Urbanization Effects on GHCN Temperature Trends, Part II: Evidence that Homogenization Spuriously Warms Trends
February 7th, 2023 by Roy W. Spencer, Ph. D.
In Part I I showed the Landsat satellite-based measurements of urbanization around the Global Historical Climate Network (GHCN) land temperature-monitoring stations. Virtually all of the GHCN stations have experienced growth in the coverage of human settlement “built-up” (BU) structures.
As an example of this growth, here is the 40-year change in BU values (which range from 0 to 100%) at 1 km spatial resolution over the Southeast United States.
Fig. 1. The 40-year change in urbanization over the Southeast U.S. between 1975 and 2014.
How has this change in urbanization been expressed at the GHCN stations distributed around the world? Fig. 2 shows how urbanization has increased on average across 19,885 GHCN stations from 20N to 82.5N latitude, at various spatial averaging resolutions of the data.
https://www.drroyspencer.com/2023/02/urbanization-effects-on-ghcn-temperature-trends-part-ii-evidence-that-homogenization-spuriously-warms-trends/
