A Collapsed AMOC State Raises the Global Warming Threshold at Which the Greenland Ice Sheet Collapses

The Atlantic Meridional Overturning Circulation (AMOC) and the Greenland Ice Sheet (GrIS) are important interacting climate tipping elements. A collapsed AMOC state could lead to a more stable GrIS through Northern Hemisphere cooling, but it might also reduce its stability through reduced snowfall over Greenland, lowering its surface mass balance. The net effect of these competing feedbacks remains understudied. Using the Earth system model CLIMBER-X coupled to the ice sheet model Yelmo, we examined how a collapsed AMOC affects the tipping point of the GrIS. We computed the quasi-equilibria of the GrIS under CO 2 forcing for both an active and a collapsed AMOC state and performed transient experiments to compare the melt rates of the GrIS for both AMOC scenarios. We show that a collapsed AMOC state delays the tipping of the GrIS, raising its tipping point by 160 ppm CO 2 , equivalent to 0.9 ∘ C of global warming.