Yes, if I recall, the problem was the tree-ring data didn’t match recent climate trends. The main mistake, I think, was that when they made a chart of the warming, they didn’t explain that the first part of it was from tree-ring data, and the last part from temp measurements (and they use some “tricks” to splice the two data sets together).
But tree rings aren’t the only climate proxy. See this post by a young paleoclimatologist commenting on a
RC post:
Something this article (and many others) ignores is that there are far more paleoclimate proxies than tree rings. Chironomids, foraminifera, cosmogenic isotopes, conodonts (if you wanna get “really” paleo), varves, oxygen isotope ratios in clam shells and other organic matter, and of course, more well known ice cores. I’m a budding paleoclimatologist, not a statistician, so I can’t speak to any of the methods used, but there seems to be an attitude in many circles and in this article that tries to pretend that tree rings are all we have, which couldn’t be further from the truth. The best use of proxies is when combining several methods. Take a look at this paper on Baffin Island
glyfac.buffalo.edu/Faculty/briner/buf/pubs/Thomas_et_al_2010.pdf On the 14th page, you can see the a graph depicting the use of several proxies and how they all agree quite nicely, especially considering the temporal scale in question. The McShane and Wyner article claim it’s very difficult to reconstruct past climates, but apparently, they haven’t been paying attention. There are people out there who have gotten pretty good at it.
Comment by Shirley J. Pulawski — 25 August 2010 @ 3:46 PM
I’m also thinking about why trees don’t make good proxies in recent years. I’ve been studying about how AGW & its effects (& increased CO2) affect plants. There could be some good reasons for trees being affected differently in our time.