[Illustrations, footnotes and references available in PDF version]
Global warming is one of the most serious issues of our times. Some experts claim the rise in temperature during the past century was “unprecedented” and proof that immediate action to reduce human greenhouse gas emissions must begin. Other experts say the warming was very modest and the case for action has yet to be made.
The reliability of data used to document temperature trends is of great importance in this debate. We can’t know for sure if global warming is a problem if we can’t trust the data.
The official record of temperatures in the continental United States comes from a network of 1,221 climate-monitoring stations overseen by the National Weather Service, a department of the National Oceanic and Atmospheric Administration (NOAA). Until now, no one had ever conducted a comprehensive review of the quality of the measurement environment of those stations.
During the past few years I recruited a team of more than 650 volunteers to visually inspect and photographically document more than 860 US temperature stations. We were shocked by what we found. The conclusion is inescapable: The U.S. temperature record is unreliable.