A federal hurricane research scientist resigned last week from a U.N.-sponsored climate assessment team, saying the group's leader had politicized the process.
Chris Landsea, who works at the National Oceanic and Atmospheric Administration's hurricane research division in Miami, said Monday that he would not contribute to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change's chapter on atmospheric and surface climate conditions because the lead author had told reporters global warming contributed to intense Atlantic hurricanes last year.
In a letter he posted on the Internet, Landsea said there was little evidence to justify Kevin Trenberth's assertion in October that in light of current warming trends, "the North Atlantic hurricane season of 2004 may well be a harbinger of the future."
"It is beyond me why my colleagues would utilize the media to push an unsupported agenda that recent hurricane activity has been due to global warming," he wrote. "My view is that when people identify themselves as being associated with the IPCC and then make pronouncements far outside current scientific understandings that this will harm the credibility of climate change science and will in the longer term diminish our role in public policy."
The spat between Landsea and Trenberth -- who heads the climate analysis section at the private nonprofit National Center for Atmospheric Research in Boulder, Colo. -- underscores a larger battle over what role scientists should play in one of the decade's most contentious environmental debates. Some researchers say they have a duty to express concern about human contributions to climate change, given what is at stake; others say scientists have no right to act as policy advocates.
The IPCC, which has already concluded that human activity accounts for much of the warming the earth has experienced over 50 years, is seeking to evaluate how and why the climate is changing. It will issue its next report in 2007, basing its findings on a consensus-oriented process that involves hundreds of scientists as well as senior diplomatic officials.
The Atlantic had an unusual number of severe hurricanes last year, four of which hit Florida. In 2004, major tropical storms, including nine hurricanes, occurred in the Atlantic. Between 1974 and 1994, the Atlantic averaged 8.6 serious tropical storms annually.
Trenberth, who in an interview Friday called Landsea's charges "ridiculous," said he participated last fall in a media conference call organized by Harvard University professors "to correct misleading impressions that global warming had played no role at all in last year's hurricane season." He added he would have welcomed opposing views in the assessment, even though he believes "if global warming is happening, how can hurricanes not be affected? It's part of the overall system."
Landsea, who could not be reached for comment Friday, wrote in his resignation letter that a recent report from the Geophysical Fluid Dynamics Laboratory suggests that by 2080 hurricanes are likely to be only 5 percent more intense than they are now.
"I personally cannot in good faith contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound," he wrote.
IPCC officials have not intervened in the dispute. R.K. Pachauri, who heads the overall climate assessment, wrote in a Dec. 8 e-mail to Landsea that "individual scientists can do what they wish in their own right, as long as they are not saying anything on behalf of the IPCC."