Prof. Mann's Proxy Temperature reconstruction challenged!

[sandlapper]

During the preparation of the IPCC's Third Assessment Report Prof. Michael Mann of the U. of Virginia completed an 800 year compilation of proxy temperature records, mainly from tree rings. This record indicated temperature remaining almost constant for nearly 700 years only to rise abruptly in the past century. It has been referred to, generally derogatorily, as the "hockey stick" because of this shape.

Now two Canadian authors writing in the periodical Energy & Environment challenge both the quality control of the data and the methodology of this reconstruction.See the synopsis here.

It looks reminescent of Bjorn Lomborg's attack on his "litany" in The Sceptical Environmentalist.

[pw]

1. One obvious flaw

in the "corrected" version is that they don't show the error bars on the older data. When you're comparing new information that is very accurate to older information that is not nearly so precise, you have to put the uncertainties on the graph for it to make a lot of sense. All of the "corrections" made in the early centuries appear to be well within the originally-claimed uncertainty, so without seeing the new error bars, you're not really seeing anything.

[sandlapper]

2. Seems like a useful comment.

McKittrick appears to be soliciting comments to his web site. Claims to have sought responses to a number of questions from Prof. Mann who demurred because of other demands on his time.