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Sunday, July 23, 2006
Is It All Just Hot Air?
By John Fleck
Journal Staff Writer
SANTA FE Greenland has become global warming's poster child: rising temperatures melt glaciers, threatening a devastating rise in sea levels that could inundate coastal cities around the world.
Greenhouse gases from factories and cars are to blame, according to the conventional story, which features prominently in Al Gore's documentary, "An Inconvenient Truth."
And yet there was Los Alamos National Laboratory climate scientist Petr Chylek last week, standing before a gathering of his colleagues to explain that Greenland isn't actually warming.
Chylek is a dissenter from the scientific mainstream. While most scientists think greenhouse gases are responsible for changes already seen in Earth's climate, Chylek believes the "data are inconclusive."
"You really cannot say for certain what is causing current climate change," Chylek said in an interview.
The Greenland story gained traction in February, when a team of U.S. scientists drew headlines around the world with new data suggesting Greenland's glaciers are melting and slipping into the ocean far more rapidly than previously thought.
Chylek shot back last month with evidence from Greenland temperature records showing the North Atlantic island was cooler in the second half of the 20th century than it was in the first.
The exchange is the sort of thing that happens all the time in science: researchers doing their best to make sense of imperfect and sometimes conflicting data.
But this is not just any science. In climate science, the debate over whether we need to change global energy production to reduce greenhouse gas emissions turns ordinary scientific disagreements into political minefields.
By all measures, there is widespread agreement among climate scientists on key points:
The Earth is warming.
Human exhaust primarily carbon dioxide, a "greenhouse gas" that holds heat close to the Earth's surface is likely a big part of the reason.
The more exhaust we spew, the more temperatures will go up.
But when you get into the details, as Chylek is quick to tell you, you find that climate science is not a monolith:
Could changes in the sun be responsible for some of the warming?
While scientists obsess over greenhouse gases, are they missing other things that could be having equally large effects on the climate?
Are the thermometer records that show warming as good as scientists think they are?
Contrary to the common perception of textbooks filled with fixed knowledge, real science is a tangled process fraught with uncertainties, and such debates are common in any field.
"Science," said Texas A&M climate scientist Andrew Dessler, "is this turbulent interface between what we know and what we don't know."
But if all science is turbulent, then climate science, because of its political dimensions, is all the more so.
Chylek placed that turbulence center stage last week, inviting more than a hundred scientists from around the world to Santa Fe for the 2nd International Conference on Global Warming, to discuss what scientists know and don't know about our changing climate.
He understands his views place him in a minority among his scientific colleagues.
Chylek opened the interview with the Journal by pointing out, carefully and firmly, that he speaks for himself on these questions, not for Los Alamos.
"We have many people in the lab who completely disagree with me," he said.
The conference, he said, was an attempt to recognize that a range of legitimate scientific views exists on global warming, and to encourage a discussion. To do that, Chylek invited both supporters of the mainstream view, as well as the most well-known skeptics.
Participants agreed Chylek achieved his goal.
"This is about one of the most diverse conferences there is," said University of Alabama climate scientist John Christy, perhaps the most prominent of the global warming renegades.
The range of views held by working climate scientists does not show up in the political version of the debate, according to Roger Pielke Jr., a University of Colorado political scientist who studies the politics of climate science.
The science becomes caricatured, according to Pielke, dichotomized into "skeptics versus alarmists ... even though it does not do justice to the complexities of the science debate."
Pielke has the pedigree to hold forth on the issue. His father, Roger Pielke Sr., is one of those hard-to-pigeonhole climate renegades.
A tiff the elder Pielke had last summer with The New York Times illustrates the problem. In a story, the Times characterized Pielke Sr. as "a scientist who has long disagreed with the dominant view that global warming stems mainly from human activity."
Pielke Sr.'s views are not nearly so black and white, and he demanded a correction. The result: It took the Times 74 words to correct the initial 18-word description.
"Humans are having a significant effect on the climate system," Pielke Sr. said in an interview during a break in Chylek's conference. It's a view that would seem to place him firmly in the mainstream. But it is not that simple.
Pielke Sr. thinks greenhouse gases are not the whole story. Massive human land-use changes wholesale shifts from forest to agriculture, for example are also important but are being given short shrift because of the emphasis on greenhouse gases.
Pielke Sr. also thinks global temperature data, the backbone of global warming claims, are fraught with uncertainties. And he is skeptical of the computer climate simulations used to forecast future climate change.
All of those legitimate scientific questions are lost in the simplified black-and-white version of climate science that shows up in public discourse, Pielke Sr. believes.
So what should the public, policymakers and politicians make of this debate, given the argument by some that there is enough scientific evidence to support action to reduce exhaust emissions?
The first thing is to recognize that the sort of renegades Chylek invited to his conference are honest scientists raising serious questions, said Chick Keller.
The second is to recognize the context surrounding the questions they are raising. While the questions are legitimate, they are not sufficient to undermine the vast evidence for greenhouse-caused global warming, said Keller, a retired Los Alamos National Laboratory climate modeler and a veteran of the climate science wars.
"The trouble with the Chyleks and the Pielkes and to some extent Christy is they're nitpickers," Keller said in an interview. "You can always find something wrong."
Pielke Sr., Chylek and Christy obviously don't think they're picking nits. So how should the public and policymakers, whipsawed by debate, sort out the competing claims?
"That's easy," said Dessler, co-author of Cambridge University Press's "The Science and Politics of Global Climate Change."
Dessler calls for the use of "expert assessments" panels of specialists brought together to sort out and summarize scientific information for politicians, policymakers and the public.
It's a common technique on all sorts of science-policy questions. On climate change, a number of such reviews have been done, including work by the Intergovernmental Panel on Climate Change and the National Academy of Sciences.
The panels' findings have been consistent and are reflected in the key finding in the IPCC's 2001 "Climate Change: The Science": Greenhouse gas emissions are altering Earth's climate.
Pielke Sr. has a different answer listen to more diverse scientific voices. He thinks expert panels like the IPCC are inbred, representing a narrow focus on greenhouse gases.
"The public is getting a very narrow view of the breadth of issues in climate science," he said.