why delaying emission reductions is a gamble

Why delaying emission reductions is a gamble

Steffen Kallbekken & Nathan Rive

Received: 28 March 2005 /Accepted: 12 July 2006 / Published online: 8 March 2007# Springer Science + Business Media B.V. 2007

Abstract In the debate on the timing of greenhouse gas emissions reductions the aspect ofpolitical feasibility has often been missing. We introduce this aspect and show that, if wedecide to delay emissions reductions, and the environmental effectiveness of globalmitigation efforts is to remain the same in terms of temperature change, we must be willingand able to undertake much more substantial emission reductions than with early action. Evenunder conservative assumptions on initial political feasibility (maximum 0.25% year-on-yearreductions), a 20-year delay means that we must reduce emissions at an annual rate that is 5 to11 times greater than with early climate action. Our capacity for technological progress,political change and the inertia of the socio-economic system gives us reason to be concernedabout our ability to achieve such higher rates of emission reductions. If we are not able toachieve such higher rates, delaying action will inevitably result in higher temperatures in2100. Unless we are willing to accept higher temperatures, choosing to delay climate action isa gamble that political feasibility will increase over time as a result of the delay itself.

1 Introduction

While there is general agreement that achieving the objectives of the United NationsFramework Convention on Climate Change (United Nations 1992) will require long-termreductions in greenhouse gas (GHG) emissions, there has been much debate concerning thetiming and magnitude of these reductions. Both these choices depend on the long-termclimate goals we seek to achieve through mitigation. In principle there are an infinitenumber of global emission reduction pathways that can satisfy any given long-term target.The choice of pathway has received significant attention in the literature. Wigley et al.(1996) argued that in light of slow capital turnover, and technological improvement withtime, significant emissions reductions should be postponed, Grubb (1997) counter-arguedfor near-term abatement by highlighting the abatement technologies available today, the

Climatic Change (2007) 82:27–45DOI 10.1007/s10584-006-9179-2

S. Kallbekken (*) : N. RiveCICERO Center for International Climate and Environmental Research – Oslo,P.O. Box 1129, Blindern, 0318 Oslo, Norwaye-mail: [email protected]

importance of induced technological change and learning-by-doing, and the risks ofsignificant long-term climate impacts.

The idea that it may be preferable to delay climate action and focus instead on near-termcapacity improvements, has given rise to proposals to undertake alternative agreements(such as technology agreements) in place of quantitative emissions reductions (e.g.,Schmalensee 1996). A technology agreement might prove better than the targets andtimetables approach of the Kyoto Protocol at attracting signatories and achieving globalmitigation efforts (without saying anything about the scale of the efforts). The USA, Japan,Australia, China, India and South Korea signed the Asia–Pacific Partnership on CleanDevelopment and Climate in July 2005. This agreement aims to ‘develop and acceleratedeployment of cleaner, more efficient energy technologies’ (White House 2006). However,while a pure technology agreement would improve our capacity for mitigation, it would notguarantee emissions reductions as there would not be any economic incentives orrequirements for adopting the technologies.

In this paper, we focus on the aspect of political feasibility in the discussion on thetiming of GHG abatement. Building on a definition of how political feasibility constrainswhat global emissions reductions can be achieved, this paper aims to:

& Examine the relationship between the timing of abatement and the shape of mitigationtrajectories that result in the same long-term temperature change;

& Highlight the implications of delaying climate action on the rates of abatement requiredto meet the same target; and

& Identify what conditions must be satisfied – in the context of some key determinants ofpolitical feasibility – if we are to be able to meet the same target under delayed action.

In the next section, we discuss political feasibility and define how the term will be usedfor the purposes of this study. The next two sections describe the Models and Scenarios anddiscuss the Delaying Climate Action. Sensitivity Analysis is followed by a Discussion onthe implications of early versus delayed climate action and ended with Conclusions.

2 Political feasibility

In the literature on long-term climate agreements, it has often been assumed or implied thatthe approach to climate policy will be consistent, rational, and knowledgeable. Thispresumption (or hope) of rationality is reflected, for example, in studies which developoptimal long-term climate policies that account for both the costs and benefits of mitigationpolicy (e.g., Nordhaus and Boyer 2001). An alternative, the Tolerable Windows Approach,takes the impacts of climate change as a starting point, and works out emissions trajectoriesconsistent with avoiding particular impact thresholds. The social, economic and politicalimplications of these alternative trajectories are then evaluated to determine which are‘tolerable’ (see for example Petschel-Held et al. 1999).

We would argue that it is more realistic to assume that future agreements on emissionsreductions will be based on what is politically feasible at each point in time – rather than onsome optimized or cost-effective long-term mitigation scenario. The important point that isoften missed is that political feasibility is the link between costs and benefits and whatemissions reductions are agreed upon in a climate agreement. While economicconsiderations are important, they are only one of the several factors that influence whatfuture climate agreements might look like. Political feasibility is determined by such

28 Climatic Change (2007) 82:27–45

constraints as the trade-off between the economic, environmental, social, and political costsand benefits of mitigation – particularly for the most influential political actors – as well asconcerns such as enforcement, public pressure, government willingness to spend politicalcapital, fairness and burden-sharing.1

In terms of climate policy, when all these factors that determine political feasibility havebeen traded off against each other, the end outcome is the emissions reductions thatcountries commit themselves to. For the purposes of this paper we will focus on the globalaggregate of the emissions reductions. That is, we will not look at the national level; wewill not make any assumptions about whether the aggregate global reductions are the resultof one global climate regime, multiple regional or sectoral agreements, or domestic policiesalone; and we will consequently not make any assumptions about burden-sharing betweencountries. Thus, in this paper, we define ‘political feasibility’ as the maximum globalaggregate rate of emissions reductions that can be achieved in a given year.

This non-optimizing view of climate policy is mirrored elsewhere. Philibert et al. (2003)comment that while we may all agree that our current GHG emissions are too high, aconsensus may never be reached about the risks of climate change or the appropriatemitigation action. Thus, future agreements could simply be incremental reductions based onpolitical and economic acceptability. Furthermore, in approaching the climate changeproblem, we may become a victim of what Homer-Dixon (2000) terms the ‘ingenuity gap’:“the critical gap between our need for ideas to solve complex problems and our actualsupply of those ideas.” That is, climate change mitigation and adaptation may be toocomplex to manage, and impossible to solve with a rational or optimal approach given thelimited and uncertain information and resources we have. In such an instance, we may beforced to take an incremental approach to emissions reductions.

It is impossible to say precisely how all the contributing factors to political feasibilitywill change over time, how they may impact climate policy, or indeed be impacted byclimate policy. In this paper, we focus on what we consider to be four key factors in thediscussion on delaying climate action. These factors are chosen because they are all amongthe principal determinants of political feasibility, and because there are plausibleexplanations as to how they will vary depending on whether action is taken early or late.

The first such factor is the development and adoption of low emissions technologies.Concerns of abatement costs and economic impacts are likely to be of primary importancein negotiations, and were highlighted as the key reason for US withdrawal from the KyotoProtocol (White House 2001). Technology is therefore a particularly relevant factor asinvention, innovation, and diffusion of alternative energy technologies can reduce the costsof mitigation.

The second factor is the inertia inherent in the structure of our energy and economicsystems. It has for example been argued that we should postpone significant near-termabatement to avoid the costly early retirement of our existing capital stock (Wigley et al.1996). Yet there is also the risk of a carbon ‘lock-in’ of our technologies and institutions(Unruh 2000; IPCC 2001b). This may limit our economies’ ability to break free fromcarbon energy dependence, particularly in the near-term.

1 Policies are of course not some direct product of the various political pressures that have a bearing on theissue at hand. Politicians have their own goals which they wish to pursue. But, their ability to pursue thesegoals is constrained by external factors such as public opinion and lobbying, and it is the changes in theseexternal constraints that we are concerned with here.

Climatic Change (2007) 82:27–45 29

Political pressure is a third determinant of what climate policies are feasible. Suchimportant factors as public opinion and the political clout of different interest groups maydepend significantly on the timing of climate action.

A fourth factor we consider is scientific uncertainty regarding the climate system andimpacts. This uncertainty could lead to an argument that we should adopt a ‘wait and see’approach and wait until we have better information before acting. Yet the scientificuncertainty may not be resolved in the coming decades.

Finally, it is important to note that it is the goals of individuals, and how we go aboutachieving these goals, that drives the activities that create emissions of greenhouse gases. TheIPCC (2001b; 367) argues that “[p]erhaps the most significant barriers to GHG mitigation,and yet the greatest opportunities, are linked to social, cultural and behavioural norms andaspirations.” Changes in preferences or in the consumption patterns used to satisfy thesepreferences can have a great impact on the feasibility of emissions reductions (as well asbeing a method for reducing emissions in itself). However, while behavioural and socialchange can certainly have important implications for the timing of emissions reductions, it isa very complex issue, and we consider it to be beyond the scope of this paper.

3 Models and scenarios

In the next two sections, we create illustrative model scenarios to assess the relationshipbetween political feasibility, the timing of mitigation, and the environmental effectivenessof our long-term climate action. This is done in two parts. In this section, we compare long-term temperature change under Early Action with Delayed Action scenarios, where we keepthe assumptions on political feasibility constant (assume it is independent of mitigationtiming), but change the number of years by which emissions reductions are delayed. In“Delaying Climate Action” we use the same Early Action scenarios as in this section, andfind out what annual rates of emissions reductions must be politically feasible if we are toachieve the same long-term temperature change with a delay in mitigation as with EarlyAction. These scenarios are labeled Compensated Action.

3.1 Assumptions on environmental effectiveness

We use the global mean temperature increase in 2100 (above pre-industrial levels) as anindicator to describe and compare the environmental effectiveness of our long-termmitigation scenarios. While the UNFCCC (United Nations 1992) mandates the avoidanceof ‘dangerous interference with the climate system,’ it is difficult to define what isdangerous, and how we should frame a long-term target for the climate system. Long-termtargets have been proposed in terms of stabilization concentrations, allowable temperatureincrease and sea level rise (see below). These targets may or may not be used to frame ournear-term reductions, but can still be a useful input to decision-making (Corfee-Morlot andHöhne 2003). We use 2100 as the year for evaluating temperature change, as it is typicallyfound in the literature. The European Commission (European Environment Agency 1996)and the WBGU (1995), for example, defined targets in terms of a maximum tolerabletemperature change limit of 2.0°C above pre-industrial levels in 2100. It should be notedthat while we use long-term temperature as a measurement of environmental effectiveness,we are not assuming that a long-term target could be agreed upon, or that one target ispreferable over another; we use it only as a means of comparing the environmentaleffectiveness of early and delayed action.


We could have also chosen to define environmental effectiveness in terms of the rate ofwarming, as this may be equally critical in terms of ‘dangerous’ climate change as themagnitude of change (Rijsberman and Swart 1990). In a study on this issue O’Neill andOppenheimer (2004) find that “The likelihood of occurrence of impacts that might beconsidered dangerous increases under trajectories that delay emissions reduction orovershoot the final concentration.” A number of studies have framed long-term climateobjectives in terms of both the magnitude and rate of temperature change (EnquetteKommission 1991; WBGU 1995; Yohe and Toth 2000). Given our policy assumptions, theCompensated action scenarios (see “Delaying Climate Action”) will invariably producehigher peak rates of temperature change than early action. While we will report the rates ofchange in “Delaying Climate Action,” we will not discuss them further – as our modelassumptions are not geared towards investigating this issue.

3.2 Emission scenarios and models

For the first part of our analysis, we develop a set of emissions scenarios for the period1997 to 2100, in which we asses the long-term temperature impact of early vs. delayedmitigation strategies for a range of delays and maximum feasible abatement rates. We take ageneralized approach, and assess a range of possible mitigation start years and a range ofmaximum rates of abatement. We use a range of 0%, 0.25%, 0.5%, 0.75%, 1.0%, and1.25% maximum (year-on-year) annual abatement rate, and consider a range of 5-, 10-, 15-,20-, and 25-year delays.

First, we develop a set of Early Action scenarios for each maximum feasible abatementrate. For these scenarios, when the commitments under the Kyoto Protocol expire in 2012,we assume a new agreement will be in place in 2013 wherein the global GHG emissionswill follow a 20-year (mitigation) transition trajectory towards achieving the maximumfeasible abatement rate. Second, we develop a set of Delayed Action scenarios, for eachcombination of maximum feasible abatement rate and delay timing in our range. Instead ofbeginning mitigation action in 2013, each scenario will first follow the BAU trajectory forthe prescribed delay period before beginning a 20-year transition trajectory towardsachieving the maximum feasible abatement rate.

Once the scenarios achieve the maximum rate, it is assumed to remain at that rate until2100. There are several reasons why this would not happen. This is for simplicity, and weignore learning-by-doing (and similar) effects. See Fig. 1 for an illustration of the Earlyand Delayed cases, and the Appendix for a further description of the scenarios.

The scenarios are generated in the Dynamic analysis of the Economics of EnvironmentalPolicy (DEEP) model. The DEEP model is a multi-sector, multi-regional, multi-gasdynamic computable general equilibrium (CGE) model (Kallbekken 2004, used inKallbekken and Westskog 2005) calibrated around the GTAP database (Dimaranan andMcDougall 2002). For this project, the model was set up with only one world region, andwas run with a time horizon of 1997–2100. DEEP includes industrial emissions of CO2,CH4, and N2O. See the Appendix for a further description.

In the Early Action scenarios, we employ economic growth and technologicalimprovement parameters from the SRES A1B scenario (Nakicenovic and Swart 2000).For the Delayed Action scenarios, we generate two sets using the parameters from the A1Band B2 scenarios, to account for the uncertainty in emissions growth in the interveningBAU period from 2013 when a delay is undertaken. To make these two sets equal until2013, however, we use A1B parameters until that point. This setup allows us to illustratethe impact of the decision of mitigation timing at a point in time (2013) under the


uncertainty of future BAU emissions. We do not explicitly assume any global emissionslevel or regional participation rate to represent the Kyoto Protocol, given its uncertainty andthe minor impact on temperatures in 2100.

In our scenarios, emissions reductions are undertaken with global emissions tradingacross the three GHGs in the model.2 For the emissions that are either not included in theDEEP model (F-gases), and/or not covered in the Kyoto Protocol (aerosols, CO2 from land-use change, CH4/N2O/SO2 from natural sources) we follow the trajectory from the SRESA1B emission scenario (Nakicenovic and Swart 2000).

Industrial SO2, however, we include by scaling the absolute level to industrial emissionsof CO2. This is because they are largely determined by changes in combustion, and theymake a large and negative contribution to radiative forcing. Thus, they may have an impacton our results. The SO2:CO2 scaling factor used is exogenous, but changes over time: wefollow the factor from the SRES A1B scenario.

The emission scenarios are fed into the CICERO Simple Climate Model (SCM)(Fuglestvedt et al. 2000). The SCM calculates global mean concentrations from emissionsof 29 GHGs and radiative forcing for 35 components (including stratospheric andtropospheric O3, and direct and indirect effects of aerosols). It incorporates a scheme forCO2 (Joos et al. 1996) and an energy-balance climate/up-welling diffusion ocean model(Schlesinger et al. 1992). A further description of the model is found in the Appendix. In

2 We assume that the climate agreement allows inter-gas emissions trading using GWP100 as the conversionfactor. While this might not be the best approach (see Fuglestvedt et al. (2003) for a discussion on the metricsof climate change), it is the approach used in the Kyoto Protocol.

Fig. 1 Annual global GHG emissions (Gt Ce) from DEEP (CO2, CH4, N2O) for a set of Early, Delayed andCompensated Action scenarios with an initial abatement rate of 0.75% and a delay of 20 years


this project we use climate sensitivities based on the probability density function developedby Murphy et al. (2004). Specifically, we use the median value of the 95% confidenceinterval, which equals a 3.5°C temperature increase in 2100 for a doubling of atmosphericCO2-concentrations from pre-industrial levels. The radiative forcings from sulphateaerosols (direct and indirect) are based on the median value of the 95% confidence intervalfrom Andronova and Schlesinger (2001). The direct forcing is then −0.25 W/m2 and theindirect forcing is −0.65 W/m2.

Using the SCM model we obtain temperature change projections for 2100 for each of theemission scenarios. Table 1 shows the projected temperature change in 2100 for the Earlyaction scenario, and the Delayed action scenarios for each combination of feasibleabatement rate and mitigation delay.

Comparing the Early and Delayed action scenarios, we find that if the political feasibilityconstraint does not change, then the global mean temperature in 2100 will be 0.04–0.9°Chigher if we delay action than if we take early action.

4 Delaying climate action

In considering delaying climate action as an alternative to early action, we now ask whatannual emission reductions (of industrial CO2, CH4 and N2O) are required if we are toachieve the same environmental effectiveness with late action as with early action. In otherwords, we ask how much the political constraints must be relaxed (in terms of achievableannual emissions reductions) during the years of no abatement (i.e., delay) if the late actionis to be at least as good as early action from an environmental point of view. We refer tothese as Compensated Action scenarios.

We use an iterative algorithm that runs both the DEEP model and the SCM to find therequired emission reductions for each combination of initial Early action maximumabatement rate and delay. The algorithm runs the DEEP model with an initial reductionfactor, starts up the SCM model to find what temperature change (in 2100) the emission

Table 1 Global mean temperature change in 2100 (°C above pre-industrial levels) under Early Action(mitigation start in 2013) and under Delayed Action A1B and B2 for alternative maximum feasible rates ofabatement. The entry c.s. denotes that the DEEP model cannot solve this combination of delay and abatementrate, because a constant emissions trajectory from the 20- and 25-year delay ends up above the BAU level

Rate of abatement (%) 0 0.25 0.50 0.75 1.00 1.25

Early Action 3.4 3.3 3.2 3.1 3.0 2.9Delayed Action A1B5-year delay 3.6 3.5 3.4 3.3 3.2 3.110-year delay 3.7 3.6 3.5 3.4 3.4 3.315-year delay 3.9 3.8 3.7 3.6 3.5 3.520-year delay c.s. 3.9 3.8 3.7 3.7 3.625-year delay c.s. 4.1 3.9 3.9 3.8 3.8

Delayed Action B25-year delay 3.5 3.3 3.2 3.2 3.1 3.010-year delay 3.5 3.4 3.3 3.3 3.2 3.115-year delay 3.6 3.5 3.4 3.4 3.3 3.220-year delay 3.7 3.6 3.5 3.5 3.4 3.325-year delay 3.7 3.6 3.6 3.5 3.5 3.4


scenario generated by DEEP will result in, and compares this temperature to the targettemperature. If the achieved temperature is above (below) the target the algorithm will thenincrease (decrease) the reduction factor. The algorithm keeps repeating this procedure untilthe achieved temperature is within 0.05°C of the temperature target. Figure 1 illustrates asample set of Early, Delayed, and Compensated Action scenarios that correspond to aninitial abatement rate of 0.75% and a delay of 20 years.

Table 2 shows what Compensated Action abatement rates are required under delayedaction in order to achieve the same temperatures in 2100 as with Early action. We find thatto account for the delay, the Compensated Action cases must undertake a rate of emissionsreduction that is several times greater than their associated Early Action case in order toachieve the same long-term temperature target. For example, with an Early Actionabatement rate of 0.25% and a delay of 20 years, the Compensated maximum annual rate ofabatement must be between 1.3% and 2.7%; 5 to 11 times the original value. For an EarlyAction abatement rate of 1% and a delay of 20 years, the Compensated maximum annualrate of abatement must be between 3.0% and 4.8%.

The emissions growth during the period with no mitigation drives our results, whichshould come as no surprise. This is because the emissions during the no action period mustbe offset by emissions reductions at a later date. The main reason emissions reductions haveto be dramatically greater if we delay mitigation is the fact that climate change depends oncumulative emissions. If cumulative emissions are to be the same, and you have emittedmore during the first years or decades, you need to emit less during the remaining years.This simple relationship has particularly important implications when one considers annualrates of temperature change. The long response time for CO2 and the inertia of the climatesystem (IPCC 2001a) also contributes to this result.

In Fig. 2 we show the decadal rate of temperature change produced under Early,Delayed, and Compensated action scenarios with an assumed Early action reduction rate of0.25% and a delay of 20 years for the 3.5°C climate sensitivity. The figure shows that forEarly action the maximum decadal rate of temperature change is 0.30°C. The maximumrate is only slightly higher, at 0.33°C for the Delayed action B2, but significantly higher at

Table 2 Required rate of abatement under Compensated Action to meet the same temperature change in2100 as in Early Action for a range of delays and initial rates of abatement. The entries c.s. indicate that theDEEP model could not solve, in this case because the required abatement rates were too high

Rate of abatement under Early Action (%) 0 0.25 0.50 0.75 1.00 1.25

Temperature change in 2100 (°C) 3.4 3.3 3.2 3.1 3.0 2.9Compensated Action A1B (%)5-year delay 0.3 0.6 0.9 1.3 1.6 1.910-year delay 0.8 1.1 1.5 1.9 2.3 2.715-year delay 1.4 1.8 2.3 2.8 3.3 3.920-year delay 2.1 2.7 3.3 4.1 4.8 5.325-year delay 3.2 4.0 4.9 c.s. c.s. c.s.

Compensated Action B2 (%)5-year delay 0.1 0.3 0.6 0.9 1.2 1.510-year delay 0.3 0.6 0.9 1.3 1.7 2.015-year delay 0.6 0.9 1.3 1.8 2.2 2.720-year delay 0.9 1.3 1.8 2.4 3.0 3.525-year delay 1.3 1.9 2.5 3.3 4.0 4.8


0.37°C for the Delayed action A1B scenario. These figures can also provide insight intotemperature development after 2100. In all our scenarios, global mean temperaturecontinues to rise after 2100. If we were seeking to attain a specific long-term temperaturetarget, we may be concerned with such ‘overshoot’, as the target would have beencompromised. It is the Early Action case that has higher rates of warming towards 2100.The drastic cuts from the Delayed Action case generate a significant slow-down inwarming, which will carry on into the next century. This suggests that if we are to avoidovershoot, significant reductions must be made in the latter stages of this century – a pointalso made in the literature (Wigley 2003).

5 Sensitivity analysis

A key assumption is that we compare environmental effectiveness by setting a temperaturetarget for the year 2100. This year holds no specific significance; it is simply the target yearthat has been chosen in many other studies (see the point on long-term targets). As lateaction requires that we in the later years keep our emissions below what they are with earlyaction, we are on an emissions path where late action will achieve a lower temperature thanearly action at some point in the future. Thus, the earlier we set the temperature target, themore the results favour early action. We tested the models with target years of 2110 and

Fig. 2 Decadal rate of temperature change (°C/decade) under Early, Delayed, and Compensated Actionscenarios with an initial rate of 0.25% and a delay of 20 years


2090. When running the DEEP model beyond 2100, we continue the same growth andtechnological improvement parameters as in 2100 to 2110. In both cases we comparerequired emission cuts under late action with the initial 0.25% cuts under Early Action inthe A1B scenario. With the standard target year of 2100, the annual emission cuts wererequired to be 2.7% under Delayed Action A1B. The new experiments show that for atarget year of 2110, the annual cuts must be 1.7%, and for a 2090 target they have to be4.0%. This shows that the results are quite sensitive with respect to the target year, yet stillstresses the implications of early versus delayed climate action.

We also consider the possible impact of our choice of climate sensitivity on the results.We find the impact is only found on the absolute temperature levels in the Early, DelayedCompensated results, and not in the ratio of Compensated: Early abatement rates. This isbecause of the linear temperature change assumption in our (and most other) simple climatemodel(s): ΔT=1RF, where ΔT is temperature change, 1 is climate sensitivity, and RF isradiative forcing. That is, marginal changes in climate sensitivity have a linear effect ontemperature, regardless of the emissions level. As such, the choice of climate sensitivity hasno impact on our Compensated Action results.

6 Discussion

The results show very clearly that in terms of upholding a given level of environmentaleffectiveness, we must be willing and able to undertake much more substantial emissionreductions if we decide to delay emissions reductions. What is remarkable is just how muchgreater (as much as 10 times) the annual emissions reductions must be as a result of a delay.Furthermore, these much more rapid emission cuts must be sustained not only for a fewyears – but for several decades. In terms of achieving any given long-term climate target,this means that if we want to wait before taking on binding emission reductions, instead ofundertaking what mitigation is feasible today, we must be certain that our capacity andwillingness for undertaking mitigation will improve substantially as a result of delayingaction.

The question, then, is whether we can expect political feasibility to improve to such anextent during the ‘no-action’ period. If delaying action is going to offer us any advantageswith respect to meeting the objective of the UNFCCC, feasibility must increase over timeas a direct consequence of the delay, and this increased level of political feasibility must besustained for the remainder of the mitigation period. Thus, our concern is with how thefactors that determine political feasibility will be affected by early or delayed action.

There are two important qualifications to this approach. First, if we are in a situationwhere what is politically feasible with early action is more than sufficient to safely meet theobjective of the UNFCCC (which we would argue is not the case) then we are in a positionto favour delayed action without risking that we will not meet the objective of the convention.Second, it is not given that we will want to reduce GHG emissions significantly, either ifclimate change turns out to be a less serious problem than the clear majority of climateresearchers believe today (for example if climate sensitivity should turn out to be at the lowerrange of current estimates), or if the willingness to accept climate change impacts should bemuch greater than we expect.

We will divide our discussion into sections corresponding to the four key factorsdescribed earlier; development and adoption of new technologies, the inertia of the socio-economic system, political pressure, and scientific uncertainty.


6.1 Development and adoption of low emission technologies

Technology, and technological change, has a significant impact on abatement costs, andthrough this on the political feasibility of emissions reductions. Thus, there are obviousimplications for the choice of timing of GHG abatement. If we delay climate action, butwish to maintain the same level of environmental effectiveness as with early action,technologies must develop in a direction and by a magnitude that will allow us to undertakereductions at lower cost. Delaying emission reductions would allow time for R&D, whileearly action may push innovation through induced technical change, and allow for learning-by-doing (see Wigley et al. 1996; Grubb 1997, among others). Many of the technologiesneeded for significantly reducing GHG emissions already exist, however, making thisequally much an issue of ensuring adoption of the relevant technologies.

Government policies to promote innovation can take a number of forms. However, duringthe ‘no action’ period – even if there are policies to invest in R&D etc. – the opportunity ismissed for taking advantage of two key innovation drivers – induced innovation and learning-by-doing. Thus, any increase in the rate of technological progress in the absence of mitigationmust come from other sources. Firstly, the unrestricted economic growth during the ‘noaction’ period may increase our capacity for technological progress. However, inducedinnovation policies and external price shocks have been of critical importance for improvingenergy efficiency – and autonomous energy efficiency improvements cannot be relied upon tosolve our problems (Schneider and Azar 2001). Alternatively, governments could undertakebasic R&D (or provide financial support for R&D) towards technological improvements.Government budgets for R&D have, however, fallen in the last two decades (Margolis andKammen 1999). A third option is the credible announcement of the start of climate policyahead of time by government, which would send a clear signal to the market and generate anincentive for private investment in R&D (Goulder 2004). Yet choosing not to take onbinding emissions reductions today, but announcing the intention to do so in the future, isnot necessarily sufficient to induce markets to invest in R&D as the ‘threat’ is made lesscredible by the fact that no binding reductions are implemented today; many of the reasonspresent for choosing to delay climate action today will also be there 20 years from now. Itwould be time-inconsistent to assume governments could commit to policies 20 years fromnow that they are not willing to undertake today.

Once an emissions reduction strategy is implemented, induced innovation and learning-by-doing will likely be key drivers of technological change. Historically, these have beenimportant. For example, improvements in fuel cell technology have been largely driven byCalifornia air quality legislation (Schneider and Azar 2001). External shocks, such as theenergy crises in the 1970s, can also be linked to significant efficiency improvements:Newell et al. (1998) look at durable energy using household goods, and find that prior to1973 the autonomous improvements were biased away from energy efficiency, but that theenergy crisis slowed or reversed this process. They estimate that post-1973 energy priceincreases account for 25% to 50% of observed improvements in energy efficiency inproducts offered for sale in the last two decades.

Modeling of induced innovation suggests that technological change will unlikely be thepanacea for stringent mitigation. Nordhaus (2002) finds that induced innovation will havesurprisingly little impact on abatement in the near-term compared to factor substitution (i.e.,substituting towards less emissions-intensive inputs rather than investing in new productiontechnologies). This could suggest that we take modest early action to avoid stringent ratesof emissions reductions in order to reduce the impact on the economy from substitution


requirements (which are efficiency decreasing – as opposed to technological improvementswhich can be efficiency enhancing).

Technological change does not, in itself, reduce emissions. The direction oftechnological change matters (even if emissions intensity is falling in all cases), and notechnology has any impact on emissions unless it is being used. A report by the OECD andIEA explains very clearly why the direction and type of technological change matters:

In the last decades, technical progress has significantly reduced costs in explorationand exploitation of oil and gas. Inasmuch as this has displaced much coal use, it hashelped mitigate climate change. However, where it has displaced nuclear power,energy efficiency efforts or renewable energy sources, it has contributed to increasinggreenhouse gas emissions. [OECD/IEA 2003; 9]

Furthermore, the report finds that “...there is no guarantee that strategies focusing onresearch and development (including dissemination efforts) of carbon-free technologies willnecessarily be successful. This is particularly true if technologies are developed undercurrent market conditions rather than with changes in the pricing of climate changeexternalities” (OECD/IEA 2003; 10).

A third important point in the discussion of the role of technology in mitigation is that newtechnologies do not reduce emissions in themselves; the technologies must also be made useof if they are going to have any effect. Many researchers have argued that to a large extent thetechnologies required for significant emissions reductions already exist. The IPCC is forexample quite optimistic in its assessment of the potential of existing technologies to reduceemissions: “...known technological options could achieve a broad range of atmospheric CO2

stabilization levels...” (IPCC 2001b; 8). But, the report also notes “[t]he transfer oftechnologies and practices that have the potential to reduce GHG emissions is oftenhampered by barriers that slow their penetration” (IPCC 2001b; 44). Thus, while existingtechnologies may have a great potential for reducing emissions (including some no-regretsoptions) there are various barriers to this potential being realized.

If low emissions technologies are going to be adopted at a greater rate than they are today,we need to overcome the barriers (which include information and consumption patterns), andwe need financial incentives to use these technologies. The IPCC (2001b; 441) argue that“[r]ates of invention, innovation, and technology diffusion are affected by opportunities thatexist for firms and individuals to profit from investing in research, in commercial development,and in marketing and product development.” Unless we use political instruments to createopportunities to profit from such investments, we will not make full use of the potential ofexisting technologies (or new technologies as they become available).

Furthermore, the adoption of new technologies will in itself help drive down the cost of thetechnologies, and make it profitable for more firms to adopt them. The reason is that the costsof a technology tend to decrease in proportion to the cumulative installed technology –typically by about 18% for each doubling of installed capacity (OECD/IEA 2000). OECD/IEA (2000) conclude that “If we want cost-efficient, CO2-migitation technologies availableduring the first decades of the new century [twenty-first], these technologies must be giventhe opportunity to learn in the marketplace. Deferring decisions on deployment will risklock-out of these technologies, i.e., lack of opportunities to learn will foreclose theseoptions making them unavailable to the energy system.”

The section has addressed the issue of the invention and innovation of alternative energytechnologies. An equally important concern is the diffusion and adoption of those


technologies, and the replacement of older energy technologies. This is related to the focusof the next section.

6.2 Inertia of the socio-economic system

The term ‘inertia of the socio-economic system’ refers to the fact that there are manyobstacles to making any major change in the socio-economic system; these obstaclesinclude avoiding costly premature retirement of the existing capital stock, and the ‘lock-in’to the current energy system. It means that implementing substantial change requires a greatdeal of time and effort, and it makes faster changes much more painful (and less politicallyfeasible) to society than more gradual changes.

The IPCC puts great emphasis on the issue of inertia in the discussion of the timing ofclimate action (IPCC 2001b; 658). Postponing significant action in the near-term would avoid‘premature retirement of existing capital stocks and takes advantage of the natural rate ofcapital stock turnover’ and allow more ‘time to retrain the workforce and for structural shiftsin the labour market and education’ (based on Wigley et al. 1996). However, the same reportalso focuses on the implications of technological ‘lock-in’: “A large percentage of capital isinvested in a relatively small number of technologies that are responsible for a significantshare of the energy supply and consumption market (automobiles, electric power generators,industrial processes, and building heating and cooling systems). There is a tendency tooptimize these few technologies and their related infrastructure development, gaining themadvantages and locking them into the economy” (IPCC 2001b; 172).

Comparing the Early and Compensated-action scenarios from this paper, we find that theissue of inertia and ‘lock-in’ provides significant arguments for preferring the Early-actionscenario. Firstly, while we seek to avoid premature retirement of the existing capital stock,we should also be concerned with the capital investments made in the coming decades. Forinstance, a large number of power plants will be built over the next few years, and will havean economic life-span of 30–40 years. Under the Compensated-action case, we can expectthat a greater number of these power plants will be fossil-fuel fired due to the absence ofclimate regulations. This will contribute further to the ‘lock-in’ to existing energytechnologies. Overcoming the ‘lock-in’ to power plants, as well as other parts of ourcarbon economy (i.e., transport infrastructure, maintenance, training), does not becomeeasier by extending our existing energy infrastructure.

Another significant ‘lock-in,’ with an even longer time horizon, concerns urban formand urban infrastructure. IPCC (2001b; 657) argues that “structures of urban form andurban land-use can only be changed over 100 years.” Many countries are currently goingthrough a period of significant population growth and rapid urbanization. The urbanplanning decisions made over the next couple of decades will lay down the urban form forseveral decades (or even centuries) to come. Urban planning has a significant impact on theenergy efficiency of cities – not least through the transport demands created by the urbanform, and the possibilities for public transportation.

A paper by Ha-Duong et al. (1997) focuses explicitly on the implications of socio-economic inertia and uncertainty on the timing of mitigation, in trading off the risk of costlypremature abatement versus the risk of costly efforts to accelerate abatement if strongeraction is called for after a period of delay. They find that “early attention to the carbon-emitting potential of new and replacement energy systems will minimize the risk toenvironmental and economic systems.”


The ‘lock-in’ to existing energy infrastructures suggests that rapid rates of change will bepainful to the economy and result in high welfare losses. While this could suggest that weshould seek to avoid stringent action in the near-term, this arguments neglects that delayedaction will require a much higher rate of mitigation sustained for several decades. Thishigher rate of mitigation could be painful to future economies, given the inertia in the socio-economic system and that we may need to overcome future ‘lock-in’ scenarios (as we havein the past, see Unruh 2002). Taking early action will allow us to avoid the severe socio-economic impacts of rapid mitigation requirements in the future.

6.3 Political pressure

Technological change and socio-economic inertia are factors that determine the costs andgains of climate policies. These costs and gains become political factors through publicopinion and the political clout of the potential winners and losers.

Sprinz and Weiß (2001) highlight the role of domestic political concerns in internationalclimate policy. They argue that in international negotiations “government positions arelikely to be influenced by domestic pressure groups in anticipation of the challenges posedby ratification” (Sprinz and Weiß 2001, p.67). These domestic pressure groups include theelectorate, industry lobby groups and non-governmental organizations (NGOs). Theinterests and political clout of these groups will change over time; the electorate mightgrow more concerned about climate change as they witness its impacts, industries mightfavour research into alternative energy sources if oil prices remain high, and NGOs willlikely respond to new scientific discoveries on climate change.

One possibility is that with delayed action, the public and businesses will be exposed togreater climate impacts at an earlier stage, and might thus grow more concerned aboutclimate change and demand stronger action. However, given the lag in the climate system,climate impacts will continue to rise in the near-term regardless of what action is takenduring the next one or two decades (IPCC 2001c). Thus, such impacts in the near termwould affect public pressure in the Early action case as well – and fail to create any‘additional’ public pressure that would improve political feasibility under the Compensatedaction case. Indeed, public and business acceptance for climate mitigation policies mayimprove the longer policies to reduce emissions have been in place – as institutionalcapabilities expand and implementation uncertainties are resolved. Schneider and Azar(2001) argue that “[e]arly abatement increases awareness about the potential risksassociated with carbon emissions. This awareness builds social acceptance for carbontaxes, energy efficiency standards or other policies and measures.”

An additional argument is that it takes time to create the political institutions required toimplement emission reduction policies, in part due to lengthy political negotiations wherediffering national interests must be reconciled. One of the main arguments as to why theKyoto Protocol is important (despite the modest impact it will have on long-term climatechange) is that it establishes an institutional framework that will allow us to make greateremissions reductions in the future. This institutional inertia may go well beyond theinstitutions associated with the climate agreement as such. Some proponents of knowledge-based theories of international regimes argue that “[o]nce ideas have become embodied ininstitutional frameworks, they constrain public policy as long as they are not undermined bynew scientific discoveries or normative change” (Hasenclever et al. 1996; 207) and thatthrough the intervention of institutions the impact of ideas may be prolonged for decades oreven generations” (Hasenclever et al. 1996; 208). This could imply that if, for instance, a


technology agreement (with mandated investments in R&D but without binding emissionsreduction commitments) was chosen over an explicit mitigation agreement, it would createpressures to prolong the technology agreement beyond the time it was originally envisagedthat it would be replaced with a mitigation agreement; as the idea of a technology agreementwould by then have been institutionalized in research, business and government activities.

6.4 The implications of scientific uncertainty

Several significant scientific uncertainties concerning our knowledge of the climate systemremain. Uncertainty regarding the climate sensitivity (e.g., Andronova and Schlesinger2001; Murphy et al. 2004) means that we cannot know except within very broad rangeswhat near- or long-term action is required to safely meet the Article 2 mandate of theUNFCCC (Rive et al. 2007). The implication is that we may risk undertaking expensivemitigation efforts that may turn out to be unnecessary, or that we risk experiencing severeclimate impacts as a result of inadequate action (Grubb 1997). This uncertainty could leadto an argument that we should adopt a ‘wait and see’ approach and delay action, as withfuture improvements in our knowledge of the climate system, we will have a better idea ofwhat mitigation is necessary.

Another connection between the timing debate and increased knowledge about climatechange is that as regional and local downscaling improves, and impact studies give clearerand more robust indications of who will be the winners and losers as the climate changes,the stakeholders will participate more actively in the policy debate. For example, as ourknowledge improves concerning whether and when the northwestern passage may becomepassable as the extent of Arctic sea ice decreases, shipping agencies might possibly take ona role in advocating climate adaptation over mitigation. This is one mechanism throughwhich increased knowledge may lead to decreasing public pressure to reduce emissions.

Yet the scientific uncertainty may not be resolved in the coming decades. We may stillbe left with an incomplete picture of what is required in order to avoid ‘dangerous’ climateinterference (see Andronova and Schlesinger 2001, for historical calculations of climatesensitivity), and face the same dilemma as we do today. Yohe et al. (2004) show that giventhese uncertainties, a modest near-term hedging strategy (i.e., emissions reductions) wouldgo a long way toward reducing future abatement costs and ensuring that a number of long-term climate options remain open. Similarly, in a paper that looks at the risk of melting ofthe Western Antarctic Ice Shelf and the Greenland Ice Shelf, Oppenheimer and Alley(2005) conclude that “[r]egardless of whether 1, 2, 4°C global warming, or 10°C localwarming, or some other value turns out to be a useful limit in the context of Article 2, delayin reducing emissions would substantially increase the risk of entering the danger zone.”

From the perspective of managing the risks associated with our still limitedunderstanding of the climate system, there are some strong arguments in favour ofimmediate emissions reductions. It is, however, not obvious how the state of scientificknowledge will change depending on whether we choose early or delayed action.

7 Conclusions

In this paper we assume that political feasibility is the binding constraint on what can beachieved in terms of global GHG emissions reductions. Rather than taking an optimizinglong-term approach to the climate problem, we assume the world will undertake only


whatever mitigation is politically feasible at each point in time. As such, we define‘political feasibility’ as the maximum possible rate of global emissions reductions. Wecompare the warming and mitigation rates of Early climate action (starting in 2013) andDelayed/Compensated climate action (starting 5–25 years later).

From this comparison we draw two main findings:

& If the feasible rate of emission reductions remains the same, temperature change in 2100is likely to be roughly 0.5°C (0.04–0.9°C) higher in the Delayed Action cases ascompared to Early action. Given the current warming of 0.5°C above pre-industriallevels, and the 2°C warming limit in 2100 advocated by the European Commission, anypolicy choice that increases emissions puts us at greater risk of overstepping thethresholds of what could be deemed as ‘dangerous’ climate change.

& If we are to ensure that global warming in 2100 is not any greater as a result of delayingaction, the rate of mitigation under Compensated Action must be up to 10 times fasterthan under Early action. While the precise numbers are dependent on the Early Actionabatement rate and the period of delay, our key finding is not: To achieve the samelong-term temperature change under delayed climate action, political feasibility mustimprove substantially in the intervening ‘no action’ period and be maintained at a highlevel over the entire duration of the mitigation period.

This result is driven by the necessity to reduce emissions from a higher starting point inless time with Compensated action than with Early Action, and the inertia of the climatesystem. Emissions during the intervening period of non-action must be compensated forwith deeper emissions cuts in later years under the delayed action case (see Fig. 1). Whatshould make us concerned about this result is the inertia of the socio-economic system,which puts limits on how fast we are able to restructure our energy system and reduce GHGemission. If deeper emission cuts are to be possible, we must experience improvements inthree key determinants of political feasibility:

& Technological improvements must produce lower abatement costs during the period ofno climate action, and once mitigation has commenced, the technological improvementsmust be sustained at a higher rate than with early action. Furthermore, existing and newlow emissions technologies must also be taken into use at a faster rate – despite the lackof incentives from emission reduction requirements to do so;

& The inertia and carbon ‘lock-in’ of the socio-economic system must not hinder higherrates of abatement now or in the future;

& Public pressure towards climate action must increase as a result of delaying policies,and business interests must allow for a higher rate of mitigation.

These improvements must in some way be directly related to the period of no action, andthey must be sustained throughout the mitigation period. There are many reasons why thisis unlikely to happen. That is why we claim, given that we need to reduce global GHGemissions significantly, that those who wish to delay climate action are gambling thatpolitical feasibility will not limit our ability to reduce emissions in the future.

Acknowledgments This work was supported by a grant from the Norwegian Research Council. The authorsare grateful for the useful inputs from Kristin Aunan, Guri Bang, Terje Berntsen, Jan S. Fuglestvedt, OddGodal, Lynn P. Nygaard, Asbjørn Torvanger, Hege Westskog and Asbjørn Aaheim and three anonymousreviewers.


Appendix

When generating our scenarios (in all cases), we assume a 20-year transition period fromthe start of mitigation action (the deviation from the BAU trajectory) to the achievement ofthe maximum feasible rate of abatement, as illustrated in Fig. 1. The transition scenario isgenerated through a simple linear interpolation of the year-on-year change in annualemissions in the start year (i.e., 2013) to the end of the transition (i.e., 2033) when themaximum abatement rate is achieved. Because this methodology will cause the finalabatement rate to impact the point at which the peak emissions level (0% year-on-year changein emissions) occurs, we generate a standardized peak using a maximum abatement rate of 1%.

CO2 emissions are modeled in DEEP with a fixed factor composite input to productionof each primary energy input and CO2 emissions permits (with constant CO2 emissions perunit energy input). CO2 abatement thus occurs through substitution away from theindividual energy inputs. Non-CO2 emissions are modeled in a fashion similar to the EPPAmodel (Hyman et al. 2002). Emissions permits of CH4 and N2O are direct inputs to theproduction function at the top level nest of the production structure. CH4 and N2Oreduction occurs through substitution away from the emissions permits, leading to anincrease in the use of all other inputs. Substitution elasticities are taken from Hyman et al.In the model, the emissions intensity of production falls over time in accordance with anassumed exogenous rate of technological improvement. See also Kallbekken (2004).

The SCM is described in Fuglestvedt and Berntsen (1999) and used in e.g., Fuglestvedtet al. (2000). The model incorporates a scheme for CO2 from Joos et al., (1996) and anenergy-balance climate/up-welling diffusion ocean model developed by Schlesinger et al.(1992). The CO2 module uses an ocean mixed-layer pulse response function thatcharacterizes the surface to deep ocean mixing in combination with a separate equationdescribing the air–sea exchange based on the HILDA model (Siegentaler and Joos 1992) toaccount for non-linearities in the carbon chemistry in the ocean. For CH4 the lossparameterisation is taken from IPCC Third Assessment report (TAR) (IPCC 2001a) Section4.2.1.1; i.e., 9.6 years for loss due to tropospheric OH, 120 years for stratospheric loss, and160 years for the soil sink. For the remaining non-CO2 gases, simple decay functions basedon atmospheric lifetimes are used. Development in tropospheric O3 as a function ofemissions of NOx, CO, VOC and CH4 is also taken from TAR (IPCC 2001a, table 4.11,note b), and tropospheric O3 forcing in 1990 is set to 0.34 Wm−2. Forcings from fossil-fuelblack carbon and organic carbon aerosols, biomass burning aerosols, stratospheric O3 andwater vapor are calculated as described in IPCC TAR (2001a) and Harvey et al. (1997). Theconcentration-forcing relations are based on IPCC (1999) and IPCC TAR (2001a), and theyare non-linear for CO2, N2O and CH4. The overlap term between N2O and CH4 is includedas in IPCC TAR (2001a).

References

Andronova NG, Schlesinger ME (2001) Objective estimation of the probability density function for climatesensitivity. J Geophys Res 106(D19):22605–22612

Corfee-Morlot J, Höhne N (2003) Climate change: long-term targets and short-term commitments. GlobEnviron Change 13:277–293

Dimaranan BV, McDougall RA (2002) Global Trade, Assistance, and Production: The GTAP 5 Data Base,Center for Global Trade Analysis, Purdue University


Enquette Kommission (1991) Preventative Measures to Protect the Earth’s Atmosphere. In: Protecting theEarth: a status report with recommendations for a new energy policy, German Bundestag, Bonn

European Environment Agency (1996) Climate change in the European Union. European EnvironmentAgency, Copenhagen

Fuglestvedt JS, Berntsen T (1999) A simple model for scenario studies of changes in global climate: Version1.0. Working Paper 1999:02, CICERO, Oslo

Fuglestvedt JS, Berntsen T, Godal O, Skodvin T (2000) Climate implications of GWP-based reductions ingreenhouse gas emissions. Geophys Res Lett 27(3):409–412

Fuglestvedt JS, Berntsen TK, Godal O, Sausen R, Shine KP, Skodvin T (2003) Metrics of climate change:assessing radiative forcing and emission indices. Clim Change 58(3):267–331

Goulder LH (2004) Induced technological change and climate policy. Report prepared for the Pew Center onGlobal Climate Change, Arlington

Grubb M (1997) Technologies, energy systems and the timing of CO2 emissions abatement – an overview ofeconomic issues. Energy Policy 25(2):159–172

Ha-Duong M, Grubb MJ, Hourcade JC (1997) Influence of socioeconomic inertia and uncertainty on optimalCO2-emission abatement. Nature 390:270–273

Harvey D, Gregory J, Hoffert M, Jain A, Lal M, Leemans R, Raper S, Wigley T, Wolde J de (1997) Anintroduction to simple climate models used in the IPCC second assessment report. IPCC Technical PaperII, Intergovernmental Panel on Climate Change, Geneva, Switzerland

Hasenclever A, Mayer P, Rittberger V (1996) Interests, power, knowledge: the study of international regimes.Mershon Int Stud Rev 40:177–228

Homer-Dixon T (2000) The ingenuity gap. Alfred A. Knopf, New YorkHyman RC, Reilly JM, Babiker MH, De Masin, Jacoby HD (2002). Modeling non-CO2 greenhouse gas

abatement. MIT Joint Program on the Science and Policy of Global Change, Report no. 94IPCC (1999) Aviation and the global atmosphere – a special report of IPCC working groups I and III.

Cambridge University Press, Cambridge, UKIPCC (2001a) Climate change 2001: the scientific basis. Intergovernmental panel on climate change.

Cambridge University Press, Cambridge, UKIPCC (2001b) Climate change 2001: mitigation. Intergovernmental panel on climate change. Cambridge

University Press, Cambridge, UKIPCC (2001c) Climate change 2001: impacts, adaptation, and vulnerability. Intergovernmental panel on

climate change. Cambridge University Press, Cambridge, UKJoos F, Bruno M, Fink R, Stocker TF, Siegenthaler U, Le Quéré C, Sarmiento JL (1996) An efficient and

accurate representation of complex oceanic and biospheric models of anthropogenic carbon uptake.Tellus 48B:397–417

Kallbekken S (2004) A description of the Dynamic analysis of Economics of Environmental Policy (DEEP)model, CICERO Report 2004:01, CICERO, Oslo

Kallbekken S, Westskog H (2005) Should developing countries take on binding commitments in a climateagreement? An assessment of gains and uncertainty. Energy J 26(3):41–60

Margolis RM, Kammen DM (1999) Underinvestment: the energy technology and R&D policy challenge.Science 285:690–691

Murphy JM, Sexton DMH, Barnett DN, Jones GS, Webb MJ, Collins M, Stainforth DA (2004)Quantification of modelling uncertainties in a large ensemble of climate change simulations. Nature430:768–772

Nakicenovic N, Swart R (eds) (2000) Special report on emission scenarios. Cambridge University Press,Cambridge, UK

Newell RG, Jaffe AB, Stavins RN (1998) The induced innovation hypothesis and energy-savingtechnological change. Q J Econ 114(458):941–975

Nordhaus WD (2002) Modeling induced innovation in climate change policy. In: Grubler A, Nakicenovic N,Nordhaus WD (eds) Modeling induced innovation in climate change policy. Resources for the Future,Washington, District of Columbia

Nordhaus WD, Boyer J (2001) Warming the world. MIT, Boston, MassachusettsOECD/IEA (2000) Experience Curves for Technology Policy. OECD/EIA, ParisOECD/IEA (2003) Technology Innovation, Development and Diffusion. OECD/IEA Information Paper

COM/ENV/EPOC/IEA/SLT(2003)4, OECD/EIA, ParisO’Neill BC, Oppenheimer M (2004) Climate change impacts are sensitive to the concentration stabilization

path. Proc Natl Acad Sci USA 101(47):16411–16416Oppenheimer M, Alley RB (2005) Ice sheets, global warming, and article 2 of the UNFCCC: An Editorial

Essay. Clim Change 68(3):257–267


Petschel H, Schellnhuber HJ, Bruckner T, Tóth FL, Hasselmann K (1999) The tolerable windows approach:theoretical and methodological foundations. Clim Change 41(3–4):303–331

Philibert C, Pershing J, Corfee-Morlot J, Willems S (2003) Evolution of mitigation Commitments: some keyissues, OECD and IEA Information Paper, OECD/IEA, Paris

Rijsberman FR, Swart RJ (eds) (1990) Targets and indicators of climatic change. Report of Working Group IIof the Advisory Group on Greenhouse Gases (AGGG), Stockholm Environmental Institute, Stockholm

Rive N, Torvanger A, Berntsen T, Kallbekken S (2007) To what extent can a long-term temperature targetguide near-term climate change commitments? Clim Change, doi:10.1007/s10584-006-9193-4

Schlesinger M, Jiang EX, Charlson RJ (1992) Implications of anthropogenic atmospheric sulphate for thesensitivity of the climate system. In: Rosen L, Glasser R (eds) Climate change and energy policy:proceedings of the international conference on global climate change. American Institute of Physics,New York, pp 75–108

Schmalensee R (1996) Greenhouse Policy Architecture and Institutions, MIT Joint Program on the Scienceand Policy of Climate Change, Report 13, Cambridge, Massachusetts

Schneider SH, Azar C (2001) Are uncertainties in climate and energy systems a justification for strongernear-term mitigation policies? Report prepared for Pew Center on Global Climate Change, Arlington

Siegentaler U, Joos F (1992) Use of a simple model for studying oceanic tracer distributions and the globalcarbon cycle. Tellus 44B:186–207

Sprinz DF, Weiß M (2001) Domestic politics and global climate policy. In: Luterbacher U, Sprinz DF (eds)International relations and global climate change. MIT, Cambridge, Massachusetts

United Nations (1992) United Nations framework convention on climate change, UNFCCC. http://www.unfccc.int/. Cited 2006

Unruh GC (2000) Understanding carbon lock-in. Energy Policy 28(12):817–830Unruh GC (2002) Escaping carbon lock-in. Energy Policy 30(4):317–325WBGU (German Advisory Council on Global Change) (1995) Scenarios for the derivation of global CO2

reduction targets and implementation strategies, WBGU, Bremerhaven, GermanyWhite House (2001) President Bush Discusses Global Climate Change, 11.06.2001. Internet: White house

http://www.whitehouse.gov/news/releases/2001/06/20010611-2.html. Cited on 2006White House (2006) Fact Sheet: The Asia-Pacific Partnership on Clean Development and Climate, Press

release 11.01.2006. Internet: http://www.whitehouse.gov/news/releases/2006/01/20060111-8.html. Citedon 2006

Wigley T (2003) Modelling climate change under no-policy and policy emissions pathways. Paper preparedfor the OECD Project on the Benefits of Climate Policy, 12–13 December 2002 (ENV/EPOC/GSP(2003)7/FINAL, OECD, Paris

Wigley TML, Richels R, Edmonds JA (1996) Economic and environmental choices in the stabilisation ofatmospheric CO2 concentrations. Nature 379:242–245

Yohe G, Toth FL (2000) Adaptation and the guardrail approach to tolerable climate change. Clim Change45(7):103–128

Yohe G, Andronova N, Schlesinger M (2004) To hedge or not against an uncertain climate future? Science306:416–417


http://dx.doi.org/10.1007/s10584-006-9193-4

http://www.unfccc.int/

http://www.unfccc.int/

http://www.whitehouse.gov/news/releases/2001/06/20010611-2.html

http://www.whitehouse.gov/news/releases/2006/01/20060111-8.html

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