Avoiding Dangerous Anthropogenic Interference with the Climate System

The UN Framework Convention on Climate Change calls for the avoidance of “dangerous anthropogenic interference with the climate system”. Among the many plausible choices, dangerous interference with the climate system may be interpreted as anthropogenic radiative forcing causing distinct and widespread climate change impacts such as a widespread demise of coral reefs or a disintegration of the West Antarctic ice sheet. The geological record and numerical models suggest that limiting global warming below critical temperature thresholds significantly reduces the likelihood of these eventualities. Here we analyze economically optimal policies that may ensure this risk-reduction. Reducing the risk of a widespread coral reef demise implies drastic reductions in greenhouse gas emissions within decades. Virtually unchecked greenhouse gas emissions to date (combined with the inertia of the coupled natural and human systems) may have already committed future societies to a widespread demise of coral reefs. Policies to reduce the risk of a West Antarctic ice sheet disintegration allow for a smoother decarbonization of the economy within a century and may well increase consumption in the long run.     

Increasing impacts of climate change upon ecosystems with increasing global mean temperature rise

In a meta-analysis we integrate peer-reviewed studies that provide quantified estimates of future projected ecosystem changes related to quantified projected local or global climate changes. In an advance on previous analyses, we reference all studies to a common pre-industrial base-line for temperature, employing up-scaling techniques where necessary, detailing how impacts have been projected on every continent, in the oceans, and for the globe, for a wide range of ecosystem types and taxa. Dramatic and substantive projected increases of climate change impacts upon ecosystems are revealed with increasing annual global mean temperature rise above the pre-industrial mean (ΔT_g). Substantial negative impacts are commonly projected as ΔT_g reaches and exceeds 2°C, especially in biodiversity hotspots. Compliance with the ultimate objective of the United Nations Framework Convention on Climate Change (Article 2) requires that greenhouse gas concentrations be stabilized within a time frame “sufficient to allow ecosystems to adapt naturally to climate change”. Unless ΔT_g is constrained to below 2°C at most, results here imply that it will be difficult to achieve compliance. This underscores the need to limit greenhouse gas emissions by accelerating mitigation efforts and by protecting existing ecosystems from greenhouse-gas producing land use change processes such as deforestation.     

Climate or development: is ODA diverted from its original purpose?

We analyze the interaction of climate and development policy that has taken place since the early 1990s. Increasing dissatisfaction about the results of traditional development cooperation and the appeal of climate policy as a new policy field led to a rapid reorientation of aid flows. At the turn of the century, over 7% of aid flows were spent on greenhouse gas emissions mitigation. However, the contribution of emissions mitigation projects to the central development objective of poverty reduction as specified in the Millennium Development Goals is limited and other project types are likely to be much more effective. Adaptation to climate change can be expected to have higher synergies with poverty alleviation than mitigation, primarily through its impact on health, the conservation of arable land and the protection against natural disasters. An analysis of the Clean Development Mechanism shows that projects addressing the poor directly are very rare; even small renewable energy projects in rural areas tend to benefit rich farmers and the urban population. Use of development aid for CDM projects and / or their preparation via capacity building is thus clearly not warranted. We further analyze whether the use of development aid for climate policy could be justified as a countermeasure against the emission increase related to successful development itself. However, countries that are achieving an improvement of human development from a low level are unlikely to increase their energy consumption substantially. Only at a level where the middle class expands rapidly, energy consumption and greenhouse gas emissions soar. Thus targeting middle class energy consumption by appliance efficiency standards and public transport-friendly urban planning are the most effective measures to address developing country emissions. Rural renewable energy provision in poor countries has a much higher impact on poverty, but a much lower impact on greenhouse gas emissions. We conclude that while there are valid reasons for long-term collaboration with emerging economies on greenhouse gas mitigation, there should be a separate budget line for such activities to avoid “obfuscation” of a decline of resources aimed at poverty alleviation. Nevertheless, mitigation will remain attractive for donors because it ensures quick disbursements and relatively simple measures of success. Moreover, mitigation activities in developing countries provide politicians in industrialized countries with a welcome strategy to divert the attention of their constituencies from the lack of success in reducing greenhouse gas emissions domestically.     

An evaluation of the level of ambition and implications of the Bush Climate Change Initiative

Abstract

This article summarises the results of an evaluation of the Climate Change Initiative launched by President Bush in February 2002. The policy target to reduce the greenhouse gas intensity of the US economy by 18% between 2002 and 2012 can be considered modest at best. The Initiative is likely to result in a 32% increase in US greenhouse gas emissions in 2012 compared to the 1990 levels. The effort also falls considerably short of efforts of the EU, Japan and Canada under the Kyoto Protocol. The Bush Initiative advocates using intensity targets in the international climate change regime, but overlooks fundamental problems associated with this approach. All the same, the Bush Initiative is of political significance as it recognises the importance of the climate change problem and may improve the longer-term prospects for US participation in a global climate regime.     

An equity first, risk-based framework for managing global climate change

This paper presents an alternative framework to the approach currently embodied in the Kyoto Protocol for managing global climate change post-2012. The framework has two key provisions. The first is that each person in the world would be ‘allowed’ an equal amount of greenhouse gas (GHG) emissions. This is labeled the equity-first provision. The second provision focuses on incorporating risk concepts into the setting of GHG emission reductions. It is proposed that the global climate be managed as to avoid three categories of risks: (I) Substantial regional economic, political, and/or biological impacts; (II) Severe global economic, political, and/or biological impacts; and (III) Extinction of humans. Acceptable risk thresholds are suggested to be one-in-a-million, one-in-one-hundred-million, and one-in-ten-billion, respectively. This equity-first, risk-based framework overcomes many criticisms of the current Kyoto Protocol: it explicitly involves all countries on earth; it avoids several administrative issues that are anticipated to plague a global carbon emissions trading market; and it avoids several contentious issues associated with pegging carbon emission reductions to 1990 levels. Because the framework is risk-based and emissions are tied to population and not historic emission levels, the basic framework would not have to be frequently renegotiated, as will be needed for the Kyoto-style approach to take the world past that agreement's 2012 endpoint.     

Testing 100-Year Global Warming Potentials: Impacts on Compliance Costs and Abatement Profile

The comprehensive approach adopted in the Kyoto Protocol relies on the use of 100-year Global Warming Potentials (GWPs) to convert emissions of various gases to `carbon dioxide (CO<sub>2</sub>) equivalents'. This particular set of weights, or metric, has a limited capacity to handle the large variations in atmospheric adjustment times, and emissions of various gases that are equal in terms of `CO₂ equivalents' will not result in equal climatic effects. In this study, the 100-year GWP metric is assessed in the context of implementing the Kyoto Protocol. Using data from Norway, we explore how abatement policy formulated on the basis of 100-year GWPs compares to policies based on other metrics in terms of compliance costs and abatement profile, that is, the composition of the basket of gases reduced. We found that the costs for Norway change significantly when other metrics are used, but changes in the composition of the basket of gases are moderate. However, since compliance costs can be controlled through other mechanisms for post-Kyoto Protocols, the use of 100-year GWPs versus other metrics has little impact on the general formulation of Norwegian climate policy.     

Climate protection and newly industrialized countries: dilemmas and opportunities in Taiwan

Global climate policy currently is making efforts to mitigate greenhouse gas emissions of industrialized countries through implementation of the Kyoto Protocol. Yet, the development of greenhouse gas emissions in newly industrialized and developing countries is deeply influencing the perspectives of stabilizing the global climate system. This study takes a closer look at the challenges facing Taiwan as an illustrative example to analyze the trends of greenhouse gas emissions, to assess current strategies and their controversies, and to explore strategies for mobilizing national climate policies. Analyzing the aspects of emission caps, carbon taxes, and clean development mechanisms may shed light on the necessity of involving newly industrialized countries and joint reduction into global climate protection schemes. Hopefully, this analysis may provide inspiring insights about the international climate regime and to other newly industrialized and developing countries which can then adopt effective policies for stabilizing the global climate system.     

Responsibility for Past and Future Global Warming: Uncertainties in Attributing Anthropogenic Climate Change

During the negotiations on the Kyoto Protocol, Brazil proposed a methodology to link the relative contribution of Annex I Parties to emission reductions with the relative contributions of Parties to the global-mean temperature increase. The proposal was not adopted during the negotiations but referred to the Subsidiary Body for Scientific and Technological Advice for consideration of its methodological aspects. In this context we analyze the impact of model uncertainties and methodological choices on the regionally attributed global-mean temperature increase. A climate assessment model has been developed to calculate changes in greenhouse gas concentrations, global-mean temperature and sea-level rise attributable to individual regions. The analysis shows the impact of the different choices in methodological aspects to be as important as the impact of model uncertainties on a region's contribution to present and future global temperature increases. Choices may be the inclusion of the anthropogenic non-CO₂ greenhouse gas emissions and/or theCO₂ emissions associated with land-use changes. When responsibility to global temperature change is attributed to all emitting Parties, the impacts of modeling uncertainties and methodological choices on contributions of individual Parties are considerable. However, if relative contributions are calculated only within the group of Annex I countries, the results are less sensitive to the uncertainty aspects considered here.     

Values for a post-Kyoto discourse

Environmental policy, including the Kyoto Protocol, is laden with values. Recognizing this fact can help UNFCCC parties come to agreement. Much of the contention surrounding the post-Kyoto negotiations can be explained through a framework of values. This article summarizes the arguments used by proponents and critics of emissions trading of greenhouse gas emissions under the Kyoto Protocol through such a framework of values. Proponents and critics of emissions trading espouse common values, such as achievement, to work toward ameliorating climate change; there is less agreement on emissions trading seen through values such as responsibility and fairness. As non-Annex I parties are expected to take a more active role in the second commitment period, identifying values held by those working on their behalf will facilitate negotiations and help develop a discourse that is inclusive of their interests. Annex I parties can also benefit from the identification of the values to better convey their interests. All parties can use the values framework identified here to construct a more durable climate change regime.     

A rose by any other name ...?: What members of the general public prefer to call “climate change”

Unlike many other environmental problems, the terms used to describe the phenomenon of increasing atmospheric concentrations of anthropogenic greenhouse gases are many, with multiple and sometimes conflicting meanings. Whether there are meaningful distinctions in public perceptions of “global warming,” “climate change,” and “global climate change” has been a topic of research over the past decade. This study examines public preferences for these terms based on respondent characteristics, including climate change beliefs, political affiliation, and audience segment status derived from the “Global Warming’s Six Americas” classification. Certainty of belief in global warming, political affiliation and audience segment status were found to be the strongest predictors of preference, although “I have no preference” was the modal response. Global warming appears to be a more polarizing term than climate change, preferred most by people already concerned about the issue, and least by people who don’t believe climate change is occurring. Further research is needed to identify which of these two names promotes the engagement of people across the spectrum of climate change beliefs in constructive dialogue about the issue.     

Impact of a climate network: The role of intermediaries in local level climate action

Local governments have set highly ambitious greenhouse gas emission reduction targets on a strategic level, in some cases influenced by intermediary networks. Yet, the quantitative impacts of climate strategies or the sharing of best practices on emissions still remain largely unknown. The aim of this study was to examine the impact of an intermediary network on municipal greenhouse gas emissions. This was done through an econometric analysis of the emissions of municipalities that are members of the Finnish Hinku (Towards Carbon Neutral Municipalities) network, and through comprehensive qualitative interviews conducted in 40 of those municipalities. Our quantitative results show that Hinku network membership has successfully led to the lowering of greenhouse gas emission levels in participating municipalities. The qualitative interviews suggest that this is due to systematic local level climate work, enhanced by network membership. The network functions as an intermediary in two ways: by providing expertise and enabling peer-support. In addition, it has also succeeded in legitimising local level climate action. Ambitious local level climate action can also affect the ambition of national climate policy, which in turn may reflect on the amount resources allocated to local climate action.     

Catastrophic Outcomes in the Economics of Climate Change

Monte Carlo simulations by Tol (2003) suggest that there is a small but positive probability that climate change will impose catastrophic impacts on future society unless sufficient steps are taken to reduce greenhouse gas emissions. This paper critically evaluates this finding and its implications for policy analysis and decision-making.     

The AVOID programme’s new simulations of the global benefits of stringent climate change mitigation

Quantitative simulations of the global-scale benefits of climate change mitigation are presented, using a harmonised, self-consistent approach based on a single set of climate change scenarios. The approach draws on a synthesis of output from both physically-based and economics-based models, and incorporates uncertainty analyses. Previous studies have projected global and regional climate change and its impacts over the 21st century but have generally focused on analysis of business-as-usual scenarios, with no explicit mitigation policy included. This study finds that both the economics-based and physically-based models indicate that early, stringent mitigation would avoid a large proportion of the impacts of climate change projected for the 2080s. However, it also shows that not all the impacts can now be avoided, so that adaptation would also therefore be needed to avoid some of the potential damage. Delay in mitigation substantially reduces the percentage of impacts that can be avoided, providing strong new quantitative evidence for the need for stringent and prompt global mitigation action on greenhouse gas emissions, combined with effective adaptation, if large, widespread climate change impacts are to be avoided. Energy technology models suggest that such stringent and prompt mitigation action is technologically feasible, although the estimated costs vary depending on the specific modelling approach and assumptions.     

The economics (or lack thereof) of aerosol geoengineering

Anthropogenic greenhouse gas emissions are changing the Earth’s climate and impose substantial risks for current and future generations. What are scientifically sound, economically viable, and ethically defendable strategies to manage these climate risks? Ratified international agreements call for a reduction of greenhouse gas emissions to avoid dangerous anthropogenic interference with the climate system. Recent proposals, however, call for a different approach: to geoengineer climate by injecting aerosol precursors into the stratosphere. Published economic studies typically neglect the risks of aerosol geoengineering due to (i) the potential for a failure to sustain the aerosol forcing and (ii) the negative impacts associated with the aerosol forcing. Here we use a simple integrated assessment model of climate change to analyze potential economic impacts of aerosol geoengineering strategies over a wide range of uncertain parameters such as climate sensitivity, the economic damages due to climate change, and the economic damages due to aerosol geoengineering forcing. The simplicity of the model provides the advantages of parsimony and transparency, but it also imposes severe caveats on the interpretation of the results. For example, the analysis is based on a globally aggregated model and is hence silent on intragenerational distribution of costs and benefits. In addition, the analysis neglects the effects of learning and has a very simplistic representation of climate change impacts. Our analysis suggests three main conclusions. First, substituting aerosol geoengineering for CO₂ abatement can be an economically ineffective strategy. One key to this finding is that a failure to sustain the aerosol forcing can lead to sizeable and abrupt climatic changes. The monetary damages due to such a discontinuous aerosol geoengineering can dominate the cost-benefit analysis because the monetary damages of climate change are expected to increase with the rate of change. Second, the relative contribution of aerosol geoengineering to an economically optimal portfolio hinges critically on, thus far, deeply uncertain estimates of the damages due to aerosol forcing. Even if we assume that aerosol forcing could be deployed continuously, the aerosol geoengineering does not considerably displace CO₂ abatement in the simple economic optimal growth model until the damages due to the aerosol forcing are rather low. Third, substituting aerosol geoengineering for greenhouse gas emission abatement can fail an ethical test regarding intergenerational justice. Substituting aerosol geoengineering for greenhouse gas emissions abatements constitutes a conscious risk transfer to future generations, in violation of principles of intergenerational justice which demands that present generations should not create benefits for themselves in exchange for burdens on future generations.     

Development of a risk-hedging CO2-emission policy, part I: Risks of unrestrained emissions

A rational global strategy with respect to greenhouse-gas emissions would seek to minimize total risk, which is the sum of the risk of negative impacts due to climatic change associated with a given level of emissions, and the risks associated with the process of achieving that emission level. Given the existence of reducible uncertainties in estimating these risks, and the possibility that an emission target thought to minimize total risk is later found to be not strict enough, a risk-hedging strategy is a more realistic policy objective. This paper is Part I of a two-part series in which these risks are reviewed and an interim risk-hedging emission level is proposed. Here, the risks associated with unrestrained greenhouse-gas emissions are reviewed. In particular, the carbon-cycle response to continuing CO₂ emissions; the heat trapping of projected greenhouse gas increases in comparison to other anthropogenic and natural heating or cooling perturbations; the climatic response to heating perturbations; and the impacts of projected climatic change on global agriculture, forests, coastal regions, coral reefs, water resources, terrestrial species, stratospheric and tropospheric ozone, and human comfort and welfare are critically examined. It is concluded that unrestrained emissions of greenhouse gases pose real and substantial risks to human societies and to ecosystems, and that these risks are likely to grow substantially if the climate warms beyond that associated with a CO₂ doubling. These risks clearly justify some action to limit emissions. The magnitude of emission restraint that is justified depends not only on the risks reviewed here, but also on the risks associated with measures to limit greenhouse-gas emissions, which are reviewed in Part II.     

Biofuels and carbon management

Public policy supports biofuels for their benefits to agricultural economies, energy security and the environment. The environmental rationale is premised on greenhouse gas (GHG, “carbon”) emissions reduction, which is a matter of contention. This issue is challenging to resolve because of critical but difficult-to-verify assumptions in lifecycle analysis (LCA), limits of available data and disputes about system boundaries. Although LCA has been the presumptive basis of climate policy for fuels, careful consideration indicates that it is inappropriate for defining regulations. This paper proposes a method using annual basis carbon (ABC) accounting to track the stocks and flows of carbon and other relevant GHGs throughout fuel supply chains. Such an approach makes fuel and feedstock production facilities the focus of accounting while treating the CO₂ emissions from fuel end-use at face value regardless of the origin of the fuel carbon (bio- or fossil). Integrated into cap-and-trade policy and including provisions for mitigating indirect land-use change impacts, also evaluated on an annual basis, an ABC approach would provide a sound carbon management framework for the transportation fuels sector.     

Differentiating Future Commitments on the Basis of Countries’ Relative Historical Responsibility for Climate Change: Uncertainties in the ‘Brazilian Proposal’ in the Context of a Policy Implementation

During the negotiations on the Kyoto Protocol, Brazil proposed allocating the greenhouse gas emission reductions of Annex I Parties according to the relative effect of a country’s historical emissions on global temperature increase. This paper analyses the impact of scientific uncertainties and of different options in policy implementation (policy choices) on the contribution of countries’ historical emissions to indicators of historical responsibility for climate change. The influence of policy choices was found to be at least as large as the impact of the scientific uncertainties analysed here. Building on this, the paper then proceeds to explore the implications of applying the Brazilian Proposal as a climate regime for differentiation of future commitments on the global scale combined with an income threshold for participation of the non-Annex I regions. Under stringent climate targets, such a regime leads to high emission reductions for Annex I regions by 2050, in particular for Europe and Japan. The income threshold assumptions strongly affect the Annex I reductions, even more than the impact of another burden-sharing key. A variant of the Brazilian Proposal, allocating emission reductions on the basis of cumulative emissions since 1990, would lead to a more balanced distribution of emission reductions.     

The modification of greenhouse gas warming by the direct effect of sulphate aerosols

 The Canadian Centre for Climate Modelling and Analysis (CCCma) second generation climate model (GCMII) consists of an atmospheric GCM coupled to mixed layer ocean. It is used to investigate the climate response to a doubling of the CO₂ concentration together with the direct effect of scattering by sulphate aerosols. As expected, the aerosols offset some of the greenhouse gas (GHG) warming; the global annual mean screen temperature change due to doubled CO₂ is 3.4 °C in this model and this is reduced to 2.7 °C when an estimate of the direct effect of anthropogenic sulphate aerosols is included. The pattern of climate response to the comparatively localized aerosol forcing is not itself localized, and it bears a striking resemblance to the response pattern that arises from the globally distributed change in GHG forcing. This “non-local” response to “localized” forcing indicates that the pattern of climate response is determined, to first order, by the overall magnitude of the change in forcing rather than its detailed nature or structure. Feedback processes operating in the system apparently determine this pattern by locally amplifying and suppressing the response to the magnitude of the change in forcing. The influence of the location of the change in forcing is relatively small. These “non-local” and “local” effects of aerosol forcing are characterized and displayed and some of their consequences discussed. Effects on the moisture budget and on the energetics of the global climate are also examined. Received: 10 June 1997 / Accepted: 8 January 1998     

Article 2 of the UNFCCC: Historical Origins,Recent Interpretations

Article 2 of the UN Framework Convention on Climate Change (UNFCCC), which states the treaty's long-term objective, is the subject of a growing literature that examines means to interpret and implement this provision. Here we provide context for these studies by exploring the intertwined scientific, legal, economic, and political history of Article 2. We review proposed definitions for “dangerous anthropogenic interference” and frameworks that have been proposed for implementing these definitions. Specific examples of dangerous climate changes suggest limits on global warming ranging from 1 to 4 ^∘C and on concentrations ranging from 450 to 700 ppm CO₂ equivalents. The implications of Article 2 for near term restrictions on greenhouse-gas emissions, e.g., the Kyoto Protocol, are also discussed.     

Effects of Greenhouse Gas Emissions on World Agriculture, Food Consumption, and Economic Welfare

Because of many uncertainties, quantitative estimates of agriculturally related economic impacts of greenhouse gas emissions are often given low confidence. A major source of uncertainty is our inability to accurately project future changes in economic activity, emissions, and climate. This paper focuses on two issues. First, to what extent do variable projections of climate generate uncertainty in agriculturally related economic impacts? Second, to what extent do agriculturally related economic impacts of greenhouse gas emissions depend on economic conditions at the time of impacts? Results indicate that uncertainty due to variable projections of climate is fairly large for most of the economic effects evaluated in this analysis. Results also indicate that economic conditions at the time of impact influence the direction and size of as well as the confidence in the economic effects of identical projections of greenhouse gas impacts. The economic variable that behaves most consistently in this analysis is world crop production. Increases in mean global temperature, for example, cause world crop production to decrease on average under both 1990 and improved economic conditions and in both instances the confidence with respect to variable projections of climate is medium (e.g.,67%) or greater. In addition and as expected, CO₂ fertilization causesworld crop production to increase on average under 1990 and improved economic conditions. These results suggest that crop production may be a fairly robust indicator of the potential impacts of greenhouse gas emissions.A somewhat unexpected finding is that improved economic conditions are not necessarily a panacea to potential greenhouse-gas-induced damages, particularly at the region level. In fact, in some regions, impacts of climate change or CO₂ fertilization that are beneficial undercurrent economic conditions may be detrimental under improved economic conditions (relative to the new economic base). Australia plus New Zealand suffer from this effect in this analysis because under improved economic conditions they are assumed to obtain a relatively large share of income from agricultural exports. When the climate-change and CO₂-fertilization scenariosin this analysis are also included, agricultural exports from Australia plus New Zealand decline on average. The resultant declines in agricultural income in Australia plus New Zealand are too large to be completely offset by rising incomes in other sectors. This indicates that regions that rely on agricultural exports for relatively large shares of their income may be vulnerable not only to direct climate-induced agricultural damages, but also to positive impacts induced by greenhouse gas emissions elsewhere.