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.