Dust Bowl 2: Drought detective predicts
drier future for American Southwest
Water managers in the Southwest seem to be paying attention, and even taking action. "They understand that it's going to get drier," says Seager. "So it is probably not a good idea for them to sit around and wait until our models get better."
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It would seem no one is actually listening to Perry’s prayers because the only alternative would be to believe that whoever is listening is doing the exact opposite of what Perry has prayed for. As the latest U.S. Drought Monitor shows, the Texas drought is considerably worse than when Perry issued an official proclamation drawing on his constitutional authority designating three days as Days of Prayer for Rain back in April . . .
By Seth Shulman | Grist
Published August 2010
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If you're one of the tens of millions of people who live in the southwestern United States, get ready for drier weather. That's the message from Richard Seager, a climate scientist at Columbia University's Lamont-Doherty Earth Observatory. The American Southwest, says Seager, is soon likely to experience a "permanent drought" condition on par with the Dust Bowl of the 1930s.
The Hadley Cell is growing – that Creator of Deserts, that driver of the Horse Latitudes ... but it's NOT the only Climate-driver changing its non-beneficial behavior of late
That rather frightening prediction is the most likely scenario for the region, given the global warming now underway. "It is a matter of simple thermodynamics," says Seager. "The region will face a considerable increase in aridity over the coming decade."
The Southwest is as dry as it is because the local atmospheric flow tends to export far more moisture than storms can carry into the region. This is the case in other parts of the so-called subtropics, those areas directly north and south of the equatorial tropics. But as earth's atmosphere becomes laden with heat-trapping greenhouse gases, it will be able to retain even more moisture. That means more evaporation from lakes and rivers, more moisture loss from plants, and drier soil.
A critical player in this drying cycle is the planetary-scale circulation system known as the "Hadley cell." This vast atmospheric system links rising air near the Equator with descending air in the subtropics, giving rise to the subtropical jet streams.
In the northern hemisphere the jet stream flows west to east across North America. Rising moist air condenses and forms thunderstorms in the tropics, but the moisture is largely lost by the time the air descends at subtropical latitudes. That's why most of the world's deserts are situated in the subtropics.
Seager recognizes that the stakes of his drought research are high. "The prospect of a drought on par with the 1930s is a matter of serious concern," he says. "With some two million people displaced, the Dust Bowl was probably the worst environmental disaster in the nation's history -- even counting the current oil spill in the Gulf."
Seager is quick to add, however, that many features of the Dust Bowl are unlikely to be repeated. For one thing, he says, "we have learned an awful lot about soil conservation since the 1930s."
Seth Shulman has worked for more than 25 years as a writer and editor specializing in issues in science, technology and the environment. A graduate of Harvard University, he has written five books and hundreds of articles for magazines including Smithsonian, The Atlantic, Parade, Discover, Rolling Stone, Popular Science, The Chronicle of Higher Education, The Progressive, and Time, and for newspapers including the Times of London, The Boston Globe, and The Los Angeles Times.