Anthony Watt has produced a report based on his excellent work at SurfaceStations.org document siting and installation issues at US surface temperature stations that might create errors and biases in the measurements.  The work is important, as these biases don’t tend to be random — they are much more likely to be upwards rather than downwards biases, so that they can’t be assumed to just average out.

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 0.7º C (about 1.2º 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.

I have performed about ten surveys for the effort, including three highlighted in the report (Gunnison, Wickenberg and the moderately famous Tucson site).  My son did two surveys, including one in the report (Miami) for a school science fair project.