A 3-D coupled ice sheet - sea level model applied to Antarctica through the last 40 ky

We present results from a three-dimensional ice sheet-shelf model of Antarctica, coupled to a gravitationally self-consistent global sea-level model that incorporates (Maxwell) viscoelastic deformation of the solid Earth. The coupled model captures complex post-glacial changes in sea level associated with the gravitational, deformational and rotational effects of the evolving surface mass (ice plus ocean) load over the global ocean, including at the grounding lines of marine-based ice. The simulations are initiated at 40 ka and we focus on ice distributions and sea levels from the Last Glacial Maximum to present. Our results extend and confirm the key conclusions of earlier work using a simplified, 1-D ice-sheet model, by demonstrating that the sea-level coupling has a significant stabilizing influence on marine ice-sheet grounding lines. The feedback of sea-level changes into the ice-sheet model acts to slow down the retreat and advance of the grounding line relative to simulations in which the full coupling is not incorporated. Differences in ice thickness between these simulations can reach ~1 km close to the grounding line. Finally, we perform preliminary comparisons of our results to relative sea level (RSL) histories and GPS-derived present-day uplift rates at sites near the margins of Antarctica. We find that the coupling improves fits to uplift rates in several regions, and that the RSL predictions of the coupled model yield a fit to the observations that is comparable to recent, uncoupled simulations in which the underlying Earth model was varied to obtain a best-fit to the RSL histories.