“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 University of Arizona climatologist Jonathan Overpeck, a co-author of the study.
Overpeck and his colleagues studied sediments beneath Lake Bosumtwi in Ghana that gave an almost year-by-year record of droughts in the area going back 3,000 years. They found a pattern of decades-long droughts like the one that began in the Sahel in the 1960s — killing at least 100,000 people — as well as centuries-long “megadroughts”. The most recent lasted from 1400 to 1750, the researchers said.
“What’s disconcerting about this record is that it suggests that the most recent drought was relatively minor in the context of the west African drought history,” said Timothy Shanahan of the University of Texas, another co-author of the study.
The most recent decades of data from Lake Bosumtwi show that droughts there appear to be linked to fluctuations in sea surface temperatures, the researchers said. “One of the scary aspects of our record is how the Atlantic [Ocean] … changes the water balance over west Africa” on time scales lasting many decades, Overpeck told Reuters.
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