This paper surveys and interprets the attitudes of scientists to the use of flux adjustments in climate projections with coupled Atmosphere Ocean General Circulation Models. The survey is based largely on the responses of 19 climate modellers to several questions and a discussion document circulated in 1995. We interpret the responses in terms of the following factors: the implicit assumptions which scientists hold about how the environmental policy process deals with scientific uncertainty over human-related global warming; the different scientific styles that exist in climate research; and the influence of organisations, institutions, and policy upon research agendas. We find evidence that scientists' perceptions of the policy process do play a role in shaping their scientific practices. In particular, many of our respondents expressed a preference for keeping discussion of the issue of flux adjustments within the climate modeling community, apparently fearing that climate contrarians would exploit the issue in the public domain. While this may be true, we point to the risk that such an approach may backfire. We also identify assumptions and cultural commitments lying at a deeper level which play at least as important a role as perceptions of the policy process in shaping scientific practices. This leads us to identify two groups of scientists, 'pragmatists' and 'purists,' who have different implicit standards for model adequacy, and correspondingly are or are not willing to use flux adjustments. / Includes bibliographical references. / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/) / Funded by the UK's Economic and Social Research Council as part of the "Science, Culture and the Enviroment" program at Lancaster University, UK.

Different atmosphere-ocean general circulation models produce significantly different projections of climate change in response to increases in greenhouse gases and aerosol concentrations in the atmosphere. The main reasons for this disagreement are differences in the sensitivities of the models to external radiative forcing and differences in their rates of heat uptake by the deep ocean. In this study, these properties are constrained by comparing radiosonde-based observations of temperature trends in the free troposphere and lower stratosphere with corresponding simulations of a fast, flexible climate model, using techniques based on optimal fingerprinting. Parameter choices corresponding either to low sensitivity, or to high sensitivity combined with slow oceanic heat uptake are rejected. Nevertheless, a broad range of acceptable model characteristics remains, such that climate change projections from any single model should be treated as only one of a range of possibilities. / Includes bibliographical references (p. 10-11). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

Global climate change is on the political agenda primarily as a result of science and the warnings of the scientific community, and is commonly seen as a quintessentially scientific matter. However, the development of policy on this issue in the U.S. today does not turn on the scientific evidence. Rather, policy is determined by the political and economic forces involved, with reference to the science only to support positions reached on other grounds. The reasons relate primarily to the uncertainty in the evidence, the structure and politics of the government, the economic costs and impact of change and of policies to reduce greenhouse gases, the international structure in which the issue is being confronted, the role of the media, and the effects of partisan politics. In this situation, the scientific and engineering communities (including social scientists and especially economists) have a major responsibility to maintain their professional values and objectivity so dominated at the moment by other pressures. Only that way can they retain the public trust that will be necessary if and when costly policy measures must be undertaken. / Includes bibliographical references. / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

The Kyoto Protocol is an international agreement aimed at limiting emissions of several greenhouse gases (GHGs; specifically: CO2, CH4, N2O, PFCs, HFCs, and SF6), and allows credit for approved sinks for CO2. It does not include consideration of several other trace atmospheric constituents that have important indirect effects on the radiative budget of the atmosphere. Here we show that inclusion of other GHGs and CO2 sinks greatly reduces the cost of achieving CO2 emissions reductions specified under the agreement. The Kyoto Protocol extrapolated to 2100 reduces predicted warming by only about 17%. The errors caused by simulating other GHGs with scaled amounts of CO2 on atmospheric composition, climate, and ecosystems are small. Larger errors come from failure to account for interactive and climatic effects of gases that affect atmospheric composition but are not included in the protocol (CO, NOx, and SOx). Over the period to 2100, the Global Warming Potential (GWP) indices based on a 100-year time horizon as specified in the protocol appear to be an adequate representation of trace gas climatic effects. The principal reason for the success of this simplified GWP approach in our calculations is that the mix of gas emissions resulting from a carbon-only rather than a multi-gas control strategy does not change by a large amount. / Includes bibliographical references (p. 13-14). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

Climate policy regarding perfluorocarbons (PFCs) may have a significant influence on investment decisions in the production of primary aluminum. This work demonstrates an integrated analysis of the effectiveness and likely economic consequences of different climate policy options. In our study we first compare atmospheric observations to the available estimates of PFC emissions for the baseline years 1990 and 1995. We then present projections for regional emissions of PFCs from the aluminum industry using the MIT Emissions Projection and Policy Analysis model under different policy scenarios. Abatement costs for emissions of PFCs and CO2 are compared in the context of the Kyoto Protocol. / Includes bibliographical references (p. 17-18). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

The current misplaced focus on short-term climate policies is a product both of domestic political exigencies and badly flawed technical analyses. A prime example of the latter is a recent U.S. Department of Energy study, prepared by five national laboratories. The 5-Labs study assumes —- incorrectly —- that technical solutions are readily at hand. Worse, advocates of short-term emissions targets under the Framework Convention on Climate Change are using this study to justify the subsidy of existing energy technologies —- diverting resources from the effective long-term technology response that will be needed if the climate picture darkens. / Includes bibliographical references (p. 15-16). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

There are many obstacles to the development of an international CO₂ emissions trading system, but the biggest is a feature that is often assumed: the existence of a single national system. Once a national system is in place, an international system will develop naturally more as a matter of self-interested trade than as international agreement. Meeting the Kyoto targets will create a scarcity; and the scarcity requires that use and the associated rent be allocated somehow. This allocation — deciding who gets what — is a familiar problem and the largest impediment to the creation of a national system, and thus of an international regime of CO₂ emissions trading. The paper reviews the various instruments by which such the Kyoto target might be met from the standpoint of the allocation of the scarce use and the associated rent. In particular, the paper emphasizes that existing users will largely continue to use the scarce resource and that they now actively exercise the incipient right to the proposed scarcity. Creation of the scarcity and the allocation of rights raise fundamental issues of equity that lie pre-eminently in the political realm. The author observes that the creation of the scarcity and the allocation of rights are fused and that agreement on one will occur only as there is agreement on the other. Nevertheless, such problems have been solved before — for land and for SO₂ permits — although in both cases the conditions were easier than what is now proposed for CO₂. An international CO₂ trading system will develop from a national allowance system for the same reasons that trading can be expected to occur domestically. However, the unavoidable requirement of certification and verification will impede access to non-Annex B sources of emission reduction, and at the same time encourage countries with such sources to accept Annex B limits. The negotiation of such limits raises the same problems of allocation as faced at the national level, only on a global scale; and there is even less agreement here. Nevertheless, the discussion on global allocation will not begin in earnest until a national system creates the trade opportunities that will make an Annex B limit worth pursuing. The development of an international system for CO₂ emissions trading should not be expected to be either quick or easy, but to occur only by accretion and mostly as a matter of self-interested trade. / Includes bibliographical references (p. 12). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

This paper examines the effect of the Kyoto Protocol on developing economies using marginal abatement curves generated by MIT's Emissions Prediction and Policy Assessment model (EPPA). In particular, the paper addresses how developing countries are affected by the scope of CO2 emissions trading, by various limitations that Annex I countries might place on emissions trading, by the nature of the Clean Development Mechanism, and by changes in the international trade flows in conventional goods and services. In general, it is found that developing countries benefit from emissions trading, both from the new export opportunities and by the lesser distortion of Annex I economies. This effect is particularly pronounced for energy exporting countries since Annex I countries are able to substitute cheaper reductions of coal emissions in developing countries for more expensive reductions of oil emissions within Annex I. The paper also highlights the implications of the apparent inelastic demand for tradable permits from non-Annex I countries and the conflict between revenue maximization and other goals assigned to the Clean Development Mechanism. / Includes bibliographical references (p. 22-23). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

Marginal abatement curves (MACs) are often used heuristically to demonstrate the advantages of emissions trading. In this paper, the authors derive MACs from EPPA, the MIT Joint Program's computable general equilibrium model of global economic activity, energy use and CO₂ emissions, to analyze the benefits of emissions trading in achieving the emission reduction targets implied by the Kyoto Protocol. The magnitude and distribution of the gains from emissions trading are examined for both an Annex B market and for full global trading, as well as the effects of import limitations, non-competitive behavior, and less than fully efficient supply. In general, trading benefits all parties at least some, and from a global standpoint, the gains from trading are greater, the wider and less constrained is the market. The distribution of the gains from trading is, however, highly skewed in favor of those who would face the highest costs in the absence of emissions trading. / Includes bibliographical references. / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)

In this paper, we present an integrated framework for structuring and evaluating sequential greenhouse gas abatement policies under uncertainty. The analysis integrates information concerning the magnitude, timing, and impacts of climate change with data on the likely effectiveness and cost of possible response options, using reduced-scale representations of the global climate system drawn from the MIT Integrated Global System Model. To illustrate the method, we explore emissions control policies of the form considered under the United Nations Framework Convention on Climate Change. / Includes bibliographical references (p. 27-28). / Abstract in HTML and technical report in HTML and PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/)