3. The Structure of Government
4. Economic Impacts
5. The United States' Inward Focus
6. The Media
7. Partisan Politics
Climate change is on the international policy agenda primarily because of warnings from scientists. Their forecasts of a potentially dangerous increase in the average global temperature, fortuitously assisted by unusual weather events, have prompted governments to enter into perhaps the most complicated and most significant set of negotiations ever attempted. Key questions - the rapidity of global climate change, its effects on the natural systems on which humans depend, and the options available to lessen or adapt to such change - have energized the scientific and related communities in analyses that are deeply dependent on scientific evidence and research. At both the national and international levels, the policy debate over climate change is unfolding rapidly. But it is also becoming increasingly mired in controversy, and nowhere more so than in the United States. This raises a crucial question: Why is it that this country - the undisputed leader of the world in science and technology - is finding it so difficult to agree on policies to address an ecological threat that, if it materializes, could have catastrophic consequences for itself and the rest of the world? The perhaps surprising answer is that in the U.S. policy process, climate change is not now a scientific issue. Although much of the controversy appears to revolve around scientific principles, political and economic forces actually dominate. In a sense, this is not surprising: in dealing with possible climate change, policymakers, stakeholders, and the public have to confront competing economic interests, significant political change, and such difficult issues as intergenerational equity, international competition, national sovereignty, and the role (and competence) of international institutions. What are the primary factors that determine policy outcomes on this complex subject? Detailing them vividly demonstrates how scientific knowledge interacts with the formulation of policy on a significant issue in the United States. Of the many factors that can affect the role scientific evidence plays in questions of public policy, most important in the case of climate change appear to be: the uncertainty of the scientific evidence; the structure of government; debatable economic assessments; the international framework; the media; and partisan politics. Although they are all significant, the uncertainty of the evidence on this issue permeates all the others.
At its core, the climate change issue hinges on scientific evidence and forecasts. The entire subject of global warming is on the world's agenda because scientists have forecast that such warming will occur if the greenhouse gases produced by humans continue to accumulate as they have since the beginning of the Industrial Revolution. Concerns grew when a series of hot summers in the 1980s and 1990s appeared to the public to confirm these forecasts, and continuing assessments by the Intergovernmental Panel on Climate Change (IPCC) have strengthened the general perception that the phenomenon is real. In fact, the IPCC assessment in 1995 cited the increase in the Earth's mean surface temperature and the changes in the patterns of atmospheric temperatures to justify its assertion (in its summary statement) that "the balance of evidence . . . suggests that there is a discernible human influence on global climate." More recent IPCC findings (2001) suggested with much more stronger force the reality of global warming and highlighted a definite human input in this process, at least to some degree. But the evidence on climate change is not clear-cut. There is considerable uncertainty both about the basic conclusion of a demonstrable anthropogenic "fingerprint" and, at least as important, about the scale...