Skeptical Science examines the science of climate skepticism. From what I’ve seen of it they avoid the tendency of warmists to argue from authority.
The point of the Hockey Team’s research is to show that recent warming is unprecedented. Skeptics argue that tree ring proxies are unreliable and that the medieval warm period was warmer, or about as warm as, current temperatures. Skeptical Science argues that you can get a hockey stick without tree rings. It’s a good, honest looking article.
The first three graphs show temperatures determined from boreholes, stalagmites and glaciers respectively. But these series only go back as far as 1500, not to the medieval warm period. But:
When you combine all the various proxies, including ice cores, coral, lake sediments, glaciers, boreholes & stalagmites, it’s possible to reconstruct Northern Hemisphere temperatures without tree-ring proxies going back 1,300 years
The source? Mann 2008 (and a broken link at the time of writing, unfortunately).
The graph that accompanies this is interesting. It’s a little too small, but the steep red line is the CRU land based temperature record, which is subject to climategate. The steep grey line is another land based temperature record called HAD. I think this refers to the Hadley Centre which is the Met Office’s climate research centre. I’m not sure what the connection is but there are data sets referred to as HADCRU. In any case all land temperature measurements are suspicious because of urbanisation.
None of the other lines look particularly impressive regarding current warmth compared to medieval warmth. The dark blue line is “CPS land+ocn with uncertainties”, whatever that is. The pink line (Moberg et al) doesn’t look alarming at all.
There is another worry about all these proxies, described by Bod in response to Michael Jennings’ post about peer review:
My understanding is that the CRU’s (and GISS’ for that matter) numbers – I hesitate to call it data – are used for calibration purposes, thereby tainting any other research that uses it. This double-damns CRU’s whole research department, right the way back to HADCRU1 and beyond, and should render these people persona non grata across the entire scientific community if what’s been uncovered is true. This is the equivalent of cutting 25.4 mm off the end of the standard metre. (Yeah, I know they don’t use the metre now)