Modelling subglacial responses to future moulin inputs in the Amundsen Sea Embayment

At present, there is minimal surface meltwater over Antarctica and Antarctic subglacial drainage systems are isolated from supraglacial water, differentiating them from the surface meltwater-fed hydrological networks of Greenland. However, projected increases in surface melt across grounded regions of the Antarctic Ice Sheet raise the possibility that surface-to-bed hydrological connections may begin to form via moulins, features known in Greenland to drive seasonal ice velocity variability by modulating subglacial water pressure. In Antarctica, additional seasonal water fluxes into the subglacial drainage system could amplify the effects that subglacial channels have on ice dynamics and sub-ice shelf melt rates, which could, in turn, impact grounding line positions and stability and alter the rate of sea level rise. Here, we investigate the response of the Amundsen Sea Embayment (ASE), where rapid, potentially irreversible changes are underway, to new subglacial meltwater forcing from moulin inputs. To accomplish this, we develop a moulin prediction algorithm that uses surface melt projections at 2100 and 2300 from UKESM and strain rates derived from the Ice Sheet and Sea Level Systems Model (ISSM). We then use these moulin locations and discharges as input to the Glacier Drainage System (GlaDS) subglacial hydrology model. We simulate five consecutive melt seasons followed by an extended recovery period to evaluate whether episodic meltwater inputs leave a long-term imprint on the ASE's drainage system. We provide a mosaic of possible trajectories for ASE's subglacial drainage system by varying GlaDS internal parameters and the strain-rate threshold, complemented by an additional set of experiments that use a randomly generated moulin distribution. This approach allows us to better gauge the sensitivity and responsiveness of the ASE's drainage systems to perturbations from surface meltwater inputs, with knock-on effects for glacier stability. Ultimately, our work provides an improved understanding of how surface-bed hydrological pathways may influence the future evolution of the Antarctic Ice Sheet in a warming climate.