World's Deserts are Expanding

Posted on May 25, 2006

China is not the only country that has to worry about desert creep. The AP reports that a new study has found the Earth's deserts are expanding. Here in the U.S. it means that the American Southwest deserts will get bigger.

Deserts in the American Southwest and around the globe are creeping toward heavily populated areas as the jet streams shift, scientists reported Thursday.

The result: Areas already stressed by drought may get even drier.

Satellite measurements made from 1979 to 2005 show that the atmosphere in the subtropical regions both north and south of the equator is heating up. As the atmosphere warms, it bulges out at the altitudes where the northern and southern jet streams slip past like swift and massive rivers of air. That bulging has pushed both jet streams about 70 miles closer to the Earth's poles.

Since the jet streams mark the edge of the tropics, in essence framing the hot zone that hugs the equator, their outward movement has allowed the tropics to grow wider by about 140 miles. That means the relatively drier subtropics move as well, pushing closer to places like Salt Lake City, where Thomas Reichler, co-author of the new study, teaches meteorology.

An article on ABC News says the study matches what some global-warming projections have shown.
If the trend continues through the end of the century, it would drive rain-bearing storms toward higher latitudes, deprive heavily populated southern Europe of much-needed winter rain and snow, and expand the world's subtropical deserts, atmospheric scientists say.

"It's a big deal," notes Thomas Reichler, a University of Utah atmospheric scientist and a member of the research team, which reported its results in Friday's issue of the journal Science.

Some aspects of the results are consistent with global-warming projections, team members note. If the cause does prove to be global warming, these results would represent the first direct satellite evidence of its impact on worldwide atmospheric circulation, says team leader Qiang Fu, a researcher at the University of Washington.

If the deserts are expanding then we have to learn to better manage our most precious resource: water.

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