The Impact of Variable Ocean Temperatures on Totten Glacier Stability and Discharge
Felicity S. McCormack, Jason L. Roberts, David E. Gwyther, Mathieu Morlighem, Tyler Pelle, Benjamin K. Galton‐Fenzi
Abstract
Abstract A major uncertainty in Antarctica's contribution to future sea‐level rise is the ice sheet response timescales to ocean warming. Totten Glacier drains a region containing 3.9 m global sea level equivalent and has been losing mass over recent decades. We use an ice sheet model coupled to an ice‐shelf cavity combined ocean box and plume model to investigate Totten's response to variable ocean forcing. Totten's grounding line is stable for a limited range of ocean temperatures near current observations (i.e., −0.95°C to −0.75°C), with topography influencing the discharge periodicity. For increases of ≥0.2°C in temperatures beyond this range, grounding line retreat occurs. Variable ocean forcing can reduce retreat relative to constant forcing, and different variability amplitudes can cause centennial‐scale delays in retreat through interactions with topography. Our results highlight the need for long‐term ocean state observations and to include forcing variability in ice sheet model simulations of future change.