Science Update: Deserts

22 April 2007

Interview with

Chelsea Wald and Bob Hirshon

Bob -   This week for the Naked Scientists, we're going to talk about two deserts on opposite sides of the world. I'm going to tell you why scientists think the already dry American Southwest is drying out even more, but first, Chelsea has this report on a desert region in Africa that's been very much in the news.Drought - Sonora Desert, MexicoChelsea -   The war-torn Darfur region in Sudan was once home to an ancient mega-lake, and some of that water may still be there. Geologist Farouk El-Baz is director of the Boston University Center for Remote Sensing. He says satellite radar data show that thousands of years ago, Darfur was a savannah with a lake the size of the state of Massachusetts. His team is certain that deep wells could tap the remains of that lake.Farouk El-Baz (Boston University):  And the reason that we are absolutely convinced that this is the case is the fact that we do have a very similar structure just north of the area we're talking about, in the western desert of Egypt, and it has plenty of water. There are now 500 wells drilled through it, and there is potentially something like 150,000 acres of arable land, and the water that's available there could supply all of these acres for agriculture over 100 years.Chelsea -   Since the brutal conflict in Darfur is in part over water, there's hope that this new source could help bring peace. Bob -   Thanks, Chelsea. By mid-century, the American southwest and parts of northern Mexico may settle into a permanent drought: one that, for dryness, could rival the Dust Bowl in the Depression-era Great Plains, or the Southwest's own severe drought of the 1950's, the worst of the century.  This is from climatologist Richard Seager of Columbia University's Lamont Doherty Earth Observatory. He and his colleagues analyzed 19 different climate models used in the Intergovernmental Panel on Climate Change's Fourth Assessment Report. The data suggest that a drying trend has already begun in sub-tropical areas worldwide. Richard Seager (Lamont Doherty Earth Observatory):  It begins right at the junction of the 20th century and the 21st century.  So the models say that yes, this should already be underway. Bob -   Seager says that unlike past droughts, the current drying trend is caused by changes in air circulation due to global warming. A long-term drought would increase the strain on already-overtaxed water sources like the Colorado River.  That could force the region's rapidly growing population to re-evaluate its priorities.Richard Seager:  Throughout the Southwest, it's not people that are the main users of the water, but it's actually agriculture, even in desert states like Arizona... so, there's going to be some sort of difficult decisions that are going to have to be made about how the diminishing water resources get allocated. Bob -   He also notes that although there's probably nothing we can do to stop the drying trend completely, restricting greenhouse gas emissions may potentially limit just how bad it gets. Chelsea -   Thanks, Bob. We'll be back next time with stories about the things that profoundly influence your buying decisions like, of course, celebrities. Until then, I'm Chelsea WaldBob -   And I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists!

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