Climate Change: Expert Opinion on the Economics of Policy Options to Address Climate Change

摘要

Elevated levels of greenhouse gases in the atmosphere and the resulting effects on the earth's climate could have significant environmental and economic impacts in the United States and internationally. Potential impacts include rising sea levels and a shift in the intensity and frequency of floods and storms. Proposed responses to climate change include adapting to the possible impacts by planning and improving protective infrastructure, and reducing greenhouse gas emissions directly through regulation or the promotion of low-emissions technologies. Because most U.S. emissions stem from the combustion of fossil fuels such as coal, oil, and natural gas, much of this report centers on the effect emissions regulation could have on the economy. In this context, GAO was asked to elicit the opinions of experts on (1) actions the Congress might consider to address climate change and what is known about the potential benefits, costs, and uncertainties of these actions and (2) the key strengths and limitations of policies or actions to address climate change. GAO worked with the National Academy of Sciences to identify a panel of noted economists with expertise in analyzing the economic impacts of climate change policies and gathered their opinions through iterative, Web-based questionnaires. The findings reported here represent the views of the 18 economists who responded to both questionnaires. All of the panelists agreed that the Congress should consider using a market-based mechanism to establish a price on greenhouse gas emissions, and 14 of the 18 panelists recommended additional actions as part of a portfolio to address climate change, such as investment in research and development of low-emissions technologies. To establish a price on emissions, most of the panelists preferred either a tax on emissions or a hybrid policy that incorporates features of both a tax and a cap-and-trade program. Under the cap-and-trade system, the market would determine the price of emissions. A hybrid system differs from a traditional cap-and-trade system in that the government would cap emissions, but could sell additional emissions permits if the permit price rose above a predetermined level. The panelists rated cost effectiveness as the most important criterion for evaluating various policy options.