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

Abstract

Abstract. We use the Shreve hydraulic potential equation as a simplified approach to investigate potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland ice sheets. We validate the method by demonstrating its ability to recall the locations of > 60 % of the known subglacial lakes beneath the Antarctic Ice Sheet. This is despite uncertainty in the ice-sheet bed elevation and our simplified modelling approach. However, we predict many more lakes than are observed. Hence we suggest that thousands of subglacial lakes remain to be found. Applying our technique to the Greenland Ice Sheet, where very few subglacial lakes have so far been observed, recalls 1607 potential lake locations, covering 1.2 % of the bed. Our results will therefore provide suitable targets for geophysical surveys aimed at identifying lakes beneath Greenland. We also apply the technique to modelled past ice-sheet configurations and find that during deglaciation both ice sheets likely had more subglacial lakes at their beds. These lakes, inherited from past ice-sheet configurations, would not form under current surface conditions, but are able to persist, suggesting a retreating ice-sheet will have many more subglacial lakes than advancing ones. We also investigate subglacial drainage pathways of the present-day and former Greenland and Antarctic ice sheets. Key sectors of the ice sheets, such as the Siple Coast (Antarctica) and NE Greenland Ice Stream system, are suggested to have been susceptible to subglacial drainage switching. We discuss how our results impact our understanding of meltwater drainage, basal lubrication and ice-stream formation.

Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland

“…The presence of at least some localised patches of high abruptness in thawed regions is consistent with the recent discovery of two small subglacial lakes in north-western Greenland of ∼ 8 and ∼ 10 km 2 in extent (Palmer et al, 2013). More generally, however, the relative rarity of high abruptness in thawed regions is in agreement with hydrological potential analysis (Livingstone et al, 2013), which predicts that deep subglacial lakes are both rare and small in the north-west of the GrIS. Instead, channelised drainage networks -such as the system recently identified beneath Humboldt glacier (Livingstone et al, 2017) -are likely to be common in thawed regions (and are consistent with the generally diffuse scattering signature that we observe).…”

Response of the large-scale subglacial drainage system of Northeast Greenland to surface elevation changes

“…This is in agreement with previous studies, which have also found a potential for changes in drainage pattern (Livingstone et al, 2013;Christianson et al, 2014).…”

“…5b) the water routeways can be seen to pool together in the southeastern part of the drainage basin, indicating the possibility of subglacial lakes. Their positions correspond largely to areas identified by Livingstone et al (2013) as potential lake locations. However, the areas likely to contain subglacial lakes in our study coincide not only with areas where the bed slope is equally or more important than the surface slope, but also with areas where the error in bed rock topography is upwards of 300 m (Fig.…”

Active subglacial lakes and channelized water flow beneath the Kamb Ice Stream

“…Streamlines derived from the hydraulic potential gradient map pass though the lakes. The lakes are also located on a "potential subglacial lake" area, identified from previous analysis of continent-wide subglacial hydraulic potential (Livingstone et al, 2013). Figure 4 shows the elevation and volume changes of three SGLs, representing sequential filling events in 2013.…”