Potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets

摘要

We use the Shreve hydraulic potential equation as a simplified approach toinvestigate potential subglacial lake locations and meltwater drainagepathways beneath the Antarctic and Greenland ice sheets. We validate themethod by demonstrating its ability to recall the locations of >60% ofthe known subglacial lakes beneath the Antarctic Ice Sheet. This is despiteuncertainty in the ice-sheet bed elevation and our simplified modellingapproach. However, we predict many more lakes than are observed. Hence wesuggest that thousands of subglacial lakes remain to be found. Applying ourtechnique to the Greenland Ice Sheet, where very few subglacial lakes have sofar been observed, recalls 1607 potential lake locations, covering 1.2%of the bed. Our results will therefore provide suitable targets forgeophysical surveys aimed at identifying lakes beneath Greenland. We alsoapply the technique to modelled past ice-sheet configurations and find thatduring deglaciation both ice sheets likely had more subglacial lakes at theirbeds. These lakes, inherited from past ice-sheet configurations, would notform under current surface conditions, but are able to persist, suggesting aretreating ice-sheet will have many more subglacial lakes than advancingones. We also investigate subglacial drainage pathways of the present-day andformer Greenland and Antarctic ice sheets. Key sectors of the ice sheets,such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, aresuggested to have been susceptible to subglacial drainage switching. Wediscuss how our results impact our understanding of meltwater drainage, basallubrication and ice-stream formation.