Playing fair on warming debate

Local modeling questionable

Published August 6, 2006 at midnight

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Amonth ago, it was California's wine country that was supposedly imperiled. More recently, it was environmental treasures throughout the West, including Rocky Mountain and Mesa Verde national parks. Stories predicting that global warming will lay waste to America's outdoor wonders are popping up with greater regularity.

But is climate science so sophisticated that it can predict the localized effects of any future global warming?

The majority of scientists working with the United Nations' Intergovernmental Panel on Climate Change think not. The San Francisco Chronicle reported last month that most of them find local climate projections unreliable.

Meantime, former Colorado state climatologist Roger Pielke Sr., who's now at the University of Colorado, dismisses outright the prospect of using localized modeling to forecast crop production or weather patterns decades hence.

Several undeniable trends in the West are indeed troubling - the lingering drought and shrinking glaciers among them. It's perfectly legitimate to debate what, if anything, can be done to moderate such trends. (Our belief: not nearly as much as some activists claim.) But such debates ought to be conducted without the sort of alarmist rhetoric that some of these dubious localized reports have provoked.

The wine country study suggests that the U.S. could lose 81 percent of its wine-producing acreage to global warming by 2100. It was funded in part by the National Center for Atmospheric Research in Boulder - obviously a serious outfit. Still, the methods used - which project local weather trends decades from now based on global climate models - have been discounted by other climatologists, including Pielke, Kenneth Trenberth at NCAR, and John Christy at the University of Alabama. They argue that global models are not robust enough to accurately forecast local climate patterns and farm output.

Using that localized methodology, the study's lead author, Noah Diffenbaugh at Purdue University, published a paper last year suggesting that by the end of this century, "winter as we know it will likely disappear in the Northeast." Pielke dismissed the paper on his Climate Science blog (climatesci.atmos.colostate.edu/), stating that Diffenbaugh's method of prediction is not accurate enough to "add appropriate insight to be used by policymakers."

Christy, who's also Alabama's state climatologist, also distrusts localized forecasts. He told the Chronicle, "I would not base economic decisions on the output of regional predictions from these models."

The report on national parks is a review of research and reports compiled by the Rocky Mountain Climate Organization, a consortium of Colorado government agencies and environmental groups. This study also tries to localize a complicated regional issue.

Global warming long ago entered the realm of politics, where the debating standards make little attempt to exclude distortion and even outright invention. But citizens struggling to honestly assess the issue need to know that local climate modeling is not yet a solid guide to policy.

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