East African Drought Prediction and Humanitarian Responses in 2012

Long rains during the March-April-May (MAM) 2011 growing season were a failure for much of the Greater Horn of Africa. These conditions resulted in severe food shortages, with the Famine Early Warning Systems Network (FEWS NET) estimating that 12.4 million people were in need of food assistance in Kenya, Somalia, Ethiopia and Djibouti. Heading into the 2012 season, La Niña conditions, an exceptionally strong western-to-central Pacific sea surface temperature (SST) gradient, and warm SSTs in the eastern Indian Ocean foretold further dryness, compounding the difficulties faced by the already vulnerable populations of this region.

In this talk, we describe recent research that effectively characterizes seven out of eight of the most recent east African MAM droughts. This work can help us predict boreal water deficits in one of the most food insecure regions in the world. Using reanalysis and sea surface temperature data, we portray characteristic drought-creating Indo-Pacific climate conditions, and explain how these patterns were associated with a FEWS NET climate forecast and alert in March, 2012 that helped motivate the allocation of an additional $50M in food aid from the U.S. government.

We conclude with a brief discussion linking our forecast efforts to the El Niño-Southern Oscillation and low frequency warming patterns associated with increases in Warm Pool water vapor and absorbed longwave radiation. We show that a stronger than usual western-to-central Pacific SST gradient, combined with La Niña conditions, is particularly conducive to east African droughts. Warming in the western Pacific, and more frequent western-to-central Pacific SST gradient events, appear strongly connected to anthropogenic increases in water vapor and absorbed longwave radiation. We conclude with a brief examination of the persistence and lagged interrelationships of Warm Pool climate variables, and discuss the associated potentials for the enhanced predictability of drought in Africa, Asia and the United States.