The Congo Air Boundary (CAB) is a zone of atmospheric convection crossing tropical East Africa in a southwest to northeast direction, and the boundary between air flows from the Atlantic Ocean in the west and the Indian Ocean in the east. As the behaviour of these moisture sources can vastly
differ, so too does rainfall on both sides of the CAB. Despite the CAB being a major climate transition zone impacting many millions of people depending on rain-fed agriculture, its dynamics and drivers have never been studied in depth. This is a major knowledge gap, since recent observations suggest that anthropogenic climate change is affecting the stability of the CAB, complicating forecasts of future rainfall over East Africa. This project will thoroughly investigate past shifts of the CAB over East Africa on multiple time scales throughout the last c. 20,000 years. Climate histories will be reconstructed at several key locations across East Africa, using climate-change indicators in lake sediments. For the period AD 1800-present, these will be supplemented with historical and instrumental rainfall data. These new local climate histories will be integrated with existing data into state-of-the-art information networks of past climate change at the regional scale, and compared to climate-model simulations to elucidate when, how and why the CAB has migrated through time and how this has affected East-African rainfall and drought regimes.