A meteor helps reveal West Africa's troubling drought history
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But the challenge, he continues, is that most of the big-ticket food aid the region has received has been aimed at farming for export, instead of food production for local consumption. As a result, food imports have grown. And efforts to improve resilience to drought have been piecemeal – what some have dubbed "a thousand points of green" – rather than a coordinated regionwide effort.Skip to next paragraph
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For aid agencies, as well as for local and regional officials, the paper represents a shot across the bows, suggests Mohamed Bakarr, a senior environment specialist at the Global Environment Facility in Washington. GEF is a multinational organization that helps finance projects that help developing countries meet their obligations under several international environmental treaties.
"We're not talking about small decisionmaking here," in response to what the climate can dish out, he says. The consequences of a drought on the scales Shanahan and colleagues have identified "will be catastrophic."
The study owes its scientific success to a meteor, which smacked into the African continent 1.07 million years ago in what is now Ghana. The crater filled with water to become Lake Bosumtwi, with a depth of 250 feet. Its bottom is deprived of dissolved oxygen, so nothing lives down there to stir up the muck. And the crater rim provides some shelter from winds that would stir things up. The result: a lake bottom consisting of neatly layered silt, each layer deposited by each year's seasonal monsoon.
The hunt for signals of dry and wet years led the scientists to look for changes in the concentration of minerals and metals in the lake-bottom sediment layers. During dry periods, lake levels fall. That exposes more of the crater rim to the erosive effect of any rain that does fall. So dry periods are marked by sediments containing high concentrations of aluminum, silica, potassium, calcium, titanium, and iron. With more rain, the lake level rises, reducing the rim's exposure and reducing the mount of metals and minerals in the sediment that form a new layer.
"It's a fantastic archive," Shanahan says.
Countries in the region have made some progress in learning the lessons of the last major drought, Dr. Bakarr says. After the drought in the Sahel in the 1970s and '80s, nine countries in the region formed the Interstate Committee for the Fight Against Drought in the Sahel. It's based in Ouagadougou, Burkina Faso, and focuses on developing sustainable approaches to farming and water use, as well as drought forecasting.
Bakarr notes that projects in the region are encouraging farmers to feed livestock in pens, rather than allowing them to graze open land and destroy vegetation – a factor in the desertification of the Sahel during the last major drought. Improved water-storage techniques, as well as encouraging farmers to plant trees in their fields to shade crops, are other arrows in the drought-resilience quiver
But in the face of droughts lasting a century or more, the arrows are likely to fall far short of their target.
The scale and magnitude of the preparations needed to deal with the region's now-clear drought patterns "require the kinds of investment to match what is happening in the health sector or in the food-security sector," Bakarr says. "The development community needs to see these kinds of calls as requiring major commitments and major investments, and not just a mere policy response."