Remember all those news reports claiming this past summer was the hottest on record? And how it all was due to climate change?
Well, it certainly was a hot one in the southwest and other regions. It’s true that the city of Phoenix suffered several weeks of temperatures over 100 degrees, but that’s not the whole story.
While central Phoenix had the warmest summer in 90 years, Professor Roy Spencer and his colleague Professor John Christy took the official surface temperature data for the centrally located Sky Harbor Phoenix Airport and compared it to all rural stations within 5 to 60 miles of Phoenix. They concluded that if you factor out the urban heat island effect caused by the concrete jungle that is now Phoenix, last summer was only the 11th warmest on record in the area.
Both Spencer and Christy are climate scientists at the University of Alabama at Huntsville, and Christy has been Alabama State Climatologist since 2000.
“Cities are hotter than their rural surroundings, and increasingly so, with or without climate change,” Spencer says. “Most of what we hear through the media comes from urban reporting stations, or at least airports serving major urban areas.”
That can lead to measurements of extra warmth of up to 10 degrees, mostly at night.
In their new paper, they look at temperature data across the lower 48 States using satellite maps and data to compute how temperatures change with population density across thousands of closely spaced pairs of weather stations. They conclude that summer warming between 1895 and 2023 in the U.S. is only half as large as the official (but flawed) temperature reports. This past summer was only the 13th warmest in the record if adjusted for the effect of urbanization.