Benguela upwelling system triggered and intensified southern African aridification in the Late Miocene

Upwelling systems are critical drivers of regional climate variability, through their influence on ocean–atmosphere interactions and biogeochemical cycles. The Benguela Upwelling System, closely tied to Southern Ocean fronts and Indian-Atlantic water exchange, offers key insights into regional to global climatic shifts. This study analyses evolution of the Benguela Upwelling System during ~11.7 Ma–Holocene, using planktic foraminiferal relative abundance and oxygen and carbon stable isotope analysis from Ocean Drilling Program Site 1087. The data reveal unimpeded flow of Indian Ocean waters into the Southeast Atlantic before the onset of upwelling at ~10 Ma. The upwelling system was fully developed at ~9.8 Ma, which intensified between ~8.0 and 4.8 Ma, aided by strong southeast trade winds. The intense upwelling in Late Miocene Cooling interval triggered and intensified aridification in southern Africa. Upwelling and aridification became decoupled between ~4.8 and 3.7 Ma, coinciding with enhanced interoceanic exchange and the intrusion of warm Angola Current (Benguela Niño-like conditions). The reintensification of upwelling in the Plio-Pleistocene terminated Benguela Niño-like conditions and overshadowed signals of Indian Ocean inflow. Our findings underscore the pivotal role of the Benguela Upwelling System in regulating southern African climate and its linkages with the polar fronts. The Benguela upwelling system has played a key role in regulating southern African climate since the late Miocene, according to planktic foraminiferal relative abundance and stable isotope analyses from a site in the Benguela upwelling system.