Gavin's post is about a press release regarding the latest paper on the Methane 'Belch' which caused the minor extinction that marked the change from Paleocene to Eocene epochs 55 million years ago. Global temperatures during the Paleocene were similar to the the hot house world of the Cretaceous when the dinosaurs roamed the world, but the methane belch raised the temperatures even higher. We know the cause was methane because of the change in the fraction of carbon 13 that is recorded in fossils from that time. The problem is that the greenhouse effect of the estimated amount of methane, or of the carbon dioxide if the methane burned, does not account for the large rise in temperature. Obviously the models are wrong, and that is what the press release said and the title of the paper implied: Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming.
Gavin, as a climate modeller, plays down that issue despite the quotation in the press release from one of the authors which reads:
"In a nutshell, theoretical models cannot explain what we observe in the geological record," said oceanographer Gerald Dickens, a co-author of the study and professor of Earth science at Rice University. "There appears to be something fundamentally wrong with the way temperature and carbon are linked in climate models."
Instead, he mentions the point that this implies warming will be worse rather than less as the deniers are claiming. Then he rambles off contradicting what he has just said. He argues that the back of an envelope calculations done twenty years ago are still accurate, citing Annan and Hargreave's paper as proof. But that paper, like the estimate it justifies is merely calculates an average. It is meaningless for describing the behaviour of a non-linear system.
Gavin admits that the polar regions will warm more than the tropics, so the climate sensitivity in one region is different from that in another. The Zeebe et al paper is saying that the climate sensitivity during the Paleo-Eocene transitiorn was different from now. And the abrupt changes before and after the Younger Dryas don't fit with today'st climate sensitivity either. So not only does climate sensitivity vary geographically, it varies temporally too.
Changing it name from Charney Sensitivity to Earth System Sensitivity does not solve the problem. Sensitivity is just as chaotic as the surface temperature. Or if there is a carbon dioxide sensitivity, a fixed relationship between carbon dioxide concentration and its forcing, then it is clear we have not found it yet. That means the models are not correct - they are wrong!
As I see it, the danger is that by insisting that it is only weather that is chaotic, and that climate is linear, the potential for abrupt climate change is being ignored. The scientific establishment, excluding Hansen, Lovelock and Broecker, are too conservative to accept that catastrophe is around the corner. RealClimate is not fighting skepticism, it is breeding complacency.

