Antarctic-wide subglacial hydrology modelling explores controls on ice velocity and ice shelf melt

Global sea levels are rising due, in large part, to the melting of ice sheets and glaciers as a direct result of climate change. Current ice flow models leave out critical components that impact the temporal and spatial dynamics of ice sheets, which results in a significant degree of uncertainty in current sea level rise predictions. One such component is subglacial hydrology, which describes the volume and movement of meltwater underneath glaciers. The presence of liquid water beneath glaciers can increase the glacier’s velocity and the rate of ice shelf melt, both of which can destabilize glaciers and lead to enhanced sea level rise. Here, we present subglacial hydrology model results of the full Antarctic Ice Sheet derived using the Glacier Drainage System (GlaDS) model. We examine water pressures of the distributed drainage system, the size and distribution of the channelized system, and freshwater discharge across grounding lines of the major drainage basins in the steady state subglacial hydrologic system under present day conditions. We compare our modeled channelised grounding line discharge to satellite-derived sub-ice shelf melt rates. Additionally, we compare our water pressure results to those computed using a Shreve hydrology model, which assumes effective pressure to be negligible and computes hydraulic potential using gradients in ice geometry alone. Recent coupling between GlaDS and the Ice-sheet and Sea-level System Model (ISSM) allows for the inclusion of the subglacial hydrologic system in models of ice dynamics. We use the water pressure from our steady state subglacial hydrology results to parameterize an ice flow model and calculate surface velocity. Results are compared to satellite observations of ice velocity and to modeled ice velocities computed without the use of a full subglacial hydrology model.