Killer Droughts are the Norm in West Africa, Study Finds

Results of a study conducted by scientists at the University of Arizona and University of Texas in the US revealed that the severe droughts lasting several decades, even centuries, have happened often in West Africa's recent history.

Timothy Shanahan and colleagues studied sediments from Lake Bosumtwi in Ghana and found out that the megadrought that killed more than 100,000 thousand people in Africa's Sahel region was caused by the natural climate cycle. The drought in the Sahel, a semi-arid region that extends from Senegal eastward to Sudan, was believed to have been caused by human activities. The scientists believe the droughts are driven in part by circulation of the ocean and atmosphere in and above the Atlantic.

Climate change could bring more disastrous drought in the region, the researchers warned. Sediment records that stretch back more than three millennia suggest that the most recent drought was relatively minor in the context of the West African drought history. "If we were to switch into one of these century-scale patterns of drought, it would be a lot more severe, and it would be very difficult for people to adjust to the change," Shanahan noted.

For more information, read http://www.nsf.gov/news/news_summ.jsp?cntn_id=114583&org=NSF&from=news Subscribers to the journal Science can download the full paper at http://dx.doi,org/10.1126/science.1166352