Subglacial lakes and their changing role in a warming climate

Abstract

Subglacial lakes store ancient climate records, provide habitats for life, and modulate ice flow, basal hydrology, biogeochemical fluxes and geomorphic activity. In this Review, we construct the first global inventory of 773 subglacial lakes, including 675 from Antarctica (59 newly identified in this study), 64 from Greenland, 2 beneath Devon Ice Cap, 6 beneath Iceland's ice caps, and 26 from valley glaciers. The inventory is used to evaluate subglacial lake environments, dynamics, and their wider impact on ice flow and sediment transport. We suggest their behaviour is conditioned by the subglacial setting and the hydrologic, dynamic and mass balance regime of the ice mass above. Using space-time substitution, we predict fewer and smaller lakes but increased activity with higher discharge drainages of shorter duration where climate warming causes ice-surface steepening. Coupling to surface melt and rainfall inputs will modulate fill-drain cycles and seasonally enhance oxic processes. Higher discharges cause large, transient ice-flow accelerations, but might result in overall net slowdown due to development of efficient subglacial drainage. Future subglacial lake research requires new drilling technologies, and the integration of geophysics, satellite monitoring and numerical modelling, which will provide new insight into their wider role in a changing Earth system.

Filling and drainage of a subglacial lake beneath the Flade Isblink ice cap, northeast Greenland

“…At total of 64 subglacial lakes have been identified in Greenland from airborne radio-echo sounding Livingstone et al, 2022). Most of them are stable, showing little or no evidence of volume change or input from the surface, and are located between the equilibrium line altitude (ELA) and the relatively flat, frozen-bed ice sheet interior.…”

“…Most of them are stable, showing little or no evidence of volume change or input from the surface, and are located between the equilibrium line altitude (ELA) and the relatively flat, frozen-bed ice sheet interior. Only a few hydrologically active lakes that are recharged by surface meltwater have been identified from ice surface elevation change measurements Howat et al, 2015;Livingstone et al, 2019Livingstone et al, , 2022Palmer et al, 2015;Willis et al, 2015). Compared to the widely distributed stable subglacial lakes, the active subglacial lakes are affected more directly by surface meltwater, and their drainage may significantly influence glacier flow dynamics (Davison et al, 2020;Livingstone et al, 2019).…”

Drainage and refill of an Antarctic Peninsula subglacial lake reveals an active subglacial hydrological network

“…descriptions of 'water-filled cavities that drain rapidly beneath valley glaciers' (Fig. 7c in Livingstone et al, 2022). However, circular ice depressions, referred to as 210 'ice cauldrons' (or 'ice caldera') have also been recognised in areas of volcanic or geothermal activity, for example in Iceland (e.g.…”

“…Changes in glacial and subglacial hydrology can result in significant impacts on glacier and ice sheet dynamics including accelerating ice flow (Bartholomew et al, 2012). Active subglacial hydrological networks have been 20 revealed from changes in ice surface elevation detected by airborne radio-echo sounding and satellite altimetry (Livingstone et al, 2022), and overland seismic surveys have been used to detect water column, sediment properties and overlying ice sheet behaviour in subglacial lakes (Smith et al, 2018). Much of this work has been carried out on large subglacial lakes under the East and West Antarctic Ice Sheets, while small lakes under the valley glaciers of the Antarctic Peninsula Ice Sheet have received comparatively little attention (cf.…”

“…the study of 25 Alaskan alpine subglacial lakes by Capps et al, 2010). In a recent global inventory of subglacial lakes, only one is included on the Antarctic Peninsula (Livingstone et al, 2022) beneath Crane Glacier in northeast Graham Land (Scambos et al, 2011), and another has previously been described and directly sampled on Alexander…”