By Juliet Eilperin and David A. Fahrenthold
Washington Post Staff Writer
Monday, February 15, 2010; A01
With its 2007 report declaring that the "warming of the climate system is unequivocal," the U.N. Intergovernmental Panel on Climate Change won a Nobel Prize -- and a new degree of public trust in the controversial science of global warming.
But recent revelations about flaws in that seminal report, ranging from typos in key dates to sloppy sourcing, are undermining confidence not only in the panel's work but also in projections about climate change. Scientists who have pointed out problems in the report say the panel's methods and mistakes -- including admitting Saturday that it had overstated how much of the Netherlands was below sea level -- give doubters an opening.
It wasn't the first one. There is still a scientific consensus that humans are causing climate change. But in the past year, a cache of stolen e-mails, revealing that prominent climate scientists sought to prevent the publication of works by their detractors, has sullied their image as impartial academics. The errors in the U.N. report -- a document intended to be the last nail in the coffin of climate doubt -- are a serious problem that could end up forcing environmentalists to focus more on the old question of proving that climate change is a threat, instead of the new question of how to stop it.
Two Republican senators who have long opposed a cap on carbon emissions, James M. Inhofe (Okla.) and John Barrasso (Wyo.), are citing the errors as further reasons to block mandatory limits on greenhouse gas emissions. Last week, Barrasso called for an independent probe into the IPCC, suggesting that the United States should halt any action on climate until it verifies the panel's scientific conclusions.
Inhofe said Thursday in the Senate that the Environmental Protection Agency's efforts to curb greenhouse gases should be reexamined, since the U.N. panel's conclusions influenced the agency's finding that climate change poses a public threat. "The ramifications of the IPCC spread far and wide, most notably to the Environmental Protection Agency's finding that greenhouse gases from mobile sources endanger public health and welfare," Inhofe said. On Friday, a coalition of conservative groups filed a petition to overturn the EPA's finding on the same grounds.
"There is a sense that something's rotten in the state of the IPCC," said Richard H. Moss, a senior scientist at the Joint Global Change Research Institute at the University of Maryland, who has worked with the panel since 1993. "It's just wildly exaggerated. But we need to take a look and see if something needs to be improved."
The IPCC climate assessments are, by any standard, a massive undertaking. Thousands of scientists across the globe volunteer to evaluate tens of thousands of academic documents and translate them into plain-English reports that policymakers can understand.
Climate researchers say the errors do not disprove the U.N. panel's central conclusion: Climate change is happening, and humans are causing it. Some researchers said the U.N. panel's attitude -- appearing to promise that its results were infallible, and reacting slowly to evidence that they were not -- could undermine the rest of its work.
"What's happened here is that there's an industry of climate-change denialists who are trying to make it seem as though you can't trust anything that is between the covers" of the panel's report, said Jeffrey Kargel, a professor at the University of Arizona who studies glaciers. "It's really heartbreaking to see this happen, and to see that the IPCC left themselves open" to being attacked.
Kargel said he noticed an error in the report of the IPCC's second working group, a research unit, in 2007. The report said huge glaciers in the Himalayan mountains might disappear by 2035. Some glaciers are melting, but they are too enormous to disappear that quickly: "It's physically impossible to kill the ice that fast," Kargel said.
He said colleagues regarded the error as too ridiculous to fuss about until recently. Last month, the journal Science printed a letter to the editor that traced the origins of the mistaken data: The U.N. panel seemed to have quoted an activist group's report, not a peer-reviewed study. And, in citing another source, it appeared to have committed a serious typo: The year 2350 had become 2035.
Another line that has sparked scrutiny reads, "Up to 40 percent of the Amazonian forests could react drastically to even a slight reduction in precipitation," and links to a report co-written by the World Wildlife Fund. The analysis cited key work by Woods Hole Research Center senior scientist Daniel C. Nepstad, but the link to an advocacy group instead of a peer-reviewed paper infuriated conservatives.
"The underlying science is certainly there, but the citation process the IPCC went through is sloppy. There's no other word for it," said Doug Boucher, director of the Tropical Forest and Climate Initiative at the Union of Concerned Scientists.
The IPCC did not respond to requests for comment.
Roger Pielke Jr., a political scientist and environmental studies professor at the University of Colorado, said that the U.N. panel could hurt its own public standing by not admitting how it exaggerated certain climate risks or connections, such as linking higher insurance payouts to rising temperatures when other factors are driving this trend.
"The idea that the IPCC can or should strive to be infallible is really not helpful," Pielke said. "When errors and mistakes are inevitably found, the fall is that much further. . . . There's a real risk that the public perception could swing [toward greater disbelief in climate science]. Even though the reality is that the science -- the underlying science -- hasn't changed."
The error about the Netherlands was in a background note in the 2007 report that said 55 percent of the country lay below sea level, but that figure included areas that were actually above sea level and prone to flooding.
U.N. Foundation President Timothy E. Wirth, whose nonprofit group has highlighted the work of the IPCC, said that the pirated e-mails gave "an opening" to attack climate science and that the scientific work "has to be defended just like evolution has to be defended."
It is unclear whether the controversy will hamper passage of a bill to cap U.S. greenhouse gas emissions, which has stalled in the Senate. Paul W. Bledsoe, of the bipartisan National Commission on Energy Policy, said that if people want to know why the "bill is having a hard time in the Senate, I would rank [concern about climate science] lower than the economy and the financial meltdown."
Scientists are debating whether they need to revamp the IPCC process or scrap it. The journal Nature published an opinion section Thursday in which several researchers floated ideas on how to change the U.N. panel, along with a piece written by Moss and others showing how scientists could increase collaboration across disciplines to produce more accurate climate projections more quickly.
And Christopher Field -- co-chair of the second working group for the IPCC's next assessment -- said the panel needs to improve its fact-checking, even if it means enlisting report contributors' students to help do the job.
"My goal is to produce a report that's 100 percent error-free, to the maximum extent possible," he said. "The fact that the IPCC runs on volunteer labor makes it a challenge, but it's too important a challenge to ignore."