Thursday, April 16, 2009

UA team finds African mega-droughts are normal

Over the pat 3,000 years, catastrophic droughts occurred every 30 to 65 years in parts of Africa, and the pattern can be expected to continue in the future, according to a new University of Arizona-led study to be published in Science tomorrow (Friday, Apr 17). In addition, some droughts can last centuries, with the last one running from 1400 - 1750 A.D. Climate changes are expected to worsen the situation.

We were at the same table at the Udall Foundation dinner tonight with Jonathan Overpeck, one of the authors of the study, "Atlantic forcing of persistent drought in West Africa," and his wife and co-author Julia Cole . Paleoclimatologist Brad Udall, son of former congressman Mo Udall, hailed the pair's work. The story is being featured in tomorrow's New York Times as well.

The team laid out the region's past climate by analyzing the annual layers of sediment deposited in Ghana's Lake Bosumtwi, geological records of the lake level and other climate indicators.

[right, UA researcher Winston Wheeler collects tree cores from a tree partially submerged in Lake Bosumtwi, Ghana. This tree grew at a time of prolonged drought when the lake level was tens of meters lower than today. Credit: Jonathan T. Overpeck]

Note: some of this post is taken from the UA news release.

Ref: Science 17 April 2009: Vol. 324. no. 5925, pp. 377 - 380
DOI: 10.1126/science.1166352

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