I can’t open the link to verify, but I believe Von Storch’s presentation indicated the reconstruction problems had no bearing on detection.

One might call that hand waving and expect it to get passed on into the report. Slightly more elaborate hand waving in the report would be preferable.

Perhaps they just ignore the elephant at the cocktail party instead?! .

Reconstructions of climate data for the past 1,000 years (Figure 1b) also indicate that this warming was unusual and is unlikely7 to be entirely natural in origin.

I think you are correct; the reconstructions are supportive, especially MBH, which suggests very little variability until the increased CO2 came along. There is some difficult in knowing how well the GCMs model climate, because you cannot perturb the system and test your GCMs. The period that we know is very short.

But formally, there is a distinction between how good the GCMs are, and how reliable the historical reconstructions are. You don’t need a historical reconstruction to have a GCM which is 99.99% accurate. I will say that it is a bit of a broad topic to opine on; I can’t really see how you could do anything more than arm-wave on this, especially with this panel’s already broad remit.

cheers
per

In case anyone doesn’t know, the NAS says:

“The National Academies perform an unparalleled public service by bringing together committees of experts in all areas of scientific and technological endeavor. These experts serve pro bono to address critical national issues and give advice to the federal government and the public. ”

What WordPress desperately needs is irony tags.

I’m sure that NAS would be more than happy to wade into the bigger quetions, but they’ll probably wait until after IPCC 4th Assessment Report and it will be a different panel. I have no problem with that.

The basic thrust of my post was that it appears that the report is going to try to be as uncontroversial as possible.

If my comment was ignorant, I apologize for any confusion.

CO2 is believed to be a major aspect of climate change, and in the mind of many, the reconstructions bolstered that theory. If the NAS panel feels the theory is unaffected or weakened, it’s hard to see how that is reported without some basic explanation of the theory.

I should add that, the theory apparently is not just that CO2 traps heat, but that when the various forcings without CO2 are added, that a negative sum results. I believe that this sort of information is generally buried in the fine print rather than being emphasized.

I thought the point of the NAS was to clear up things for the policy makers, not continue to bury things in fine print. If I have the science wrong, it is because the information is not being properly presented. Or I suppose I just have a screw loose.

In case anyone doesn’t know, the NAS says:

“The National Academies perform an unparalleled public service by bringing together committees of experts in all areas of scientific and technological endeavor. These experts serve pro bono to address critical national issues and give advice to the federal government and the public. “

Surely they can’t just say that it’s not central, and not explain why they continue to believe that CO2 is the chief culprit in climate change.

I am confused by this comment. The NAS panel doesn’t have to justify the IPCC’s stance, or anyone else’s. It just has to say what the scientific weight of evidence on a point is, and it can come to a different view from another NAS panel !

In short, they have no obligation to justify that CO2 is the chief culprit…
yours
per

“explain how central the debate over the paleoclimate temperature record is to the state of scientific knowledge on global climate change”

It will be interesting to see how much they are willing to say about that. Surely they can’t just say that it’s not central, and not explain why they continue to believe that CO2 is the chief culprit in climate change.

At the very least they ought to say what it’s based on, what the strengths and weaknesses are in those lines of evidence (or at least a picture of the uncertainties).

Perhaps they will have to modify their terms of reference again!

Nah! Notice carefully, the word “CO2″ appears nowhere in the terms of reference.

Another thing that does not appear are the names of three scientists referred to repeatedly by the Boehlert questions. When top scientists complained about the Barton questions they implied that the scientific establishment could keep its own house in order, yet they seem unwilling to name names.

Will be interesting to see if the report shrinks from naming the names of people or gasses.

Discuss how proxy data can be used to reconstruct surface temperature over different geographical regions and time periods. [new]

This seems to assume that proxy data can be used to reconstruct surface temperature.

This, to my mind, is yet to be proven, therefore it seems an odd assumption to make.