Rate-induced tipping of ice sheets interacting with the visco-elastic solid Earth

The future stability of the Antarctic Ice Sheet is determined by the marine ice sheet instability (MISI), an amplifying feedback, leading to potentially irreversible retreat. Glacial isostatic adjustment (GIA) potentially provides a stabilizing feedback, yet its influence on the timing and nature of ice-sheet tipping dynamics remains poorly constrained. Using an ensemble of idealized simulations in a synthetic Antarctic-type ice-sheet–shelf system, we systematically investigate how interactions between ice dynamics and the visco-elastic solid Earth affect MISI tipping dynamics under increasing basal ice-shelf melt. We find that the critical thresholds for bifurcation tipping strongly depend on the timescale and spatial extent of Earth deformation, increasing substantially (order of magnitude) relative to a fixed-bed (rigid) case.

For half of the ensemble members, rate-induced tipping occurs when melt rates increase sufficiently rapidly, triggering MISI before the threshold for bifurcation tipping is reached and reducing the effective tipping threshold by up to 80%. Bed uplift cannot halt MISI once initiated, due to rapid grounding-line retreat. We further identify grounding-line overshoots and self-sustained oscillations driven solely by internal ice - Earth interactions.

We find similar dynamics in more realistic simulations of the Antarctic Ice Sheet with a coupled ice sheet - solid Earth and sea-level model considering a three-dimensional Earth structure. Our results highlight that both the magnitude and rate of future climate forcing critically influence Antarctic ice-sheet stability.