Abstract. Over 250 respondents – graduate students in law and public policy – assessed the risks of climate change and valued climate-change mitigation policies. Many aspects of their behavior were consistent with rational behavior. For example, respondents successfully estimated distributions of temperature increases in Boston by 2100. The median value of best estimates was 1–3 degrees Fahrenheit. In addition, people with higher risk estimates, whether for temperature or related risks (e.g., hurricane intensities) offered more to avoid warming. Median willingness to pay (WTP) to avoid global warming was $0.50/gallon, and 3 % of income. And important scope tests (e.g., respondents paid more for bigger accomplishments) were passed. However, significant behavioral propensities also emerged. For example, accessibility of neutral information on global warming boosted risk estimates. Warming projections correlated with estimates for unrelated risks, such as earthquakes and heart attacks. The implied WTP for avoidance was much greater when asked as a percent of income than as a gas tax, a percent thinking bias. Home team betting showed itself; individuals predicting a Bush victory predicted smaller temperature increases. In the climate-change arena, behavioral decision tendencies are like a fun-house mirror: They magnify some estimates and shrink others, but the contours of rational decision remain recognizable. 1.

Although, there is a growing literature on scientific estimates and regulatory instruments for international efforts to control greenhouse gas (GHG) emissions, the underlying political collective action processes have been neglected. We focus on the impact of uncertainty in assessing the benefits and costs of global warming regulation on constituencies and politicians in the bargaining countries. Uncertainty arises due to basic information problems about the net effects of global warming, its regulation, and compliance by sovereign countries. We outline a two-stage analytical framework that describes the positions taken by representatives of negotiating countries and the internal public choice tradeoffs facing politicians when constituents are faced with differential and uncertain effects. We apply the framework to the Law of the Sea Treaty of 1982 (LOS), the Montreal Protocol to Control Substances that Damage the Ozone Layer of 1987, and the Kyoto Protocol of 1997. Additional information will reduce uncertainty over time, and until uncertainty is lowered we conclude that limited regulatory efforts are most likely to generate internal political support within negotiating countries for international collective action.

Warwick J. McKibbin is a professor of international economics at the Australian National University as well as a non-resident senior fellow at the Brookings Institution. Peter J. Wilcoxen is an associate professor of economics and public administration at Syracuse University as well as a non-resident senior fellow at the Brookings Institution. Brookings Discussion Papers in International Economics are circulated to stimulate discussion and critical comment. They have no been exposed to the regular Brookings prepublication review and editorial process. References in publications to this material, other than acknowledgment by a writer who has had access to it, should be cleared with

International trade in permits lowers the global cost of abatement, and provides incentives for developing countries to accept commitments. Trade in emissions rights is greatly to be preferred to trade in offset credits, which should be restricted. A global agreement on minimum commitments to investment in lowemissions new technologies is required to ensure an adequate level of funding of research, development and commercialisation. Australia’s commitment to support of research, development and commercialisation of low-emissions technology would be about $2.8 billion. An International Adaptation Assistance Commitment would provide new adaptation assistance to developing countries that join the mitigation effort. Early sectoral agreements would seek to ensure that the main tradeexposed, emissions-intensive industries face comparable carbon prices across the world, including metals and international civil aviation and shipping.

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