Freshwater from Antarctica mitigates the risk of an AMOC slowdown

Numerical models have repeatedly shown that accelerating ice melt from Greenland can cause a slowdown in AMOC, with profound effects on Northern Hemisphere temperatures and precipitation patterns ^1–3 . The impacts of Antarctic meltwater on AMOC and climate are less well documented, especially when considered in tandem with freshwater forcing from Greenland. Here we show that increased Antarctic ice sheet (AIS) meltwater can mitigate an AMOC slowdown caused by meltwater from the Greenland Ice Sheet (GIS). In our model, a GIS freshwater discharge of 3000 Gt/yr (~ 0.1 Sv; Sv = 10 ⁶ m ³ /s) is sufficient to weaken the AMOC by up to 10 Sv. However, only a slightly higher discharge of 5000 Gt/yr (0.16 Sv) from the AIS entirely avoids this GIS meltwater-induced AMOC slowdown. These effects are driven by interhemispheric processes linked to the Bipolar Seesaw and operate on decadal timescales. Our results show that despite accelerating ice sheet melt contributing to global sea level rise, a faster rate of ice loss from Antarctica could prevent a future AMOC slowdown triggered by increased meltwater from Greenland.