Subglacial lakes and their changing role in a warming climate

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 subglacial lakes (773 total): 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. We use this inventory to evaluate subglacial lake environments, dynamics, and their wider impact on ice flow and sediment transport. Lake behaviour is conditioned by their unique subglacial setting and the hydrologic, dynamic and mass balance regime of the overlying ice mass. We predict that in regions where climate warming causes ice-surface steepening there will be fewer and smaller lakes, but increased activity with higher discharge drainages of shorter duration. 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.