Long-term variability and trends in the Agulhas Leakage and its impacts on the global overturning

A positive correlation between the Agulhas Current and the Agulhas Leakage is shown, meaning that an increase of the Agulhas Current transport leads to an increase in Agulhas Leakage. The Agulhas Leakage impacts the strength of the AMOC through Rossby wave dynamics that alter the cross-basin geostrophic balance with a time lag of 2–3 years. Furthermore, the salt transport associated with the Agulhas Leakage influences AMOC dynamics through the salt–advection feedback by reducing the AMOC's freshwater transport at 34° S. The Agulhas Leakage transport indeed increases under a warming climate due to strengthened and southward-shifting winds.

In contrast, the Agulhas Current transport decreases due to a decrease in the Indonesian Throughflow and the strength of the wind-driven subtropical gyre. The increase in the Agulhas Leakage is accompanied by a higher salt transport into the Atlantic Ocean, which could play a role in the stability of the AMOC via the salt–advection feedback.