Fraudster Mann claims that tree-ring data stopped reflecting true temperatures 50 years ago; "maybe we can't trust" climate model predictions

Cosmic Log - Life after Climategate

Although Mann didn't exactly say "Bring it on," he did note that "those on the other side of the aisle will see this as an opportunity." He doesn't think scientists will be pushed on the defensive by their congressional critics.

"We should look at this as an opportunity for offense," he said.
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At the same time, he acknowledged that there have been uncertainties in the data, as well as missteps in the way those data have been presented.

For example, one study that became the focus of the Climategate e-mail debate used tree-ring measurements as a proxy for temperatures up to 1960, but switched to a different data set after that point. Mann said that the tree-ring data stopped reflecting true temperatures 50 years ago for reasons that are not yet fully known -- but he added that it was a mistake not to show the data anyway. "That was bad," he said. (A British inquiry into Climategate criticized the "misleading" portrayal of tree-ring data as one of the few scientific lapses in the scientists' conduct. One of the researchers said in an e-mail that he picked up the tree-ring "trick" from Mann.)

The uncertainties have more to do with exactly how hot things will get if current trends continue, rather than whether or not global temperatures will heat up. Mann said it's not known just how much of a positive feedback effect a warmer, moister atmosphere and the increased cloud cover might have -- which is why projections for the global temperature rise by 2100 vary by several degrees. Also, it remains to be seen how well scientists are modeling the effect of weather patterns such as El Nino and La Nina. If the models are off, "maybe we can't trust what they're predicting" when it comes to climate change on a region-by-region level.
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During his talk, Mann flashed a picture of his daughter and a polar bear at a zoo. "I can't imagine having to tell my daughter when she's grown up that polar bears became extinct ... because we didn't act soon enough to combat a problem that we knew was real, but we couldn't convince the public because we faced so much opposition from a very well-funded, very well-organized effort to distract the public," [What, specifically, does Mann know about the alleged funding and organization of climate realists?] Mann said.
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It might sound as if Mann relishes the fight, but he acknowledged that life after Climategate has not been easy for him. His routine now includes dealing with veiled death threats as well as investigations such as the one in Virginia. (The University of Virginia has reportedly run up a legal tab totaling $350,000 to fend off the state attorney general.) Mann is doing less research, and more speaking and writing. (For example, he's one of the scientists behind the RealClimate blog.)

"I spend quite a bit of time these days on what I might generously describe as outreach," he told me. "I think not every scientist should be doing this -- but more scientists should."