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Page 68 8 Findings and Conclusions This study reviews current knowledge about greenhouse warming and examines a wide variety of potential responses. The panel finds that, even given the considerable uncertainties in our knowledge of the relevant phenomena, greenhouse warming poses a potential threat sufficient to merit prompt responses. People in this country could probably adapt to the likely changes associated with greenhouse warming. The costs, however, could be substantial. Investment in mitigation measures acts as insurance protection against the great uncertainties and the possibility of dramatic surprises. In addition, the panel believes that substantial mitigation can be accomplished at modest cost. In other words, insurance is cheap. These responses, however, must be based on consideration of the uncertainties, costs of actions and inaction, and other factors. The panel believes they should be based on the approach outlined in Chapter 4. Actions that would help people and natural systems adapt to climate change are described in Chapter 5. Actions to mitigate greenhouse warming are described in Chapter 6. The findings and conclusions presented here draw on the detailed assessments performed by the other three panels contributing to this study: the Effects Panel (Part Two), the Mitigation Panel (Part Three), and the Adaptation Panel (Part Four). The Synthesis Panel, however, considered additional materials in its deliberations and in the preparation of this report. These include, for example, the reports of the three IPCC working groups, the conference statement from the Second World Climate Conference, statements from other international meetings, publications of the national laboratories and other research organizations in the United States, and documents prepared in other countries. The findings and conclusions of this
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Page 69 panel reflect additional analysis, deliberation, and judgment beyond those of the other panels contributing to this study. Policy Considerations The phenomenon of greenhouse warming is complex, and so are the possible responses to it. First, the extent, timing, and variation of future warming and its likely impacts need to be assessed. Second, both the cost and the effectiveness of options to slow greenhouse warming must be estimated and compared to the costs of postponing action. Third, the possible advantages and disadvantages of these actions need to be evaluated in light of the extent to which people, plants, and animals are likely to adjust by themselves or with assistance to changes in the climate. Fourth, the policymaker needs to evaluate these actions in comparison to other ways resources might be used. Before acting, we need to be confident that expenditures to slow climate change make sense. Fifth, decision makers will judge all these factors in a broader context. Responses to greenhouse warming will be determined by people worried about economic growth, food supply, energy availability, national security, and a host of other problems. Many responses appear to produce sizable benefits with regard to other goals, such as reducing air pollution. This study makes no attempt to assess these additional dividends. Instead, it focuses on response to greenhouse warming as such. Capacities of Industrialized and Developing Countries Different countries have quite different capacities to respond to change. Poverty, in particular, makes people vulnerable to change and substantially reduces their flexibility in responding to change. Countries with low percapita income face difficult trade-offs between stimulating economic development and alleviating environmental problems. These countries, which already have difficulty coping with environmental stresses today, will be even more sorely pressed when confronted by climate change. This report examines response to greenhouse warming in the United States, a country richly endowed with natural and human resources, and one benefiting from a geography that encompasses many climate zones. Compared to many other countries, the United States is well situated to respond to greenhouse warming. This panel does not attempt to view greenhouse warming from the perspective of a country less well endowed. Of course, greenhouse warming is a global phenomenon, and many global aspects must be included in any analysis. Nevertheless, most of the data utilized in this study to evaluate
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Page 70 mitigation and adaptation options relate to the United States. A more comprehensive examination must wait for future studies. Taxes and Incentives Decisions about energy use and other activities that emit greenhouse gases are made daily, even hourly, by 250 million people in the United States in many different areas from transportation to hair drying. Experience here and abroad has shown the inducements of prices and taxes to be a sure way to transmit government policies to decentralized decision makers. Achieving significant reductions in greenhouse gas emissions, however, could involve considerable sacrifice and economic disruption. There are advantages of market-incentive approaches, but they are not universal. For particular technologies, like the chlorofluorocarbons (CFCs), it may be quicker to use direct regulatory interventions such as emissions limits or caps, although buttressing these with taxes can ensure that the regulations are enforced. An alternative to taxes that has been suggested, and endorsed by several foreign governments and the United States in the Clean Air Act, is establishing emission limits. While this approach seems reasonable on the surface, it has significant shortcomings in implementation. The major defect with regulatory actions such as emission limits is that there is no easy way that the government can directly control emissions from so many different and separate sources. However, regulation as a technology-forcing mechanism has contributed to reducing emissions of key air pollutants in the United States. It other areas it has been less successful. Taxes and regulations can discourage or prevent people from taking actions that would increase greenhouse gas emissions; incentives of various kinds can encourage them to act in ways that reduce emissions. If interventions are needed, this panel believes that, in general, incentive-type measures are preferable. Fundamental and Applied Research Research is inexpensive in comparison with many other policy options that could make a difference in greenhouse warming. The federal research budget on topics related to global climate change is a little more than $1 billion for fiscal year 1991, which is small in comparison to the expected impact or costs of climate change. Although these funds have been identified as applying to greenhouse warming research, some of them contribute to other objectives as well. Policy should be designed and executed in ways that increase our understanding of the way human activity affects greenhouse warming.
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Page 71 Research on the actual impacts of climate change may identify vulnerabilities and highlight areas for policy action. Every year there are droughts, heat waves, severe storms, and other such phenomena. Understanding how economies and communities of plants and animals are affected by extreme climate events, and whether those responses are changing over time, could provide important guidance for policy choices. Better understanding of how biological communities function as both sources and sinks of greenhouse gases, especially CO2, might also help anticipate the consequences of greenhouse warming. More detailed knowledge about phenomena affecting radiative forcing, such as cloud physics and chemistry, or of key mechanisms in the global climate system, such as ocean currents and heat transfers, could help identify where actions might have greatest leverage. Research satellites capable of measuring the energy balance of the earth are necessary, as is maintaining thermometer measurement networks. Most research up to now has emphasized climatological issues. The global climate change budget in the United States is about 95 percent on the physical phenomena of atmosphere, oceans, and so on and 5 percent on mitigation, adaptation, and impacts. We need to know more about the social and economic processes generating greenhouse gas emissions and about the costs of mitigating these emissions, especially in the energy sector. We need reviews and assessments of policy options to slow climate change, and improvements in the data base for understanding economic and environmental trends relating to global change. Because greenhouse warming is a global problem encompassing a wide range of areas, it will be important to establish programs that are interdisciplinary and examine developing countries as well as high-income countries like the United States. A Proposed Framework for Responding to the Threat of Greenhouse Warming The analyses performed for this study show that the United States should be able to adapt to the changes in climate expected to accompany greenhouse warming. They have also identified a number of options that could slow or offset the buildup of greenhouse gases. Other options could help position us to ease future adaptations to the consequences of greenhouse warming. The fact that people can adapt, or even that they are likely to do so, does not mean that the best policy is to wait for greenhouse warming to occur and let them adapt. Waiting and adapting may sacrifice overall economic improvement in the long run. The panel has sorted response policies into five categories: (1) reducing or offsetting greenhouse gas emissions, (2) enhancing adaptation to greenhouse warming, (3) improving knowledge for future decisions, (4) evaluating
Page 72 geoengineering options, and (5) exercising international leadership. The recommended options in each category are described in Chapter 9. General Conclusions In conducting this study, the panel first established the approach and framework described in Chapter 4. The information and data summarized in Chapters 5 and 6 were then gathered and analyzed. On this basis, the Synthesis Panel reached the collective judgment that the United States should undertake not only several actions that satisfy multiple goals but also several whose costs are justified mainly by countering or adapting to greenhouse warming. The panel believes that a systematic implementation of the complete set of low-cost options described in Chapter 9 is appropriate. The panel concludes that options requiring great expenses are not justified at this time.
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