'Mega-droughts' forecast for Africa

Severe droughts could devastate sub-Saharan Africa following a recent decades-long drought that killed 100,000 people in Africa's Sahel region, scientists say.Sub-Saharan Africa often suffers droughts, but the group of specialists reported on Thursday that global climate change will make these dry periods more severe and more difficult for the people who live there.The prediction is contained in a study published in the journal of Science by the scientits at the University of Arizona, US."Clearly, much of West Africa is already on the edge of sustainability, and the situation could become much more dire in the future with increased global warming," said Jonathan Overpeck, a climatologist and co-author of the study.Temperatures in the Sahel region are expected to rise by five to 10 degrees this century, the scientists said, despite some curbing of the greenhouse emissions that cause climate change."We might actually proceed into the future ... we could cross a threshold driving the [climate] system into one of those big droughts without even knowing it's coming," Overpeck said.