This is Dr. James Annan's blog. He is one of the core scientists of the climate consensus being the co-author of the "Annan and Wahl, et al." paper on tree ring climate reconstructions that the Mike Mann MBH 1998 paper is based on.
Science moves forward and Annan is now asserting that we cannot claim the large amplification forcing factors associated with previous works in CO2 forcing as the models and the predictions simply do not fit the observational data.
This is from the IPCC's unreleased AR5 draft chapter 12
It seems very odd to portray our work as an outlier here. Sokolov et al 2009, Urban and Keller 2010, Olson et al (in press JGR) have also recently presented similar results (and there may be more as yet unpublished, eg Aldrin at the INI meeting back in 2010). Such "observationally constrained pdfs" were all the rage a few years ago and featured heavily in the last IPCC report, there is no clear explanation for your sudden dismissal of them in favour of what seems to be a small private opinion poll. A more balanced presentation could be: "Annan and Hargreaves (2011a) criticize the use of uniform priors and argue that sensitivities above 4.5°C are extremely unlikely (less than 5%). Similar results have been obtained by a number of other researchers [add citations from the above]."
Even the 4.5 degree number is increasingly seen as untenable.
But the point stands, that the IPCC's sensitivity estimate cannot readily be reconciled with forcing estimates and observational data. All the recent literature that approaches the question from this angle comes up with similar answers, including the papers I mentioned above. By failing to meet this problem head-on, the IPCC authors now find themselves in a bit of a pickle. I expect them to brazen it out, on the grounds that they are the experts and are quite capable of squaring the circle before breakfast if need be. But in doing so, they risk being seen as not so much summarising scientific progress, but obstructing it.
The consensus is crumbling folks, no matter how much the activists blind mantra of consensus continue to scream that it is intact.