Parts of the southern U.S. could face drier conditions
SUMMIT COUNTY — Global warming alone doesn’t account for a startlingly rapid northward expansion expansion of the tropics in the northern hemisphere, according to a new study from the University of California, Riverside.
It appears that black carbon aerosols and tropospheric ozone, both manmade pollutants emitted predominantly in the Northern Hemisphere’s low- to mid-latitudes, are also significant factors, and perhaps the primary drivers in the changes.
Observations show that the tropics have widened by 0.7 degrees latitude per decade, with warming from greenhouse gases also contributing to the expansion in both hemispheres.
“If the tropics are moving poleward, then the subtropics will become even drier,” said UC Riverside climatologist Robert J. Allen. “If a poleward displacement of the mid-latitude storm tracks also occurs, this will shift mid-latitude precipitation poleward, impacting regional agriculture, economy, and society,” said Allen, an assistant…
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