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Climate: Indian Ocean temps drive East African droughts

Study may unlocks new climate clues

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Wet conditions in coastal East Africa are associated with cool sea surface temperatures in the eastern Indian Ocean and warm sea surface temperatures in the western Indian Ocean, which cause ascending atmospheric circulation over East Africa and enhanced rainfall. (Courtesy Jessica Tierney, et al, 2013)

By Summit Voice

FRISCO — A new study may help forecast drought conditions in the oft famine-stricken and geopolitically crucial Horn of Africa. More than 40 million people in the region often live in exceptional drought conditions, most recently in 2010-2011, when the worst drought in decades triggered a humanitarian crisis.

It’s long been clear that El Niño can affect precipitation in the region, very little is known about the drivers of long-term shifts in rainfall. But the study suggests that temperatures in the Indian Ocean may be the key to understanding precipitation patterns in East Africa.

“The problem is, instrumental records of temperature and rainfall, especially in East Africa, don’t go far enough in time to study climate variability over decades or more, since they are generally limited to the 20th century,” said Woods Hole Oceanographic Institution geologist Jessica Tierney, lead author of the paper published in the journal Nature. Continue reading

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East Africa drought, famine linked to climate change

Young boys working in a newly cropped field in Africa. PHOTO COURTESY USGS.

Forecast calls for below average rains this spring and early summer

By Summit Voice

SUMMIT COUNTY— Spring rains in the eastern Horn of Africa are projected to begin late this year and yield less moisture than average, according to a study led by the U.S. Geological Survey. Long-term climate research shows that droughts around the Horn are linked with global warming, as the Indian and west-central Pacific have warmed faster than other areas, resulting more rain over the oceans, with drier air descending over east Africa.

“Rainfall projections were estimated by looking very closely at all the prior droughts from March–May since 1979 in the eastern Horn of Africa,” said USGS scientist Chris Funk, who led the research. “We found that sea surface temperatures in the western/central Pacific and the Indian oceans are key drivers of rainfall during that time period. So we compared sea surface temperatures from past years to March 2012, and developed an updated rainfall forecast for this spring season.”

Based on data from previous drought, the study concludes that, from March to May, the rains are expected to total only 60 to 85 percentage of the average rainfall in this region. This is a significant deterioration compared to earlier forecasts. Continue reading

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