Wednesday, 19 November 2008

An embarrassing climate measurement mistake

Governments around the world are making expensive decisions designed to combat global warming based on the evidence provided by scientists showing that world temperatures are in fact rising. Most influential among those scientists is Dr James Hansen of Nasa's Goddard Institute for Space Studies (GISS) who has tackled the complex task of taking the readings from thousands of individual meteorological measuring stations to come up a virtual temperature reading for the world as a whole. So when GISS pronounced earlier this month that October 2008 was the warmest October on record there was a heightened sense of alarm among those with the task of reaching an international agreement to stop the dreaded gas emissions held to be responsible.

How embarrassing, then, that GISS has now had to withdraw its alarmist findings. Last month was only shown to be the hottest ever because the data Dr Hansen put in to his wonderfully powerful computer was substantially wrong.

You can get the picture from this pair of pictures which show a before the correction and after the correction computerised map of the world temperature in October. In the first map you will notice a large area of dark brown over Russia indicating average temperatures that were eight degrees and more above the average in the base period from 1951 to 1980. In the second map the brown has retreated considerably after a couple of sceptical climate change blogs, Watts Up With That and Climate Audit, began detailed analysis of the GISS data and made an astonishing discovery. As Christopher Booker reported in the London Daily Telegraph: "The reason for the freak figures was that scores of temperature records from Russia and elsewhere were not based on October readings at all. Figures from the previous month had simply been carried over and repeated two months running."

With itsw credibility under attack, GISS was forced into damage control. To quote Christopher Booker again:

"GISS began hastily revising its figures. This only made the confusion worse because, to compensate for the lowered temperatures in Russia, GISS claimed to have discovered a new 'hotspot' in the Arctic - in a month when satellite images were showing Arctic sea-ice recovering so fast from its summer melt that three weeks ago it was 30 per cent more extensive than at the same time last year.
A GISS spokesman lamely explained that the reason for the error in the Russian figures was that they were obtained from another body, and that GISS did not have resources to exercise proper quality control over the data it was supplied with. This is an astonishing admission: the figures published by Dr Hansen's institute are not only one of the four data sets that the UN's Intergovernmental Panel on Climate Change (IPCC) relies on to promote its case for global warming, but they are the most widely quoted, since they consistently show higher temperatures than the others."

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