Non-monotonic responses of Atlantic Meridional Overturning Circulation to Antarctic meltwater forcing

Antarctic meltwater discharge has been largely emphasized for its potential role in climate change mitigation, not only by reducing global warming, but also by stabilizing the Atlantic Meridional Overturning Circulation (AMOC). Despite the tremendous impact of the AMOC on the climate system, its temporal evolution to the meltwater remains poorly understood. In this study, we conduct idealized experiments to investigate the response of AMOC to Antarctic meltwater and discover a non-monotonic response of AMOC to the meltwater-induced cooling. Cold ocean surface caused by meltwater spread throughout the globe and eventually strengthened the AMOC. However, in the early stages, the tropical temperature response could stimulate the Rossby wave teleconnection, modulating atmospheric circulation in the North Atlantic, and weakening convection and even the AMOC. This counterintuitive evolution implies a potential destabilizing effect of Antarctic meltwater, and thus highlights the importance of the atmospheric dynamics in the interaction between the two poles.