The evolution of future Antarctic surface melt using PISM-dEBM-simple
Date:
Poster presentation at the 36th Forum for Research into Ice Shelf Processes (FRISP 2023) in Stalheim, Norway.
Abstract
It is virtually certain that Antarctica’s contribution to sea-level rise will increase with future warming. Although mass losses from the ice sheet are currently dominated by ice-shelf basal melting driven by the ocean, surface melting will gain importance under progressing global warming. Meltwater at the ice surface has crucial implications for the ice sheet’s stability as it increases the risk of hydrofracturing and ice-shelf collapse, that could cause enhanced glacier outflow into the ocean. At the same time, self-reinforcing feedbacks between the atmosphere and the ice elevation and albedo may increase the ice sheet’s sensitivity to warming and accelerate mass losses. As yet, however, most ice-sheet models that run on centennial to millennial time scales do not account for surface melt resulting from changes in albedo and thus neglect a strong positive feedback. We here use the novel surface melt module dEBM-simple coupled to the Parallel Ice Sheet Model (PISM) to explore the effects of 21st-century atmospheric warming on Antarctic surface melt and long-term ice dynamics. As an enhancement compared to the widely used positive degree-day (PDD) scheme, dEBM-simple includes an implicit diurnal energy cycle and computes melt not only from temperature, but also accounts for the influence of solar radiation and changes in albedo, thereby accounting for the melt–albedo feedback. Our findings reveal a substantial speed-up in ice flow associated with large-scale elevation reductions in sensitive ice-sheet regions, underscoring the critical role of self-reinforcing ice-sheet–atmosphere feedbacks for future mass losses from the Antarctic Ice Sheet on long time scales.