping point 450 ppm

◦ 2008: Aufhammer and Carson China’s CO2 emission growth may be underestimated

Ice core analysis – 60% of methane emissions ◦ human impact – landfills, raising live stock,

extracting fossil fuels◦Nitrous oxide – nitrogen fertilizers

Intergovernmental Panel on Climate Change (IPCC)◦ 90–99% likely that lower atmosphere is warming◦ 1906–2005: Ave. temp increased about 0.74˚C◦ 1970–2005: Annual greenhouse emissions up 70%◦ Past 50 years: Arctic temp rising almost twice as

fast as the rest of the earth◦ Melting of glaciers and floating sea ice◦ Prolonged droughts: increasing◦ Last 100 years: sea levels rose 10–20 cm

Al Gore and the IPCC : Nobel Peace Prize

Natural and human-influenced factors could have an effect on temperature changes

Drop in average cover of summer arctic ice

Mathematical models used for predictions

Global warming: rapid rate

Human factors are the major cause of temperature rise since 1950

Human factors will become a greater risk factor

Since 1975- satellite and balloon measurements ◦ Troposphere has warmed◦ Stratosphere has cooled

Scientists have concluded that the rapid rise in global mean temperature could not be the result of increased solar output

Solubility of CO2 in ocean water – removes 25-30% of the carbon dioxide pumped into the lower atmosphere by human activities. Some of it converted to insoluble carbonate salts that are buried in the bottom sediments

Warmer oceans ◦ Solubility decreases increases atmospheric CO2

◦ Coral reefs destroyed◦ Increased acidity –less carbon dioxide absorbed,

increases growth of some algae◦ drop in populations of phytoplankton,

Antarctica’s Southern Ocean and the North Atlantic Ocean –decrease in carbon dioxide uptake

Warmer temperatures create more clouds by increased evaporation of surface water◦ Thick, light-colored low altitude clouds: decrease

surface temperature◦ Thin, cirrus clouds at high altitudes: increase

surface temperature

Effect of jet contrails on climate temperature – they expand and turn into cirrus clouds that release heat into the upper troposphere

Aerosol and soot pollutants◦light colored sulfate particles, reflect

sunlight and cool atmosphere◦sulfate particles also cool the lower

atmosphere by forming condensation nuclei that form cooling clouds

The projected rapid change in the atmosphere's temperature during this century is very likely to◦ Increase drought and flooding, ◦ shift areas where food can be grown, ◦ raise sea levels, ◦ result in intense heat waves,◦ cause the premature extinction of many species.

Very rapid, global change in climate – projected rapid increase in average temperature in the lower atmosphere

Worst-case scenarios◦ Ecosystems collapsing◦ Low-lying cities flooded◦ Wildfires in forests◦ Prolonged droughts: grasslands become dust bowls◦ More destructive storms◦ Glaciers shrinking; rivers drying up

Fig. 19-7, p. 507

Stepped Art

less moisture in the soil – NPP will decrease stream flows and available water will decline Biodiversity will decrease growth of plants/trees will slow forest and grassland fires will increase some lakes/seas will shrink and disappear,

rivers will fail to reach the sea 1-3 billion people will face water shortage dry climate biomes will increase – savannas,

chapparal,deserts

global warming be worse in the polar regions – exposure of darker land, absorb more solar radiation

floating sea ice disappearing – could affect the average rate of precipitation in certain areas

Mountain glaciers affected by◦Average snowfall, adds to mass in winter◦Average warm temperatures- apur their

melting during the summer

Europe’s Alps◦Glaciers are

disappearing South America

◦Glaciers are disappearing

Greenland◦Warmer

temperatures Areas of Glacial Ice Melting

in Greenland

Largest island: 80% composed of glaciers

10% of the world’s fresh water

1996–2007: net loss of ice doubled

Effect on sea level if melting continues

Expansion of warm water and melting of land based ice–

Water will rise 18-59 cm (0.6-1.9 feet) during this century

storm surges of 6 meters (20 feet)

accompanying tropical cyclones and tsunamis

◦ Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs

◦ Disruption of coastal fisheries

◦ Flooding of Low-lying barrier islands

and coastal areas Agricultural lowlands and

deltas◦ Contamination of

freshwater aquifers◦ Submergence of low-

lying islands in the Pacific and Indian Oceans and the Caribbean

Maldives- Indian Ocean

Melting of permafrost in tundra soils releases methane and carbon di oxide

Loss of arctic tundra-reduce grazing lands for caribou

Boreal vegetation would replace tundra

Melting glaciers, particularly in Greenland Increased rain in the North Atlantic Could add enough fresh water to disrupt the

flow of deep and shallow ocean currents Could climate of Northern Europe. N. America

and Japan

Not thought to be an immediate problem on the ocean currents

Heat waves and droughts in some areas- kill people, reduce crop production, expand deserts

Prolonged rains and flooding(flash floods) from heavy and prolonged precipitation

Will storms get worse? ◦ More studies needed – Saunders and Lea (2008)

Hurricanes Katrina and Rita – lost 320 million big trees

Most susceptible ecosystems◦ Coral reefs◦ Polar seas◦ Coastal wetland◦ High-elevation mountaintops◦ Alpine and arctic tundra

Changes in water temperature, relative to coral bleaching threshold

30% of land –based plants and animals will disappear (temp change 1.5-2.5*C)

What about◦ Migratory animals◦ Forests

Some organisms will increase◦ Insects, Fungi,

Microbes Exploding populations of mountain pine beetles

Destroy lodge pole pine forests

Regions of farming may shift◦ Decrease in tropical and subtropical areas◦ Increase in northern latitudes◦ Overall food productivity would decrease because

of less productivity soil◦ Decrease in food production in farm regions

dependent on rivers fed by snow melt

Genetically engineered crops more tolerant to drought

Deaths from heat waves will increase

Deaths from cold weather will decrease

Higher temperatures can cause◦ Increased flooding◦ Increase in some forms of air pollution, more O3

◦ More insects, microbes, toxic molds, and fungi

Norman Myers – 150 to 200 million environmental refugees in this century

To slow the rate of global warming and climate change, we can

increase energy efficiency, sharply reduce greenhouse gas emissions, rely more on renewable energy resources slow population growth.

Governments can subsidize energy efficiency and renewable

energy use, tax greenhouse gas emissions, set up cap-and-trade emission reduction

systems, help to slow population growth.

Global problem

Long-lasting effects

Long-term political problem

Harmful and beneficial impacts of climate change unevenly spread

Many proposed actions disrupt economies and lifestyles

Two approaches◦ Drastically reduce the amount of greenhouse gas

emissions◦ Recognize that some warming is unavoidable and

devise strategies to reduce the harmful effects of global warming

Will we reach a political tipping point before we reach irreversible climate change tipping points?

Input or prevention strategies◦ Improve energy efficiency to reduce fossil fuel use◦ Shift from non-renewable carbon-based fossil

fuels to a mix of carbon-free renewable energy resources

◦ Stop cutting down tropical forests Output strategy

◦ Capture and store CO2 -

Socolow and Pacala◦ Climate stabilization wedges ◦ Keep CO2 emissions to 2007 levels by 2057

Brown: need to do more◦ Cut CO2 emissions by 80% by 2020

◦ 2008 book: Plan B 3.0: Mobilizing to Save Civilization

Output solutions◦ Massive global tree planting – 4 billion need to be

planted Wangari Maathai Great Wall of Trees: China and Africa

◦ Plant fast-growing perennials such as switch grass on degraded land which takes carbon dioxide from the air and stores it in the soil. Can be used to produce ethanol

Fig. 19-13, p. 515

SOLUTIONS

Global Warming

Prevention CleanupCut fossil fuel use (especially coal)

Remove CO2 from smokestack and vehicle emissionsShift from coal to natural gas Store (sequester) CO2 by planting treesImprove energy efficiencySequester CO2 deep underground (with no leaks allowed)

Shift to renewable energy resources

Transfer energy efficiency and renewable energy technologies to developing countries

Sequester CO2 in soil by using no-till cultivation and taking cropland out of production

Reduce deforestation Sequester CO2 in the deep ocean (with no leaks allowed)

Use more sustainable agriculture and forestry

Repair leaky natural gas pipelines and facilitiesLimit urban sprawl

Reduce poverty Use animal feeds that reduce CH4 emissions from cows (belching)

Slow population growth

Fig. 19-14, p. 515

Stepped Art

Fig. 19-15, p. 516

Oil rigTanker delivers CO2 from plant to rig

Coal power plant

Tree plantation

CO2 is pumped down from rig for disposal in deep ocean or under seafloor sediments

Abandoned oil field

Switchgrass Crop field

CO2 is pumped

underground

Spent oil or natural gas reservoir

Spent coal bed cavern

Deep, saltwater-filled cavern

= CO2 pumping

= CO2 deposit

Some Output Methods for Removing CO2 from the Atmosphere and storing it

Carbon capture and storage (CCS) – involves removing carbon dioxide from the smoke stacks of coal- burning power and industrial plants and storing them somewhere

Several problems with this approach◦ Power plants using CCS

More expensive to build None exist

◦ Unproven technology◦ Large inputs of energy to work◦ promotes continued use of coal◦ Effect of government subsidies and tax breaks◦ Stored CO2 would have to remain sealed forever:

no leaking

CCS – large scale geo engineering scheme opposed by scientists because long term effects on earth’s energy flow, chemical cycling processes and vital biodiversity are unknown

Injection of sulfate particles into the stratosphere by balloons, large jet planes, giant cannons

Huge amounts of sulfur dioxide injected into the atmosphere every 2 years◦ Would it have a cooling effect?◦ Would it accelerate O3 depletion?

Remove HCl from seawater – reduce ocean acidity. How would it affect the ecology ?

Pump up nutrient-rich deep ocean water and cause algal blooms, remove carbon dioxide and emit dimethyl sulfide which will contribute to the formation of low clouds that would reflect sunlight

Re-ice the Arctic – 8,000 ice making barges Wrap large areas of the glaciers with

insulating blankets

Short-term costs lower

Local and global economies may be boosted

Provide jobs because of new technology associated with alternative energy

Less expenses for remediation

Strictly regulate CO2 and CH4 as pollutants Cap-and-trade approach-political advantage carbon taxes - levy energy taxes on each unit

of fossil fuel that is burned – tax pollution, not payrolls

Increase subsidies to encourage use of energy-efficient technology

Technology transfer-fund the transfer of green technologies to phase out older, energy wasting technologies

1997: Treaty to slow climate change -2200 delegates from161 nations

1st phase – 174 of the world’s 194 countries (but not US) ratifying the agreement by mid -2008.

The Kyoto Protocol◦ Reduce emissions of CO2, CH4, and N2O by 2012 to

levels of 1990◦ Trading greenhouse gas emissions among countries◦ Not signed by theUS.(2001) 67% of ppublic upset

President G.W. Bush’s reasons-would harm US economyCap and Trade systems need to have the caps set low to

increase value of the tradable allowances

2004: Stewart and Wiener◦ New treaty needed

Should be led by the U.S.

Include China, India, Brazil and other developing countries that are getting industrialized and will be soon emitting the more than 50% of the world’s greenhouse gases

Cap-and-trade emissions program

Set up achievable 10 year goals – to reduce greenhouse gases over the next 40 years

Costa Rica: goal to be carbon neutral by 2030 – 78% from hydroelectric,18% from wind and geothermal

Norway: aims to be carbon neutral by 2050 China and India must change energy habits U.S. cities and states (27+ DC: solar and wind)

taking initiatives to reduce carbon emissions 650 cities around the world, including 453 US

cities reduce greenhouse gases Portland, Oregon – 1993-2005 greenhouse

gases at 1990 levels

Use of energy-efficient appliances and buildings

Incentives for consumers to use less energyHas saved California from building 24 new power

plants

California sued the EPA so that they and 17 other states can set tougher emission standards

Major global companies reducing greenhouse gas emissions- reduce 10-65% below 1990 levels by 2010◦ Alcoa◦ DuPont◦ IBM◦ Toyota◦ GE◦ Wal-Mart $12 million /year saved by using LED’s

Fluorescent light bulbs Auxiliary power units on truck fleets – no idling Carbon Disclosure Project

Colleges and universities reducing greenhouse gas emissions◦ Oberlin College, Ohio, U.S.◦ 25 Colleges in Pennsylvania, U.S.◦ Yale University, CT, U.S.

Largest teach-In Feb 2008-1500 colleges, climate change and sustainability

Reduce greenhouse gas emissions as much as possible (50-85% cut in by 2050) to prevent the planet from heating up by 2*C

Move people from low-lying coastal areas

Limit coastal building

Remove hazardous material storage tanks away from the coast

Genetically engineer crops more tolerant to drought

Stockpile 1–5 years of key foods

Waste less water

Connect wildlife reserves with corridors

Fig. 19-17, p. 522

Develop crops that need less water

Waste less water

Connect wildlife reserves with corridors Move people away

from low-lying coastal areas

Move hazardous material storage tanks away from coast

Stockpile 1- to 5-year supply of key foods

Prohibit new construction on low-lying coastal areas or build houses on stilts

Expand existing wildlife reserves toward poles

Which do you think is the most important ?

Widespread use of certain chemicals has reduced ozone levels in the stratosphere, which allows for more harmful ultraviolet radiation( UV-A and UV-B) to reach the earth’s surface.

To reverse ozone depletion, we must stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals.

Ozone Thinning ◦ Seasonal depletion

in the stratosphere Antarctica and

Arctic not in tropics

1930: Midgely◦ Discovered the

first CFC 1984: Rowland

and Molina ◦ CFCs (freons)were

depleting O3

Others – halons, hydrobromofluorocarbons (HBFC’s), methyl bromide, hydrogen chloride, carbon tetrachloride, methyl chloroform

1988 – less severe ozone thinning over Arctic from February to June, loss of 11-38%When this mass of air breaks up, large masses of ozone depleted air flow south to linger over parts of Europe, N.America,Asia

Research◦CFCs are persistent in the atmosphere◦Rise into the stratosphere over 11-20 years◦Break down under high-energy UV radiation Halogens produced accelerate the

breakdown of O3 to O2

◦Each CFC molecule can last 65-385 years 1988: Dupont stopped producing CFCs –

stalled for 15 years(1974) 1995: Nobel Prize in chemistry

Fig. 19-D, p. 525

SunUltraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2.

UV radiation ClO + O → Cl + O2

Repeated many times

Cl + O3 → ClO + O2

Summary of Reactions CFCl3 + UV → Cl + CFCl2

ClCl Cl

F C ClCl F Cl

Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again.Cl O

OO

OzoneO

O

O O O O

A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2. O

Cl

O

O

OO

The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO).

O OCl

The chlorine atom attacks an ozone (O3) molecule,pulling an oxygen atom off it and leaving an oxygen molecule (O2).

C

Damaging UV-A and UV-B radiation ◦ Increase eye cataracts and skin cancer

Impair or destroy phytoplankton- Antarctic base of food web loss of removal of carbon dioxide from the

atmosphere – worsening global warming

Fig. 19-20, p. 524

Stepped Art

Effects of ozone depletion

Fig. 19-E (1), p. 526

This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer.

This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma.

Thin layer of dead cells

Squamous cells

Epidermis

Basal layer Sweat gland

Melanocyte cells Dermis

Blood vesselsBasal cell

Ultraviolet A

Ultraviolet B

Hair

Fig. 19-E (2), p. 526

Thin layer of dead cells

Squamous cells Epidermis

Basal layer Sweat gland

Melanocyte cellsDermis

Blood vesselsBasal cell

Hair

This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer.

This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma.

Ultraviolet A Ultraviolet B

Fig. 19-E, p. 526

Stepped Art

Basal Cell Carcinoma MelanomaSquamous Cell Carcinoma

Stop producing all ozone-depleting chemicals 60(1980 levels)–100(1950 levels) years of

recovery of the O3 layer 1987: Montreal Protocol – 36 nations, cut

down 35% emissions between1989-2000 1990 – London – 93 countries 1992: Copenhagen Protocol-191 countries

Ozone levels should return to 1980 level by 2068(15 years later than predicted) and 1950 levels by 2108

Substitutes for CFCs are available More are being developed

HCFC-22 worst, phase out chemical by 2020 in

developed and 2030 in developing countries, 10 years earlier than agreed in 1992◦ Substitute chemical◦ May still be causing ozone depletion