Methodology used by NASA to estimate rates of climate change are resulting in dramatic shifts in previously published historical temperature data, causing figures for estimated global surface temperature prior to 1970 to now be lower and figures since 1970 to now be higher – and appearing to provide evidence for those who say the Earth is warming.

John 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.”

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.

U.S. Temparature Anomalies -- 1999 report
U.S. temperature anomalies — 1999 report

A comparison of annual temperature anomalies for the United States from 1880 to 1999 further revealed that shifts in historical estimates of temperature, since NASA refined its data for the period 1930 to 1999, are biased toward global warming.

Steven Goddard, writing in The Register, analyzed two different NASA reports of historic temperature anomalies – published in 1999 and 2007 – and showed estimates for years in the 1930s through 1970 were lowered while estimates for years from 1970 to 1999 were increased between the two reporting periods. The results, when graphed, described a temperature regime that was cooler than previously thought prior to 1970 and warmer than thought since – precisely what advocates of global warming argue but what earlier renditions of the data did not say so clearly.

That, said Goddard, defied statistical odds.

U.S. Temparature Anomalies -- 2007 report
U.S. temperature anomalies — 2007 report

“So what is the probability of this effort consistently increasing recent temperatures and decreasing older temperatures? From a statistical viewpoint, data recalculation should cause each year to have a 50/50 probability of going either up or down – thus the odds of all 70 adjusted years working in concert to increase the slope of the graph are an astronomical 2 raised to the power of 70. That is one-thousand-billion-billion to one. This isn’t an exact representation of the odds because for some of the years (less than 15) the revisions went against the trend – but even a 55/15 split is about as likely as a room full of chimpanzees eventually typing Hamlet. That would be equivalent to flipping a penny 70 times and having it come up heads 55 times. It will never happen – one trillion to one odds (2 raised to the power 40).

“Particularly troubling are the years from 1986-1998. In the 2007 version of the graph, the 1986 data was adjusted upwards by 0.4 degrees relative to the 1999 graph. In fact, every year except one from 1986-1998 was adjusted upwards, by an average of 0.2 degrees. If someone wanted to present a case for a lot of recent warming, adjusting data upwards would be an excellent way to do it.

NASA is not the only source of long-term temperature data used to evaluate climate change. Like NASA, the UK Meteorological Office’s Hadley Center for Climate Studies depends on a network of ground-based weather stations using thermometers. Both are limited by their number of stations, the heat-island effects on many of the sites located in urban areas, changes in thermometer types over time and the loss of station sites over the historical periods being measured. Data gathered from these systems often has to be adjusted to remove “noise” caused by the local environment so it can be standardized for analysis.

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.

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.

As WND has previously reported 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.’ hottest year was in the past, 1936.

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