Climategate, the 2009 exposure of misconduct at the University of East Anglia, was a terrible blow to the reputation of climatology, and indeed to that of British and American science. Although that story hasn’t been in the news in recent months, new evidence of similar scientific wrongdoing continues to emerge, with a new scandal hitting the climate blogosphere just a few days ago.
And central to the newest story is one of the Climategate scientists: Keith Briffa, an expert in reconstructing historical temperature records from tree rings. More particularly, the recent scandal involves a tree-ring record Briffa prepared for a remote area of northern Russia called Yamal.
For many years, scientists have used tree-ring data to try to measure temperatures from the distant past, but the idea is problematic in and of itself. Why? Because tree-ring data reflect many variables besides temperature. Russian tree growth, like that of trees around the world, also reflects changes in humidity, precipitation, soil nutrients, competition for resources from other trees and plants, animal behavior, erosion, cloudiness, and on and on. But let’s pretend, if only for the sake of argument, that we can reliably determine the mean temperature 1,000 years ago or more using tree cores from a remote part of Russia. The central issue that emerges is: How do you choose the trees?
It was the way Briffa picked the trees to include in his analysis that piqued the interest of Steve McIntyre, a maverick amateur climatologist from Canada. The Climategate e-mails make it clear that McIntyre earned the public scorn of the most powerful U.N. climatologists, including James Hansen, Michael Mann, and Phil Jones, while simultaneously earning their fear and respect in private.
McIntyre noticed a few problems with the way Briffa chose the sampling of Russian trees, and he wrote to Briffa requesting the data Briffa used in a published tree-ring paper. Briffa declined. And so began a four-year saga involving multiple peer-reviewed journals, behind-the-scenes maneuvering by Briffa and his closest confidants, and a Freedom of Information Act request on the part of McIntyre that appears to be on the verge of being granted. Even without the final set of data, however, McIntyre has shown beyond the shadow of doubt that Briffa may have committed one of the worst sins, if not the worst, in climatology — that of cherry-picking data — when he assembled his data sample, which his clique of like-minded and very powerful peers have also used in paper after paper.