WAIS Collapse Not Prevented by Earth Surface Rebound Under High Emissions

Journal of Geophysical Research: Earth Surface, June 18

When an ice sheet loses mass, the pressure it exerts on the underlying Earth surface decreases, leading to a gradual bedrock uplift and an elevation gain that could potentially help stabilize the Antarctic ice sheet, slowing loss and related sea-level rise. In particular, the fast uplift rates due to the weak mantle under the West Antarctic Ice Sheet (WAIS) have been invoked as a potential mechanism to slow future ice loss over that region. However, a new model of uplift tested against observations shows that especially under high emissions, the climate forcing overrides this negative feedback, leading to a rapid (< 1000 years) and irreversible collapse of the WAIS. This loss is slowed, though not entirely overridden at lower emissions scenarios, especially those consistent with 1.5°C of warming; with overshoot scenarios (above 2°C) showing more rapid loss. Conversely, in East Antarctica the thicker mantle prevents much rebound, and therefore this process has little impact on rates of ice loss. Most models currently used could therefore be overestimating the stabilizing effect of the Earth surface rebound effect, not only from the WAIS; but also from East Antarctica. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JF006003