Projected changes in extreme precipitation in Africa under global warming, Part II: East Africa

Abstract Probable changes,in mean,and extreme,precipitation in East Africa are estimated from global climate models,prepared for the IPCC Fourth Assess- ment Report (AR4). Bayesian statistics are used to derive the relative weights assigned to each member,in the multi-model ensemble. There is substantial evidence in support of a positive shift of the whole rainfall distribution in East Africa during the wet seasons. The models,give indications for an increase in mean precipitation rates and intensity of high rainfall events, but less severe droughts. On top of the general increase in rainfall in the tropics due to thermody- namic effects, differential warming in the tropical Indian Ocean in the future climate during boreal autumn,is favourable for an enhanced,probability of pos- itive Indian Ocean Zonal Mode (IOZM) events. This is physically consistent with reduced,return periods of excessive short-rains in East Africa. 2