One of the most invaluable resources backing this particular angle has been Anthony Watts's blog and, more importantly, his Surface Stations website. This latter is an effort to harness people, all over the US, to survey the temperature stations that feed into the US temperature record.
Now, via Climate Skeptic, I see that Anthony Watts has a full report [PDF] over at The Heartland Institute—I haven't yet read this in full, but the summary is crystal clear.
We found stations located next to the exhaust fans of air conditioning units, surrounded by asphalt parking lots and roads, on blistering-hot rooftops, and near sidewalks and buildings that absorb and radiate heat. We found 68 stations located at wastewater treatment plants, where the process of waste digestion causes temperatures to be higher than in surrounding areas.
In fact, we found that 89 percent of the stations—nearly 9 of every 10—fail to meet the National Weather Service’s own siting requirements that stations must be 30 meters (about 100 feet) or more away from an artificial heating or radiating/ reflecting heat source.
In other words, 9 of every 10 stations are likely reporting higher or rising temperatures because they are badly sited. It gets worse. We observed that changes in the technology of temperature stations over time also has caused them to report a false warming trend. We found major gaps in the data record that were filled in with data from nearby sites, a practice that propagates and compounds errors. We found that adjustments to the data by both NOAA and another government agency, NASA, cause recent temperatures to look even higher.
The conclusion is inescapable: The U.S. temperature record is unreliable. The errors in the record exceed by a wide margin the purported rise in temperature of 0.7° C (about 1.2° F) during the twentieth century. Consequently, this record should not be cited as evidence of any trend in temperature that may have occurred across the U.S. during the past century. Since the U.S. record is thought to be “the best in the world,” it follows that the global database is likely similarly compromised and unreliable.
If we are unable to measure reliably the temperature in the US, then how are we supposed to be able to perform a global temperature measurement? Especially when the majority of the Earth's surface area is water?
The answer is, of course, that we cannot: and if we cannot reliably measure the world's temperature, then we cannot make any reliable assertions about anthropogenic climate change. We certainly cannot make any assertions reliable enough to be worth beggaring the planet for.
This report will be one of the final nails in the coffin of AGW. Unfortunately, as per fucking usual, it will take the politicians about a decade to catch up...