Here are interviews with leading proponents and skeptics of global warming's threat. These interviews were conducted by FRONTLINE/NOVA producer Jon Palfreman.

		A climate modeler with the Scripps Institution of Oceanography, he has written and lectured extensively about climate change. His interview offers an easy-to-follow guide to what science does and doesn't know about climate past, present and future. It also deals with the reliability of computer climate models, why understanding clouds is a top research priority for climatologists, and what's fueling the heated, polarized debate over global warming.
		A professor of biological sciences at Stanford University, he has been arguing the dangers of human-induced climate change for over two decades. In this interview, he outlines the 'best guess' global warming scenario which has been arrived at by the bulk of scientists. He also explains how the challenge of finding new carbon free energy sources can be met, and why the 1997 Kyoto Protocol on reducing greenhouse gas emissions was a crucial event for the world, even if it is not ratified by the United States.
		He is an atmospheric physicist at George Mason University and founder of the Science and Environmental Policy Project, a think tank on climate and environmental issues. Singer has been a leading skeptic of the scientific consensus on global warming. He points out that the scenarios are alarmist, computer models reflect real gaps in climate knowledge, and future warming will be inconsequential or modest at most.
		He is an influential climatologist and senior scientist at the National Center for Atmospheric Research. Wigley was part of a team whose analyses of the earth's average surface temperature, and how it has risen, has become the data most cited by climate experts. He also was a lead author of the landmark 1995 Intergovernmental Panel on Climate Change (IPCC) report which said that human activity is a likely cause of the warming of the earth's atmosphere. In this interview he summarizes the evidence pointing to the human factor in global warming, addresses skeptics' criticisms about this evidence, and explains how societies are vulnerable to even relatively small changes in climate.
		He is President of Western Fuels Association, Inc. and maintains that many scientists, politicians and environmental groups have greatly overstated the threat and consequences of climate change. He argues that inexpensive fossil fuels such as coal are an essential component of U.S. economic success and cutting back fossil fuel use would seriously affect the world's social and economic progress.
		A co-director of the MIT Joint Program on the Science and Policy of Global Change, he explains in this interview why global warming is so very different from previous international issues which threatened the world's environment or security. He also discusses the political challenges in cutting fossil fuel use in the future and what the impact would be on developed and developing nations.