A recent report by Richard Black on the BBC’s Science & Environment website is headed ‘West Africa faces ‘megadroughts’. Most climate sceptics who visit blogs like Harmless Sky will anticipate what is coming next – but in this case things aren’t quite so simple.
The article refers to a new research paper published in Science by a team from the University of Texas. They have been sampling sediments from Lake Bosumtwi in Ghana which indicate that this area is regularly subject to severe droughts which last not just for years, or even decades, but for centuries. The most recent one ended about 250 years ago, comfortably before human activity can be blamed for climate change.
Apparently the researchers are baffled about what causes these phenomena. Recurrent droughts lasting a decade of so are thought to be associated with variations in ocean currents, which in turn influence the intensity of rainfall. But these ‘megadroughts’ are on an altogether different scale and no explanation of the cause is being offered.
Such events should not be confused with the appalling drought in the Sahel during the 1970s and 1980s which is estimated to have claimed hundreds of thousands of lives.
Here is what one of the scientists has to say: Continue reading »
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