Abstract/Summary

Eastern Africa experiences extreme rainfall variations that have profound socio-economic impacts. In this Review, we synthesize understanding of observed changes in seasonal regional rainfall, its global to local forcings, the expected future changes and the associated environmental impacts. We focus on regions where annual bimodal rainfall is split between long rains (March-May) and short rains (October-December). Since the early 1980s, the long rains have got drier although some recovery is observed in 2018 and 2020 (-0.12—1.23 mm/season/decade). Meanwhile, the short rains have got wetter (1.27—2.58 mm/season/decade). These trends, overlaid by substantial year-to-year variations, impact the severity and frequency of extreme flooding and droughts, the stability of food and energy systems, the susceptibility to water-borne and vector-borne diseases and ecosystem stability. Climate model projections of rainfall changes vary but there is some consensus that a warming climate will increase rainfall over Eastern Africa. They suggest that by 2030-2040 the short rains will deliver more rainfall than the long rains, which has implications for sustaining agricultural yields and triggering climate-related public health emergencies. Mitigating the impacts of future Eastern African climate requires continued investments in agriculture, clean water, medical and emergency infrastructures that are commensurate to the upcoming existential challenges.