The widespread use of regularly adjusted global and local surface temperature datasets showing increasingly implausible rates of warming has been dealt a further blow with new groundbreaking research that shows 50% less warming over 50 years across the eastern United States. The research attempts to remove distortions caused by increasing urban heat and uses human-made structure density data over 50 years supplied by the Landsat satellites. The 50% reduction in the warming trend is by comparison with the official National Oceanic and Atmospheric Administration (NOAA) homogenised surface temperature dataset.
The research was compiled by two atmospheric scientists at the University of Alabama in Huntsville, Dr. Roy Spencer and Professor John Christy. They used a dataset of urbanisation changes called ‘Built-Up’ to determine the average effect that urbanisation has had on surface temperatures. Urbanisation differences were compared to temperature differences from closely spaced weather stations. The temperature plotted was in the morning during the summertime. A full methodology of the project is shown here in a posting on Dr. Spencer’s blog.
Dr. Spencer believes that the ‘Built-Up’ dataset, which extends back to the 1970s, will be useful in ‘de-urbanising’ land-based surface temperature measurements in the U.S. as well as other countries. All the major global datasets use temperature measurements from the Integrated Surface Database (ISD), and all have undertaken retrospective upward adjustments in the recent past.