S. Africa Study Sounds Alarm on Climate Change
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Climate forecasts for later this century suggests that many parts of Africa could use lose precious rainfall as the planet warms. A study being published online by Science Magazine today suggests the loss of rainfall could lead to even more dramatic reductions in stream flow, and that could make life harder for people and wildlife alike.
NPR's Richard Harris has the story.
RICHARD HARRIS reporting:
The South African geologist who conducted the study didn't set out to take on the issue of climate change in the future of Africa's water supply. In fact, Martin Devitt at the University of Cape Town was actually doing some research for the diamond company, De Beers.
Mr. MARTIN DEVITT (University of Cape Town): They obviously are interested in diamond deposits throughout Africa. And one of the things that we do for them is to decide, well this is a good area, this is a bad area. That's the sort of research arena I'm in.
HARRIS: As part of that research, Devitt decided to survey all the big river systems in Africa. In the course of doing this, he noticed a striking pattern. In many cases, he found a mathematical relationship between the total length of streams in an area and the amount of rainfall. Rain didn't just make streams bigger, it made more of them and in a predictable pattern.
He was stunned to realize that this led directly to a much bigger question than just where to find diamonds.
Mr. DEVITT: Once we had that amazing relationship of present day Africa, we asked the obvious question, is, well, how will that change with the climate change models that are around?
HARRIS: Devitt combined the results of 21 different projections of rainfall in Africa for the year 2070 and beyond. He then asked how the stream networks would change as a result throughout the continent.
Mr. DEVITT: Well, we found some pretty drastic changes, for example, in the Cape area, which happens to be the area where I live.
HARRIS: If rainfall decreases by 20 percent, as some climate models predict, the extent of stream networks around Cape Town would decrease by more than 40 percent he found. And most of Africa is projected to see less rainfall. So the pattern could lead to widespread stream losses.
Mr. DEVITT: In the rural areas particularly, where large areas of Africa are dependent on riverbeds for their daily use of water, these are going to be major impacts.
HARRIS: People who now need to walk a mile to find a stream for water may have to walk a lot farther to find running water, he says. Now, this assumes that rainfall will decrease throughout Africa. Projections are uncertain though.
Jim Hurrell, a climate forecaster at the National Center for Atmospheric Research says, even so it is clear that current warming has already spread droughts throughout parts of Africa.
Mr. JIM HURRELL (National Center for Atmospheric Research): These are often in regions where water is a scarce resource to begin with. So this has tremendous socioeconomic implications for the people of Africa. And it becomes absolutely critical that we continue to study this, continue to understand what future climate change is likely to bring to those parts of the world.
HARRIS: And other scientists say the human impacts may not be the worst of it. Bill Dietrich is a geologist at the University of California at Berkeley.
Mr. BILL DIETRICH (University of California Berkeley): The ecological implications of this are enormous, if their analysis is even vaguely correct, because these small streams that are the tendrils of water through the landscape are the lifelines for the ecosystem, not just the things that live in the water, but the things that need to have water. As anybody who has watched wildlife films from Africa have seen, animals during the dry season collect where there is water.
HARRIS: Dietrich says this is the first study of its kind. As such, there are many unanswered questions that make the conclusions uncertain above and beyond the forecast of future rainfall. For his part, South African researcher Martin Devitt says he had no social or political ideals in his head when he set out to do this research project.
Mr. DEVITT: Now that it's on paper, I realize, wow, this is really part and parcel of a very big message to politicians in Africa that we are really going to have to seriously think about our river basin management in a different way.
HARRIS: Devitt says the research did not end up helping De Beers discover new diamond deposits, but the results could still be useful to his sponsor. Diamond mines, after all, need lots of water, so De Beers will need to think about the fate of Africa's water supply as it considers its own economic future.
Richard Harris, NPR News.
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