African droughts linked to warming Indian Ocean

Posted by Laura Grant on August 8, 2008
Posted in Green News

Sea surface temperatures and land vegetation over the Indian Ocean in a visualization created with satellite data. Credit: NASA

Scientists have found a link between rising temperatures in the Indian Ocean and the decreases in rainfall over eastern and southern Africa. Records show that rainfall during eastern Africa’s rainy season (March to May) has decreased by 15 percent since the 1980s.

“The last 10 to 15 years have seen particularly dangerous declines in rainfall in sensitive ecosystems in East Africa, such as Somalia and eastern Ethiopia,” said Molly Brown of NASA’s Goddard Space Flight Center, a co-author of the study published in the Proceedings of the National Academy of Sciences. “We wanted to know if the trend would continue or if it would start getting wetter.”

The scientists analysed historical rainfall data over both the Indian Ocean and Africa’s eastern seaboard between 1950 to 2005. They found that declines in rainfall in Ethiopia, Kenya, Tanzania, Zambia, Malawi and Zimbabwe were linked to increases in rainfall over the ocean.

Results obtained from combining the historical data with computer modelling strongly suggested that  warming of the Indian Ocean led to an increase in rainfall over the ocean which could then create a weather pattern that reduced the flow of moisture onshore., bringing dry air down over the African continent, Nasa reports.

Rainfall over the ocean could continue to incease until 2050, the report says. Lead author Chris Funk of the University of California, Santa Barbara was quoted as saying, “This 15 percent decrease [in rainfall over eastern Africa] every 20-25 years is likely to continue.”

The decline in rainfall could have a very serious impact on agriculture in the region, the report says.

Via :: Terra Daily and Nasa


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