ohn Goetz, writing last month in the science blog Climate Audit, analyzed the way NASA's Goddard Institute for Space Studies calculates estimated global surface temperatures and showed that the addition of new, contemporary data could "have a ripple effect all the way back to the beginning of a [weather] station's history."So what does this mean? It means that by manipulating the data to serve Algore, NASA has made itself the outlier among the three primary climate data sources.
Goetz found 32 different versions of published global annual averages going back to Sept. 24, 2005, that showed the published figures – figures used as a baseline to demonstrate change through time – changing hundreds of times.
"On average 20% of the historical record was modified 16 times in the last 2 1/2 years," he wrote. "The largest single jump was 0.27 °C. This occurred between the Oct. 13, 2006 and Jan. 15, 2007 records when Aug 2006 changed from an anomoly of +0.43 °C to +0.70 °C, a change of nearly 68 percent."
Temperature anomalies – differences between the average measured global air temperature and some long-term mean – are primary data for studies of climate change.
The magnitude of the changes in the reworked historical data observed by Goetz – 0.27 °C – is more that a third of the total average increase in global air temperature near the Earth's surface – 0.74 ± 0.18 °C – that has occurred over the last century, according to the Intergovernmental Panel on Climate Change.
The University of Alabama at Huntsville and Remote Sensing Systems provide data gathered by Earth-observation satellites. Satellite temperature data has the advantage of being gathered across the entire surface of the Earth, except for regions near the two poles, but it is unavailable for the period prior to 1978.Is there a political motive involved in NASA's data "massaging?" I'll take James Hansen's word for it on this one.
How do these other data sources compare to NASA?
According to Hadley's data, worldwide temperatures have declined since 1998 and the Earth is not much warmer now than it was than it was in 1878 or 1941.
Both the UAH and RSS satellite data agree with Hadley and show temperatures declining over the past decade with only a slight increase above the 30-year average between 1978 and 2008.
More recently, NASA temperatures indicated March 2008 was the third-warmest March in history. RSS and UAH showed the same month as only slightly above average globally and the second-coldest ever in the southern hemisphere.
James Hansen, head of NASA's Goddard Institute for Space Studies, warned in 2006 "we have a very brief window of opportunity to deal with climate change ... no longer than a decade, at the most" – the same week the National Oceanic and Atmospheric Administration issued a report saying the U.S.'s hottest year was in the past, 1936.