Up to one fifth of all warming reported across the planet by around 20,000 weather stations is invalid due to corruption from non-climatic data. This finding is the latest revelation from two atmospheric scientists seeking to measure the effect of human-caused urban heat on global surface temperature measurements. The news is sensational because it depresses further the major slowdown in warming observed since around 1998. With the global temperature warming by little more than 0.1°C over the last two decades, it makes claims of 4°C warming by the end of the century seem even more implausible.
The latest finding arises from the ongoing work of Dr. Roy Spencer and Professor John Christy of the University of Alabama in Huntsville. The two scientists looked at the 19,885 temperature stations in the Global Historical Climate Network (GHCN) distributed around the world from latitudes 20N to 82.5N. They found that over the last 40 years, virtually all of them had experienced growth associated with human settlement. The global work is said to be at an early stage, but “very preliminary calculations” are said to suggest that urban heat averaged across all stations is about 10-20% of GHCN trends.
Read more: Two Top Climate Scientists Find Further Evidence That Global Warming Has Been Exaggerated
