Wednesday, February 01, 2012

Email 4413, Oct 2009: Environmental plant physiologist writes to Briffa: "As time has progressed I have found myself more concerned with the whole scientific basis of dendroclimatolog"

Email 4413

As an environmental plant physiologist, I have followed the long debate
starting with Mann et al (1998) and through to Kaufman et al (2009).
As time has progressed I have found myself more concerned with the whole
scientific basis of dendroclimatology. In particular;
1) The appropriateness of the statistical analyses employed
2) The reliance on the same small datasets in these multiple studies
3) The concept of "teleconnection" by which certain trees respond to the
"Global Temperature Field", rather than local climate
4) The assumption that tree ring width and density are related to temperature
in a linear manner.

Whilst I would not describe myself as an expert statistician, I do use
inferential statistics routinely for both research and teaching and find
difficulty in understanding the statistical rationale in these papers.

As a plant physiologist I can say without hesitation that points 3 and 4 do
not agree with the accepted science.

1 comment:

TravelerDiogenes said...

Prior to CG2.0 I'd found that tree-rings are also used as a proxy for precipitation. This disturbed me greatly, as they can't be reliable for BOTH precip and temps.

When CG2.0 hit, in reading emails, then following their trails through all the papers I could access, it is obvious not only that the DP is real, but that tree-rings never DID function as proxies for temps. The 1880-1940 correlation seems to have been spurious, since the post-1940 period and the pre-1880 period did not show any such alignment.

Briffa and this Donald Keiller - as well as others - all seem to be alert to this, even as they certainly don't WANT it to be true. If it is, it blows dendroclimatology out of the water. The ONLY thing supporting it was that the connection sounded reasonable and for a while they seemed to correlate. Sure, warmer weather seems perfectly logical as a boost for tree-ring growth. But it also seems quite reasonable that heavier objects fall faster than lighter objects. So, until it proves itself out, it is just a hypothesis. But when there are 70 years of DP, what more proof does there have to be that, though it sounded reasonable, it just didn't pan out.

Of course, for paleoclimatology the death of dendroclimatology would be a disaster - and they all know it.

As of now, I am 100% certain that dendroclimatology has no basis.