Climate warming skeptics: Is the research too political?

Some say findings of human-caused global warming say more about politics than about science.

from the October 4, 2007 edition

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'We can't ignore anything'

"The thing about the IPCC report which is not adequately appreciated by many is how rigorous and comprehensive the overall process is," says Kevin Trenberth, head of the National Center for Atmospheric Research's climate analysis section and a coordinating lead author on one chapter of the IPCC report. "We have to weigh all the evidence, but we can't ignore anything."

The IPCC itself does not conduct research but calls on a diverse group of scientists from around the world to review existing research . For example, Dr. Trenberth's group, Working Group I, had 152 lead authors. Some 25 percent were within a decade of having received their PhDs; 75 percent had not been a lead author on any previous IPCC report. And 35 percent hail from non-First World nations. The authors were nominated for participation by their own governments.

The scientist-authors pen a first draft of their findings, which is then sent to other experts in the field for review. Another draft is generated that receives comments from anyone who requests a copy. Review editors who operate independently of the authors ensure that every comment is logged and, if deemed relevant, responded to.

Yet another draft is generated and more reviewers, including governments, weigh in. Each country then solicits reviews nationally. In the United States, the government posted the draft on a website and invited comments from the public.

Some comments couldn't be included because they referred to research published too late to include, says Richard Somerville, a coordinating lead author in Working Group I, in an e-mail. "And we got a certain amount of pure nonsense. But if we rejected a comment, our reasons are written down and [are] public."

Working Group I received some 30,000 direct comments.

Conspiracy unlikely among so many

"If there was going to be a conspiracy among scientists, I can't imagine how you'd manage it," says Martin Manning, director of the IPCC Working Group I Support Unit. "Conspiracy theories run into credibility problems if you start to explore how it would work and how you'd have to make it happen."

Even so-called climate skeptics recognize the report's comprehensiveness. "Nobody could ever imagine 2,500 scientists ever agreeing on everything," says Dr. Christy. He calls the report "a good distillation."

Dr. Singer, also a skeptic, calls the full report "a very useful document." He reserves his stronger criticism for the Summary for Policymakers, a document all government delegations must unanimously approve.

"The summary is basically a political document," Singer argues. He points to wrangling over the Working Group I summary. China asked that the word "very" be removed from the text stating that observed warming was "very likely" due to human-emitted greenhouse gases.

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