On Wednesday, the Heartland Institute gave evidence for such suspicions, when it released a new study entitled "Corrupted Climate Stations: The Official U.S. Surface Temperature Record Remains Fatally Flawed."

The study was authored by Anthony Watts, a senior fellow for environment and climate at The Heartland Institute and the creator of the climate-realism website Watts Up With That; and Dr. H. Sterling Burnett, director of the Arthur B. Robinson Center on Climate and Environmental Policy.

The study found that "approximately 96 percent of U.S. temperature stations used to measure climate change fail to meet what the National Oceanic and Atmospheric Administration (NOAA) considers to be 'acceptable' and uncorrupted placement by its own published standards."

NOAA's own standards call for temperature measuring to be done "Over level terrain (earth or sod) typical of the area around the station, and, at least 100 feet from any extensive concrete or paved surface."

NOAA claimed that it had cleaned up its United States Climate Reference Network (USCRN) data-collecting sites but in 2014 switched to another data set called "nClimDiv." The "nClimDiv" data included all of the USCRN data, along with thousands of other data-collection locations, many of which were beset with the same heat-adding biases.