On the role of the Agulhas system in ocean circulation and climate

Checking the flow through the Agulhas leakage The Agulhas current system around South Africa forms a key component of the global thermohaline ocean circulation. Through what is known as the Agulhas leakage, the current injects warm, salty Indian Ocean waters into the Atlantic Ocean. Unlike processes in the North Atlantic, the leakage has received little attention from researchers. In this Review, Beal and colleagues assemble the available palaeo and modern climate research and demonstrate that the Agulhas current has a strong role in ocean circulation and climate as well as a potential role in stabilizing the Atlantic Meridional Overturning Circulation. The Atlantic Ocean receives warm, saline water from the Indo-Pacific Ocean through Agulhas leakage around the southern tip of Africa. Recent findings suggest that Agulhas leakage is a crucial component of the climate system and that ongoing increases in leakage under anthropogenic warming could strengthen the Atlantic overturning circulation at a time when warming and accelerated meltwater input in the North Atlantic is predicted to weaken it. Yet in comparison with processes in the North Atlantic, the overall Agulhas system is largely overlooked as a potential climate trigger or feedback mechanism. Detailed modelling experiments—backed by palaeoceanographic and sustained modern observations—are required to establish firmly the role of the Agulhas system in a warming climate.