Here's one for the more climate contrarian people among TreeHugger's readership: A new study published in the Journal of Geophysical Research - Atmospheres shows that Anthony Watts and SurfaceStations.org was indeed correct. There are indeed a good deal of poorly-placed weather monitoring stations in the United States. And these have caused a bias in the record of temperature changes:Except that when the researchers at the National Climatic Data Center examined what sort of bias these weather stations were introducing into the record--and it should be mentioned that these sort of instrument issues have been long acknowledged as being real--they found that these stations induced a slightly cool bias, not a warm one as Watts, et al. claim.
But here's the gist of how the analysis was done, from the former source:
Dr. Menne's study split the U.S. surface stations into two categories: good (rating 1 or 2) and bad (ratings 3, 4 or 5). They performed the analysis using both the rating provided by surfacestations.org, and from an independent rating provided by NOAA personnel. In general, the NOAA-provided ratings coincided with the ratings given by surfacestations.org. Of the NOAA-rated stations, only 71 stations fell into the "good" siting category, while 454 fell into the "bad" category. [...]
Dr. Menne's study computed the average daily minimum and maximum temperatures from the good sites and poor sites. The results were surprising. While the poor sites had a slightly warmer average minimum temperature than the good sites (by 0.03°C), the average maximum temperature measured at the poor sites was significantly cooler (by 0.14°C) than the good sites. As a result, overall average temperatures measured at the poor sites were cooler than the good sites. This is the opposite of the conclusion reached by Anthony Watts in his 2009 Heartland Institute publication.
Here's the original paper: On the reliability of the US Surface Temperature Record [PDF]
Global Warming Science
Aerosols More Important to Global Warming Than Acknowledged
NASA Makes It Official: 2000-2009 Was Hottest Decade on Record
Decreased Water Vapor in Atmosphere Slowed Last Decade's Warming