Global Warming: Is the Science Settled Enough For Policy?

Dr. Steven Schneider


Stephen H. Schneider (born c. 1945) is Professor of Environmental Biology and Global Change (Professor by Courtesy in the Department of Civil and Environmental Engineering) at Stanford University, a Co-Director at the Center for Environment Science and Policy of the Freeman Spogli Institute for International Studies and a Senior Fellow in the Stanford Woods Institute for the Environment. He has served as a consultant to Federal Agencies and/or White House staff in the Nixon, Carter, Reagan, George H. W. Bush, Clinton and George W. Bush administrations.

His research includes modeling of the atmosphere, climate change, and "the relationship of biological systems to global climate change." He has helped draw public attention to the issue of climate change. He is the founder and editor of the journal Climatic Change. He has authored or co-authored over 450 scientific papers, proceedings, legislative testimonies, edited books and book chapters; some 140 book reviews, editorials, published newspaper and magazine interviews and popularizations. He was a Coordinating Lead Author in Working Group II IPCC TAR; and is currently a co-anchor of the Key Vulnerabilities Cross-Cutting Theme for the Fourth Assessment Report (AR4). During the 1980s Schneider emerged as a leading public advocate of sharp reductions of greenhouse gas emissions to combat global warming. In 2007 the IPCC shared the Nobel Peace Prize with former US vice president, Al Gore, "for efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change."


In the Fourth Assessment Report of the UN-sponsored Intergovernmental Panel on Climate Change (which shared the 2007 Nobel Peace Prize), Working Group I states that warming is “unequivocal” and it is “very likely” that human activities are responsible for most of the warming of recent decades. The same report says warming to 2100 is “likely” to be 1.1 – 6.4 degrees C. Working Group II says 1.5 – 2.5 degrees C warming could commit 20-30% of known species to extinction (but only assigns this about a 50% chance). So, what is settled? Some projections are well established, some have competing explanations, yet others are speculative. Thus policy is a risk management judgment, just like most other complex socio-technical systems problems.

The number of people in the world is increasing, and they will undoubtedly demand higher standards of living that likely will be fueled by cheap, available energy sources such as coal for electricity generation and petroleum for gas-consuming large automobiles—sources which emit large amounts of green house gases. There is strong consensus that if this is the case, the carbon dioxide content in the atmosphere will double or triple by 2100. Many potentially serious impacts (although not all are negative) are expected. These impacts will be unevenly distributed with the most severe effects being experienced in poorer, warmer places, high mountains and polar regions or in “hurricane alley.” Local, regional, and international actions to put in place both adaptation and mitigation policies are already beginning and much more could be done if there were political will to substantially reduce the magnitude of the risks.

Dr. Steven Schneider

Dr. Steven Schneider

Willamette University

Dempsey Lecture

900 State Street
Salem Oregon 97301 U.S.A.

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