The Scientific Consensus

The U.S. Administration states that the science is "clear and compelling," based on the supposed consensus of 2,000 (and sometimes 2,500) scientists that "the balance of evidence...suggests a discernible human influence on global climate." This statement comes from the 'Summary for Policymakers' of the UN Intergovernmental Panel on Climate Change (IPCC).

The IPCC published three reports of published research on climate change in 1995 on: science; impacts, adaptation and mitigation; and economics. The contributors and reviewers of all three volumes total about 2,100, relatively few of which are specialists in atmospheric physics. Most are economists, social scientists, policy experts, and government functionaries.

Chapter Eight of the report, "Detection of Climate Change and Attribution of Causes" which provided the background for the "discernible impact' statement, had four lead authors and 32 contributors (not 2,000). After it had been peer-reviewed and approved by the contributors, the chapter was modified so as to change the tone, creating considerable controversy.

From this material, the 'Summary for Policymakers' was written. As one of the IPCC lead authors, Keith Shine said, "We produce a draft, and then the policymakers go through it line by line and change the way it is presented... It's peculiar that they have the final say in what goes into a scientists' report."

Robert Reinstein, former chief State Department negotiator on the climate treaty under President Bush, agrees that the wording of the summary was negotiated at length by international delegations. "Because of this," he said, "the summary must be considered purely a political document, not a scientific one."

Ben Santer, one of the lead authors of the controversial Chapter Eight, said, "It's unfortunate that many people read the media hype before they read the chapter. I think the caveats are there. We say quite clearly that few scientists would say the attribution issue was a done deal."

In July 1996, over 100 European and American scientists issued the "Leipzig Declaration," warning that there is still no scientific consensus on the subject of climate change. "On the contrary," the statement says, "most scientists now accept the fact that actual observations from earth satellites show no climate warming whatsoever."