NASA, GISS and James Hansen have been busted before (by amateurs) for being wrong several times :
Deja Vu All Over Again: Blogger Again Finds Error in NASA Climate Data
NASA'S Goddard Institute for Space Studies (GISS) is one of the world's primary sources for climate data. GISS issues regular updates on world temperatures based on their analysis of temperature readings from thousands of monitoring stations over the globe.
GISS’ most recent data release originally reported last October as being extraordinarily warm-- a full 0.78C above normal. This would have made it the warmest October on record; a huge increase over the previous month's data.
Those results set off alarm bells with Steve McIntyre and his gang of Baker Street irregulars at Climateaudit.org. They noted that NASA's data didn't agree at all with the satellite temperature record, which showed October to be very mild, continuing the same trend of slight cooling that has persisted since 1998. So they dug a little deeper.
An alert reader on McIntyre's blog revealed that there was a very large problem. Looking at the actual readings from individual stations in Russia showed a curious anomaly. The locations had all been assigned the exact temperatures from a month earlier-- the much warmer month of September. Russia cools very rapidly in the fall months, so recycling the data from the earlier month had led to a massive temperature increase.
A few locations in Ireland were also found to be using September data..
Steve McIntyre informed GISS (run by Hansen) of the error by email. According to McIntyre, there was no response, but within "about an hour", GISS pulled down the erroneous data, citing a "mishap" and pointing the finger of blame upstream to the National Oceanic and Atmospheric Administration (NOAA)."
http://www.dailytech.com/Article.aspx?newsid=13410&red=y#366381
NOAA has been singled out for calling 2010 the warmest year using faulty data
NOAA’s Jan-Jun 2010 Warmest Ever: Missing Data, False Impressions
http://wattsupwiththat.com/2010/07/17/noaas-jan-jun-2010-warmest-ever-missing-data-false-impressions/