It was already known that the Yamal series contained a preposterously small amount of data. This by itself raised many questions: Why did Briffa include only half the number of cores covering the balmy interval known as the Medieval Warm Period that another scientist, one with whom he was acquainted, had reported for Yamal? And why were there so few cores in Briffa’s 20th century? By 1988, there were only twelve cores used in a year, an amazingly small number from the period that should have provided the easiest data. By 1990, the count was only ten, and it dropped to just five in 1995. Without an explanation of how the strange sampling of the available data had been performed, the suspicion of cherry-picking became overwhelming, particularly since the sharp 20th-century uptick in the series was almost entirely due to a single tree.
The intrigue deepened when one of the Climategate e-mails revealed that, as far back as 2006, Briffa had prepared a much more broadly based, and therefore more reliable, tree-ring record of the Yamal area. But strangely, he had decided to set this aside in favor of the much narrower record he eventually used.
The question of Yamal had rightly come up when Briffa was questioned by Climategate investigators. He told them that he had never considered including a wider sample than the one he went with in the end, and hadn’t had enough time to include a wider one. However, the specific issue of the suppressed record appears to have largely been passed over by the panel, and Briffa’s explanation, like so many others given to the Climategate inquiries, appears to have been accepted without question.
But the ruse has now been shot to pieces, by the recent decision from the U.K.’s information commissioner that Briffa can no longer withhold the list of sites he used in his suppressed regional record for the Yamal area. The disclosure of these sites has allowed McIntyre to calculate what the broad series would have looked like if Briffa had chosen to publish it. He has shown that it has no hint of the hockey-stick shape that Briffa’s cherry-picked data indicated. Briffa’s decision to publish an alarming but unreliable version of the Yamal series — instead of a more reliable and thoroughly unremarkable one — has been the talk of the climate blogosphere, with many prominent commentators openly speaking of dishonesty.
Two and a half years after the initial revelation of the Climategate e-mails, new controversies, on the part of the scientists and the investigators involved, continue to emerge. Many of the players involved are desperate to sweep the scandal under the rug. However, their machinations have only succeeded in bringing renewed attention to their questionable science and ugly behind-the-scenes shenanigans, reigniting hope that more complete and more independent investigations — on both sides of the Atlantic — will yet be performed.
— Andrew Montford is the author of The Hockey Stick Illusion and the proprietor of the Bishop Hill blog. Harold Ambler is the author of Don’t Sell Your Coat and the operator of the blog talkingabouttheweather.com.