Southern Hemisphere subtropical front impacts on Southern African hydroclimate across the Mid-Pleistocene Transition.

Southern African (SA) hydroclimate is largely shaped by the interactions of atmospheric circulations, e.g., Hadley Circulation, and oceanic elements, like the Benguela Upwelling System (BUS), Agulhas System, and Antarctic Circumpolar frontal system. Large-scale changes to the Meridional Temperature Gradient (MTG) influence both the atmospheric and oceanic components of the hydroclimate system, and thus impact hydroclimate over SA. We present a leaf wax hydroclimate record from ODP 1084, in the BUS, which reveals that changes in the isotopic signature of precipitation over SA coincide with a strengthening of the MTG across the Mid-Pleistocene Transition (MPT). We use HadCM3 simulations to demonstrate the sensitivity of winter rainfall to shifts in the MTG during the MPT. Given the ongoing impacts of climate change on water resources in SA, awareness of the relationship between rainfall and shifts in Hadley Circulation could provide insight into past water availability and aid regional adaptation efforts.