North America’s premier weather agencies have been questioned over “homogenisation” changes to international temperature records used to declare last year the hottest on record.
Neither NASA nor the National Oceanic and Atmospheric Association have responded to international reports questioning why temperature records at three rural stations in Paraguay had been changed dramatically.
Independent climate researcher and blogger Paul Homewood said he had compared NASA data with the raw temperature data for the stations and found a cooling over a 65-year period had been turned into a warming trend.
The story was picked up internationally, including a long article in Britain’s Sunday Telegraph, and builds on a long-running controversy over the treatment of historic temperature records.
In Australia, the Bureau of Meteorology has been challenged over its homogenisation methods that have changed cooling trends to warming trends at some stations. BoM has maintained there are legitimate reasons to alter physical temperature records, including changes in recording equipment, and inconsistencies with temperatures at nearby areas.
An independent panel has been established to review BoM’s treatment of historical temperature data, as recommended by a peer review of the bureau’s national temperature data ACORN-SAT.
Mr Homewood was encouraged to examine NASA’s Goddard Institute for Space Studies records after the agency declared 2014 the hottest on record. NASA later admitted that given the small difference between recent temperature highs and the margin of error in recording, it was only 38 per cent certain 2014 was the warmest.
After checking raw data, Mr Homewood said past temperatures had been adjusted down by almost 2C and a declining temperature trend over 65 years in the raw data had been transformed into a sharply warming trend.