It’s a red letter day for us global warming deniers.
Over at Climate Audit Willis Escenbach has done some analysis on the temperature proxies used in Mann et al. (2008), the paper thay updated MBH98, in which Michael Mann introduced the "hockey stick" to the world.
That first paper in 1998 shocked the world by showing that the earth’s climate was pretty steady for the last 1,000 years, only shooting up when the industrial revolution got really started in the mid-19th century.
This was important because previously everyone had thought that the earth had been warmer than today in a Medieval Warming Period.
But Eschenbach’s analysis shows that the “hockey stick” signal is only carried by two sets of data series, or about 25 proxies out of the total of 95.
One set of data are three Tiljander lake sediment series from Finland. Tiljander has advised that these data should not be used as temperature proxies because they are corrupted by urban development in the last century and a half.
The other set of data are mostly the various bristle-cone pine series assembled by Donald Graybill. These are all from high-altitude pine trees in the US southwest. Writes Eschenbach:
[Graybill’s] work has been called into serious question by Linah Abadneh’s thesis, wherein she was unable to replicate his results.
What happens if you throw out the Tiljander lake sediments and the Graybill pines?
You get a chart that shows a Medieval Warming Period, a Little Ice Age, and temperatures today that are lower than they were a thousand years ago. What a surprise.