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Blogger Sceptics Change Climate History

Via Numberwatch Hush, not a word to the public!

Coyote Blog: Breaking News: Recent US Temperature Numbers Revised Downwards Today

This is really big news, and a fabulous example of why two-way scientific discourse is still valuable, in the same week that both Newsweek and Al Gore tried to make the case that climate skeptics were counter-productive and evil. 

Climate scientist Michael Mann (famous for the hockey stick chart) once made the statement that  the 1990's were the warmest decade in a millennia and that "there is a 95 to 99% certainty that 1998 was the hottest year in the last one thousand years."

Well, it turns out, according to the NASA GISS database, that 1998 was not even the hottest year of the last century. This is because many temperatures from recent decades that appeared to show substantial warming have been revised downwards. Here is how that happened....

Anthony Watts at SurfaceStations.org has lead an effort to photo-document these temperature stations as an aid to scientists in evaluating the measurement quality of each station.  The effort has been eye-opening, as it has uncovered many very poor instrument sitings that would bias temperature measurements upwards, as I found in Tucson and Watts has documented numerous times on his blog.

One photo on Watt's blog got people talking - a station in MN with a huge jump in temperature about the same time some air conditioning units were installed nearby.   Others disagreed, and argued that such a jump could not be from the air conditioners, since a lot of the jump happened with winter temperatures when the AC was dormant.  Steve McIntyre, the Canadian statistician who helped to expose massive holes in Michael Mann's hockey stick methodology, looked into it.  After some poking around, he began to suspect that the GISS data base had a year 2000 bug in one of their data adjustments.

Unfortunately, it was hard to prove.  Why?  Well, that highlights one of the great travesties of climate science.  Government scientists using taxpayer money to develop the GISS temperature data base at taxpayer expense refuse to publicly release their temperature adjustment algorithms or software (In much the same way Michael Mann refused to release the details for scrutiny of his methodology behind the hockey stick).  Using the data, though, McIntyre made a compelling case that the GISS data base had systematic discontinuities that bore all the hallmarks of a software bug.

Today, the GISS admitted that McIntyre was correct, and has started to republish its data with the bug fixed.  And the numbers are changing a lot.  Before today, GISS would have said 1998 was the hottest year on record (Mann, remember, said with up to 99% certainty it was the hottest year in 1000 years) and that 2006 was the second hottest.  Well, no more.  Here are the new rankings for the 10 hottest years in the US, starting with #1:

1934, 1998, 1921, 2006, 1931, 1999, 1953, 1990, 1938, 1939

Three of the top 10 are in the last decade.  Four of the top ten are in the 1930's, before either the IPCC or the GISS really think man had any discernible impact on temperatures. 


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