Why climatologists used the tree-ring data ‘trick’

If anything, I would expect the relatively recent divergence of correlation between tree-ring measurements and other climate measurements to bolster claims of an unstable climate, rather than suggest cooling.

Here we have a situation where plant behavior closely follows other measurements of the climate for a very long time, and then recently ... they don't. The most likely explanation here -- still being studied, mind you -- is that there has been a significant change in the interaction between trees and environment in certain areas.

Not to disagree with you that ad hominem attacks aren't helpful, but the article laid out a lot of interesting data based arguments which you yourself completely ignored. Intentionally or not, you instead preceded to cast "the science" into doubt in an ad hominem fashion. Ad hominem attacks are besides the point, and degrade conversion, but just because people use them doesn't make everything they say wrong.

Sure (though the millions at stake in academic research particularly given the political climate as the leaked emails illustrate are also of significance) - but let's first separate the conversation to understanding that (1) what's the problem and (2) what we should do about it are two separate issues.

Let's also understand that much of the western world like the US are about to show significant declines in carbon emissions irrespective of what Fox news or any other polemics - pro or con say. (ref: http://www.guardian.co.uk/environment/2009/oct/15/us-decline...)

Thanks (sincerely) for being honest about that, at least.

There were two clues: one, your comment timestamp was not far removed from the time that the article was posted. I read pretty quickly, but it still took me some time to fully read and digest the entire article.

Second, there was your statement: "their tree-ring data is not a useful proxy for temperature". The article specifically mentioned that tree-ring data correlated with other proxies for temperature measurements, as well as going into other details (like the difference between measuring ring thickness and ring density, and the fact that there has only somewhat recently been a divergence between the measurements). Basically, the article answered your statement, I think.

I have spent some hundreds of hours listening to arguments for global warming, er Catastrophic Anthropogenic Climate Change or AGW or ACC (or whatever the PC acronym is this week)

The problem that I keep getting back to is best phrased like this: archaeological climate record extrapolation is nowhere near as sure-fire as supporters make it out to be. I have many more problems, but this one addresses the current article.

I understand these are honest, hard-working scientists, and they know a heckuva lot more than I do about their particular area, but as an intelligent person I can make fairly informed guesses based on the standards of proof required and the types of phrases being used. There a lot of "it appears" and "it seems" in there, phrases that mean that while consensus has been achieved (we'll take that as a given for this comment) it's nowhere near a slam-dunk. There's also quite a bit of ad-hominem character assassination going on, even in this piece. I find that folks who have to result to labeling and name-calling usually are insecure about their position.

Especially troubling is the way the current divergence is addressed. The argument looks to me like "we can use this data as a proxy for all periods except those where we have direct measurements to verify correlation" I find that weak at best.

To me, the layman, tree-ring data is going to show you how well a certain tree grew in a certain place over time. That might or might not have implications for the larger area or the entire planet. Like so many other pieces of this argument, it depends on having a control group and repeatable experiments -- none of which are doable. So it boils down to speculation. Speculation by great, intelligent people, perhaps, but speculation nonetheless.

I know some folks will say "no matter what the proof you're never going to believe" I don't know how to respond to that, except to point out that I've always been more interested in the character of the debate around GW and the political implications of letting scientific consensus drive public policy more than I have the actual facts on the ground. I have no more emotion invested in whether the planet is cooling or warming than I do variations of the gravitational constant around the time of the big bang. Whichever way the facts lead will not change my underlying concern. So I really don't have a dog in this fight as far as the science goes, at least not to the degree that some others do.