Environment Counts | Decreased rainfall in eastern Africa is linked to climate change
Author: Geoff Zeiss – Published At: 2011-07-18 23:05 – (767 Reads)
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A new study finds that decreased rainfall in eastern Africa is linked to climate change and is likely to continue. The warming of the Indian Ocean in recent decades has led to a decline in precipitation. With global temperatures continuing to rise, this trend of increased drought frequency will likely persist. According to the U.S. Geological Survey, these findings differ from those published by the United Nations International Panel on Climate Change (IPCC) in 2007, which projected an increase in rainfall based on earlier published research.
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An estimated 17.5 million people are food insecure in Kenya, Ethiopia, and Somalia, and the US government has spent over $1.1 billion on food aid in these countries since 2009.1 Food balance modeling suggests that this insecurity stems (in part) from stagnating agricultural development, population growth, and recent drought (Funk et al. 2008; Funk and Brown 2009); which has been linked to humancaused warming in the Indian Ocean (Funk et al. 2005, 2008; Verdin et al. 2005). This warming appears to have had a large impact on eastern African rainfall from March to June (MAMJ, Funk et al. 2008; Funk and Verdin 2009).
This season is known as the ‘long rains’ in Kenya and the ‘Belg’ rains in Ethiopia. In this paper, we show that a suite of observational datasets indicate a westward extension of the tropical warm pool into the Indian Ocean during MAMJ; this extension appears to be extending the zonally overturning atmospheric Walker circulation in a westward direction. While there appear to be many factors that govern interannual variability in east African long-rains precipitation, convective activity during MAMJ has steadily declined in eastern Africa for the past 30 years as the convective branch of the Walker circulation has become more active over the Indian Ocean.
This season is known as the ‘long rains’ in Kenya and the ‘Belg’ rains in Ethiopia. In this paper, we show that a suite of observational datasets indicate a westward extension of the tropical warm pool into the Indian Ocean during MAMJ; this extension appears to be extending the zonally overturning atmospheric Walker circulation in a westward direction. While there appear to be many factors that govern interannual variability in east African long-rains precipitation, convective activity during MAMJ has steadily declined in eastern Africa for the past 30 years as the convective branch of the Walker circulation has become more active over the Indian Ocean.
