Like other climate scientists, he knew from research papers and worldwide storm patterns that a warming atmosphere is thirstier and sops up more moisture from oceans and the land.
“But, in the Southwest, we've seen the exact opposite happening,” said Williams, an associate professor in the University of California, Los Angeles’ geography department. “For the last 50 or so years, we've actually seen the amount of water vapor molecules in the atmosphere decline” while temperatures have climbed about twice as fast as the global average.
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new paper from UCLA researcher Karen McKinnon largely solved that puzzle by showing the hottest days in the summer months are getting dramatically drier as a result of the Southwestern spring heating up and leaving less moisture behind to cool the summer through evaporation.