January 26, 2010
EXCERPTS FROM- CLIMATEGATE ANALYSIS
by John P. Costella
March 2, 2001: email 0983566497
Chick Keller, of the Institute of Geophysics and Planetary Physics at the University of California at San Diego, United States, writes to Mike Mann, Ray Bradley, Phil Jones, Keith Briffa, Tom Crowley, Jonathan Overpeck, Tom Wigley, and Mike MacCracken, pointing out problems in the historical temperature estimates obtained from individual “proxy” methods:
Anyone looking at the records gets the impression that the temperature variation for many individual records or sites over the past 1000 years or so is often larger than 1°Celsius. … And they see this as evidence that the 0.8°Celsius or so temperature rise in the 20th century is not all that special.
He then makes note of a trick that they have used to mask this effect:
The community of climate scientists, however, in making averages of different proxies gets a much smaller amplitude of about 0.5°Celsius, which they say shows that reasonable combinations of effects can indeed explain this and that the 20th century warming is unique.
Keller realizes the mistake inherent in this trick shortly. First, he provides an excellent summary of the debate:
Thus, the impasse—one side the skeptics pointing to large temperature variations in many records around the globe, and the other side saying, “Yes, but not at the same time and so, if averaged out, is no big deal.”
He then points out that this glib brush-off is simply not valid:
But, just replying that events don’t happen at the same time (sometimes by a few decades) is the reason might not be enough. It seems to me that we must go one step further. We must address the question: what effects can generate large … temperature variations over hundreds of years, regional though they may be (and, could these occur at different times in different regions due to shifting climate patterns)? If we can’t do this, then there might be something wrong with our rationale that the average does not vary much even though many regions see large variations. This may be the nub of the disagreement, and until we answer it, many careful scientists will decide the issue is still unsettled, and that indeed climate in the past may well have varied as much or more than in the last hundred years.
This remarkable statement—mailed to all of the key players in this scandal—shows that they knew, clearly, more than eight years before the Climategate whistle-blower released these emails, that the entire basis of their claims was on shaky ground.
In his last paragraph, Keller points out the elementary mathematical error in the “averaging trick”:
Also, I note that most proxy temperature records claim timing errors of … 50 years ahead or behind the correct date or so. What is the possibility that records are cancelling each other out on variations in the hundred-year timeframe due simply to timing errors?
There are, in fact, many more mathematical reasons why the “averaging trick” is completely wrong; but Keller’s observation is completely correct, and by itself discredits the entire discipline of work establishing these “multi-proxy” historical temperature estimates