HOUSTON, Texas - November 16, 2008 - Goddard Institute for Space Studies computerized temperature maps seemed to show readings across a large part of Russia had been up to 10 degrees higher than normal. But when expert readers of the two leading global warming-sceptic blogs, Watts Up With That and Climate Audit, began a detailed analysis of the GISS data, they made an astonishing discovery. 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.

The error was so glaring that when it was reported on the two blogs - run by the U.S. meteorologist Anthony Watts and Steve McIntyre, the Canadian computer analyst who won fame for his expert debunking of the notorious “hockey stick” graph - 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.