Don Easterbrook is back, and his misunderstanding of Greenland’s climate history rides again in two remarkable posts at µWatts — attempted demolitions of the new paper every denier worth his (or her) salt is frothing at the mouth to claim has been rubbished, the 11,300 year global paleoclimate reconstruction of Marcott et al. Unfortunately Easterbrook is as far off the mark in his two essays at µWatts (one, two) as he has ever been, which makes not only him look stupid, but everyone who relies on his “work”.

The easiest thing for me to do to debunk Don would have been to republish this post from January 2011, because all of the points I make there remain true, and are sufficient to discredit Easterbrook’s interpretation of Greenland temperatures and their relevance to Marcott et al, but this time round Don has actually added a couple of extra mistakes — I presume just to keep people like me on their toes. So, for the record, here are Don’s new errors:

In a graph in his first “paper”, Easterbrook adds 0.7ºC to the last temperature point on the GISP2 Greenland temperature record to represent warming over the last 100 years. As I pointed out two years ago, you can’t use Greenland as a proxy for global temperature changes, because temperatures there are much more variable the global average — approximately twice as variable, as I quantified here. Warming in that part of Greenland has been more like 1.4ºC over the last century.

In his second “paper”, Easterbrook refers to the “top” of the GISP2 core as being 1950 . Unfortunately, he’s wrong (again). The temperature series is dated in years before present (BP), where present is defined as 1950. That makes the last temperature point on the GISP2 reconstruction 95 years before 1950 — in other words, 1855. All the fiddling with local temperature records that he does to try and demonstrate that current Greenland temperatures are not much different to 1950 are not only juvenile , but wrong headed because he still remains confused about the data he’s fiddling with.

. Unfortunately, he’s wrong (again). The temperature series is dated in years before present (BP), where present is defined as 1950. That makes the last temperature point on the GISP2 reconstruction 95 years before 1950 — in other words, 1855. All the fiddling with local temperature records that he does to try and demonstrate that current Greenland temperatures are not much different to 1950 are not only juvenile , but wrong headed because he still remains confused about the data he’s fiddling with. In one respect he remains entirely consistent: he still can’t spell Kurt Cuffey’s name.

And finally, just to explain why Don and Tony and James and Steve and everyone else have got their knickers in a twist, here’s the big picture: temperatures through the last ice age stitched on to Marcott et al’s Holocene reconstruction, with what we expect to happen over the next century pasted on to the end. If that looks like a brick wall we’re about to run into, then you’re probably right.

[Graph courtesy of Jos Hagelaars and Bart Verheggen]

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