Larry placed this in the comment thread for last post on this particular topic (a few back) but I am "upgrading" it so that it doesn't get overlooked & so debate/discussion can continue if there's interest. In response to last line of Larry's report -- a bet on the river, essentially -- I check raise with an older post from Revkin!
Late, but still pertinent, here's Judith Curry's own scholarly rejoinder, including Mann/Nucitelli, the Economist, and a variety of other papers on both sides of the climate sensitivity issue -- her synthesis:
Mann and Nuccitelli state:
"When the collective information from all of these independent sources of information is combined, climate scientists indeed find evidence for a climate sensitivity that is very close to the canonical 3°C estimate. That estimate still remains the scientific consensus, and current generation climate models — which tend to cluster in their climate sensitivity values around this estimate — remain our best tools for projecting future climate change and its potential impacts."
The Economist article stated:
"If climate scientists were credit-rating agencies, climate sensitivity would be on negative watch. But it would not yet be downgraded."
The combination of the articles by Schlesinger, Lewis, and Masters (not mentioned in the Economist article) add substantial weight to the negative watch.
In support of estimates on the high end, we have the Fasullo and Trenberth paper, which in my mind is refuted by the combination of the Olson et al., Tung and Zhou, and Klocke et al. papers. If a climate model under represents the multidecadal modes of climate variability yet agrees well with observations during a period of warming, then it is to be inferred that the climate model sensitivity is too high.
That leaves Jim Hansen’s as yet unpublished paper among the recent research that provides support for sensitivity on the high end.
On the RealClimate thread, Gavin made the following statement:
"In the meantime, the ‘meta-uncertainty’ across the methods remains stubbornly high with support for both relatively low numbers around 2ºC and higher ones around 4ºC, so that is likely to remain the consensus range."
In weighing the new evidence, especially improvements in the methodology of sensitivity analysis, it is becoming increasing difficult not to downgrade the estimates of climate sensitivity.
And finally, it is a major coup for the freelance/citizen climate scientist movement to see Nic Lewis and Troy masters publish influential papers on this topic in leading journals.
Should indicate, if nothing else, that debate over this significant point continues, and that climate ideologues committed to heightening alarm in order to achieve political (and these days often financial) ends indeed have cause for concern.
Oh yeah? Well, consider what the sagacious science writer Andy Revkin says. I think he is seeing more clearly than the climate-policy activists who seem to view the debate featured in the Economist article as putting them in a bad spot. He concludes that if sensitivity is recalibrated to reflect over-estimation, the message is simply, "hey, there's more time to try to work this problem out ... phew!" So my sense of puzzlement continues.