Anthony Watts calls attention to a new study on the famed/infamous "hockey stick" graph purporting to show a huge uptick in global temperatures in the 20th century.

There is a new and important study on temperature proxy reconstructions (McShane and Wyner 2010) submitted into the Annals of Applied Statistics and is listed to be published in the next issue. According to Steve McIntyre, this is one of the “top statistical journals”. This paper is a direct and serious rebuttal to the proxy reconstructions of Mann.

Proxies are things like tree rings and ice core measurements, rather than actual thermometer readings.  From the paper’s abstract:

We find that the proxies do not predict temperature significantly better than random series generated independently of temperature. Furthermore, various model specifications that perform similarly at predicting temperature produce extremely different historical backcasts. Finally, the proxies seem unable to forecast the high levels of and sharp run-up in temperature in the 1990s either in-sample or from contiguous holdout blocks, thus casting doubt on their ability to predict such phenomena if in fact they occurred several hundred years ago.

The first sentence says essentially that proxy data does not predict future temperatures any better than picking temperature numbers at random. 

Wow.

I imagine this study will get a good looking-over by those on both sides of the issue, but if it stands scrutiny it would be a huge blow to the anthropogenic global warming theory.  Stay tuned.

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Filed under: Doug • Environment • Global Warming • Science

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