Paper No. 139-4
Presentation Time: 8:50 AM
RAPID POSTGLACIAL REBOUND AMPLIFIES GLOBAL SEA-LEVEL RISE FOLLOWING WEST ANTARCTIC ICE SHEET COLLAPSE
Studies of peak global mean sea level (GMSL) during the Last Interglacial (LIG; 130-116 ka) commonly cite values ranging from ~2-5 m for the maximum contribution from grounded, marine-based sectors of the West Antarctic Ice Sheet (WAIS). This estimate does not include postglacial rebound and the associated meltwater flux out of marine sectors as they become exposed by retreating ice, a contribution typically considered to be small and slowly accumulating. However, geodetic, seismic and geological evidence indicate that West Antarctica is underlain by low-viscosity shallow mantle, and thus the assumption that the contribution to GMSL from the outflux mechanism is negligible should be revisited. We incorporate both the outflux mechanism and complex 3-D viscoelastic mantle structure in new sea-level predictions and find that the water outflux mechanism contributes ~1 m of additional GMSL change within ~1 kyr of WAIS collapse. This conclusion has important implications for the sea-level budget not only during the LIG, but also during all previous interglacials. Finally, we discuss the importance of including this mechanism in analyses of site-specific sea-level indicators, as well as the inaccuracies that are introduced by the common assumption that the Earth’s viscoelastic structure varies with depth alone.