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Summarised by Centrist
A new study from the University of Alabama in Huntsville researcher John Christy claims both hot and cold temperature extremes across the contiguous United States have declined since 1899.
The study analysed “more than 40 million daily temperature observations” from 1,211 weather stations, aiming to provide what the article calls “the most complete long-term view to date of US extreme heat and cold”.
Christy said building the dataset “was a labour of love and curiosity”.
The study found “extreme summer heat has not increased”, with the hottest annual temperatures, daily heat records and heatwave days showing “modest declines since 1899”.
It also found “extreme cold has decreased sharply”, especially since the 1990s.
Overall, the article says “extremes have become less extreme”, with the gap between the hottest and coldest annual temperatures narrowing by about 6°F over the full record.
Notably, western US regions have seen more heatwave activity in the past decade, while central and eastern regions show long-term declines.
Christy said, “Understanding how extremes have changed over time is essential for interpreting (dispassionately) how today’s events actually compare with the past.”
