East Anglia Confirmed Emails from the Climate Research Unit - 1255477545.txt

From: Tom Wigley <wigley@xxxxxxxxx.xxx>
To: Rick Piltz <piltz@xxxxxxxxx.xxx>
Subject: Re: FYI--"Phil Jones and Ben Santer respond to CEI and Pat Michaels attack on temperature data record"
Date: Tue, 13 Oct 2009 19:45:45 -0600
Cc: Thomas.R.Karl@xxxxxxxxx.xxx, Jim Hansen <jhansen@xxxxxxxxx.xxx>, Steve Schneider <shs@xxxxxxxxx.xxx>, Gavin Schmidt <gschmidt@xxxxxxxxx.xxx>, Kevin Trenberth <trenbert@xxxxxxxxx.xxx>, Michael Mann <mann@xxxxxxxxx.xxx>, Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>, Phil Jones <P.Jones@xxxxxxxxx.xxx>, Ben Santer <santer1@xxxxxxxxx.xxx>

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Dear folks,

You may be interesting in this snippet of information about
Pat Michaels. Perhaps the University of Wisconsin ought to
open up a public comment period to decide whether Pat Michaels,
PhD needs re-assessing?

Michaels' PhD was, I believe, supervised by Reid Bryson. It dealt
with statistical (regression-based) modeling of crop-climate
relationships. In his thesis, Michaels claims that his statistical
model showed that weather/climate variations could explain 95%
of the inter-annual variability in crop yields. Had this been
correct, it would have been a remarkable results. Certainly, it
was at odds with all previous studies of crop-climate relationships,
which generally showed that weather/climate could only explain about
50% of inter-annual yield variability.

How did result come about? The answer is simple. In Michaels'
regressions he included a trend term. This was at the time a common
way to account for the effects of changing technology on yield. It
turns out that the trend term accounts for 90% of the variability,
so that, in Michaels' regressions, weather/climate explains just 5
of the remaining 10%. In other words, Michaels' claim that
weather/climate explains 95% of the variability is completely
bogus.

Apparently, none of Michaels' thesis examiners noticed this. We
are left with wondering whether this was deliberate misrepresentation
by Michaels, or whether it was simply ignorance.

As an historical note, I discovered this many years ago when working
with Dick Warrick and Tu Qipu on crop-climate modeling. We used a
spatial regression method, which we developed for the wheat belt of
southwestern Western Australia. We carried out similar analyses for
winter wheat in the USA, but never published the results.

Wigley, T.M.L. and Tu Qipu, 1983: Crop-climate modelling using spatial

patterns of yield and climate: Part 1, Background and an example from

Australia. Journal of Climate and Applied Meteorology 22, 1831

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