E4.9 Antarctic Sea Level Rise

Abstract

We present results from recent simulations aimed at estimating an upper bound on the potential sea-level rise resulting from Antarctic ice sheet dynamics. In particular, we target the “marine ice sheet instability”, a dynamic feedback whereby an initial perturbation causing retreat of the ice sheet grounding line – the point at which portions of the ice sheet become thin enough to go afloat from buoyancy – is amplified, leading to further retreat, further increases in ice flux to the oceans, and further increases in Antarctica’s contribution to global sea-level rise. Importantly, an accurate representation of these critical ice sheet dynamics requires spatial resolution of order 1 km in the vicinity of ice sheet grounding lines. We achieve these resolutions for computationally efficient, whole-ice-sheet, multi-century simulations of Antarctic ice sheet evolution using adaptive and unstructured meshes within the U.S. Department of Energy’s BISICLES (Cornford et al., 2013) and MALI (Hoffman et al., 2018) ice sheet models. In this presentation, we present results from these models that aim to better constrain the potential upper bound on sea-level rise from Antarctica under extreme perturbations (e.g., due to the complete loss of floating ice shelves). The use of multiple models for identical perturbation experiments allows for an estimate of how structural error impacts sea level projections from ice sheet models.