East African long rains declined abruptly



In 2010–2011 the East African region suffered a severe drought that affected millions of people. The drought was a consequence of the failure of both the seasonal “short rains,” which typically run from October to December, and the following “long rains,” which typically run from March to May. The failure of the short rains was predictable given a well-established connection with La Niña, but the failure of the long rains was not. In a new study, Lyon and DeWitt show that the most recent long rains failure is consistent with a recurrent large-scale precipitation pattern that began with an abrupt shift around 1999. The authors used observations and climate model simulations to show that the abrupt decline in the East African long rains was linked to similarly abrupt changes in sea surface temperatures, mainly in the tropical Pacific basin. (Geophysical Research Letters, doi:10.1029/2011GL050337, 2012) —EB