Rapid postglacial rebound amplifies global sea level rise following West Antarctic Ice Sheet collapse

Geodetic, seismic, and geological evidence indicates that West Antarctica is underlain by low-viscosity shallow mantle. Thus, as marine-based sectors of the West Antarctic Ice Sheet (WAIS) retreated during past interglacials, or will retreat in the future, exposed bedrock will rebound rapidly and flux meltwater out into the open ocean. Previous studies have suggested that this contribution to global mean sea level (GMSL) rise is small and occurs slowly. We challenge this notion using sea level predictions that incorporate both the outflux mechanism and complex three-dimensional viscoelastic mantle structure. In the case of the last interglacial, where the GMSL contribution from WAIS collapse is often cited as similar to 3 to 4 meters, the outflux mechanism contributes similar to 1 meter of additional GMSL change within similar to 1 thousand years of the collapse. Using a projection of future WAIS collapse, we also demonstrate that the outflux can substantially amplify GMSL rise estimates over the next century.

Automated summary

Geodetic, seismic, and geological evidence suggest that West Antarctica possesses a low-viscosity shallow mantle layer. As the Antarctic ice sheet retreats, exposed bedrock will rebound and meltwater will flow into the ocean rapidly. Contrary to previous beliefs, recent research challenges the idea that the contribution of West Antarctica to global mean sea level rise is small and occurs slowly.