Push to Oversimplify at Climate Panel

The group expressed 'regret' last month for an erroneous projection in its influential 2007 climate report that the Himalayan glaciers could melt by 2035.

In the next few days, the world's leading authority on global warming plans to roll out a strategy to tackle a tough problem: restoring its own bruised reputation.

A months-long crisis at the Intergovernmental Panel on Climate Change has upended the world's perception of global warming, after hacked emails and other disclosures revealed deep divisions among scientists working with the United Nation-sponsored group. That has raised questions about the panel's objectivity in assessing one of today's most hotly debated scientific fields.

The problem stems from the IPCC's thorny mission: Take sophisticated and sometimes inconclusive science, and boil it down to usable advice for lawmakers. To meet that goal, scientists working with the IPCC say they sometimes faced institutional bias toward oversimplification, a Wall Street Journal examination shows.

Richard Alley, a geoscientist who helped write the IPCC's latest report, issued in 2007, described a trip that summer to Greenland's ice sheet with senators who urged him to be as specific as possible about the potential for sea-level rise. The point many of them made, he said: Give more explicit advice—because, if the sea rises, "the levee has to be built some height."

The tension within the IPCC stretches back a decade or more, according to interviews with scientists and a review of hundreds of IPCC documents and emails. It has complicated the panel's work on matters ranging from the study of tree rings to the proper use of massively complex climate computer models.

Rajendra Pachauri

The IPCC has faced withering criticism. Emails hacked from a U.K. climate lab and posted online late last year appear to show scientists trying to squelch researchers who disagreed with their conclusion that humans are largely responsible for climate change. And last month, the IPCC admitted its celebrated 2007 report contained an error: a false claim that Himalayan glaciers could melt by 2035. The IPCC report got the date from a World Wildlife Fund report.

Even some who agree with the IPCC conclusion that humans are significantly contributing to climate change say the IPCC has morphed from a scientific analyst to a political actor. "It's very much an advocacy organization that's couched in the role of advice," says Roger Pielke, a University of Colorado political scientist. He says many IPCC participants want "to compel action" instead of "just summarizing science."

To restore its credibility, the IPCC will focus on enforcing rules already on the books, IPCC Chairman Rajendra Pachauri and other officials said in interviews. Scientific claims must be checked with several experts before being published. IPCC reports must reflect disagreements when consensus can't be reached. And people who write reports must refrain from advocating specific environmental actions—a political line the IPCC isn't supposed to cross. Read more.