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Predicted long-term drought in the Horn of Africa

By Michael Evans - 15 Feb 2011 7:33:0 GMT
Predicted long-term drought in the Horn of Africa

Regular droughts have long been regarded as a feature of eastern Africa, but over the past 20 years the frequency of these droughts has noticeably increased. According to new research published in Climate Dynamics, this is likely to continue as global temperatures continue to rise.

If this prediction is correct it means that an estimated 17.5 million people in the Greater Horn of Africa are at risk of potential food shortages.

The predictions are the result of a study carried out by scientists from the US Geological Survey (USGS) and the University of California, Santa Barbara. They concluded that the increase in temperature of the Indian Ocean that caused decreased rainfall in eastern Africa was linked to global warming.

They believe that as the world warmed up during the last century, the Indian Ocean warmed up particularly fast. The warmer air rose, but the increased humidity produced more frequent rainfall in that region. Having lost most of its moisture the air then flowed westwards and descended over Africa, causing drought conditions in Kenya and Ethiopia.

This new research that indicates continued drought, contradicts previous scenarios made by the Intergovernmental Panel on Climate Change, which maintained that rainfall in eastern Africa would actually increase.

The USGS and the US Agency for International Development are anxious to identify areas of potential drought and famine in order to target food aid and to provide information on agricultural development, environmental conservation and the planning of water resources.

USGS scientist Chris Funk says that in view of the predicted increase in global temperatures it is anticipated that precipitation totals in Kenya and Ethiopia will continue to decrease or will remain below the historical average. This decrease in rainfall is particularly pronounced in the March to June season, he reports, when this is when substantial rainfall usually occurs. However, drought s not he only reason for food shortages; the development of agriculture has stagnated and population has continued to grow, so there are simply more mouths to feed.

Park Williams, a scientist from the University of California, Santa Barbara points out that forecasting the variability of precipitation from year to year is extremely difficult. Strong efforts are being made to improve reliability by linking global change and precipitation in specific regions. By doing this it is hoped that more accurate projections of future precipitations can be developed.

Park Williams also stresses that while sea temperatures in the Indian Ocean are expected to continue to rise, thus causing an average decrease in eastern African rainfall, since there are many other factors that influence precipitation, very wet seasons will still occur from time to time.

In order to arrive at their findings, scientists looked at data to see what was driving climate variations. Most of the Indian Ocean warming was found to be linked to human activities, particularly greenhouse gas and aerosol emissions. The Indian Ocean has warmed particularly fast because it is quickly being encroached upon by the Tropical Warm Pool, which is an area with the warmest ocean surface temperature in the world.