Steady contribution of northern AMOC source regions under global warming in a high-resolution climate model

<jats:p>Under global warming, the Atlantic Meridional Overturning Circulation (AMOC) is projected to weaken while the Nordic Seas overturning is projected to strengthen. However, it remains unclear whether the increasing Nordic overturning could stabilize the subpolar AMOC. Here, applying AMOC source region diagnostics in density coordinates to high-resolution climate model simulations, we quantify the contributions of the Nordic Seas and the Arctic Ocean to the AMOC under different levels of global warming. The Nordic Seas contribution remains steady until 2100 in a middle-of-the-road scenario but declines under stronger global warming. However, this decline is counterbalanced by an increasing contribution from the Arctic Ocean. We attribute the steady contribution of the northern source regions to northward-shifting persistent surface-forced water mass transformation. However, we find that they have a limited effect on changes in AMOC stability and cannot compensate for the AMOC weakening due to decreasing dense-water formation in the subpolar North Atlantic.</jats:p>