Antarctic grounding zone and bedrock: the interplay shaping Antarctic sea-level contribution.

Grounding zones have long been recognized as critical for understanding the past, present and future evolution of ice sheets. The ice mass flux through the grounding line contributes to global sea-level rise, and the freshwater flux impacts ocean salinity. This narrow zone-where the grounded ice sheet transitions into a floating shelf-is challenging to observe and model because of the remoteness of ice sheet beds and ice shelf cavities and is thus poorly understood. However, our understanding of grounding zones has changed as we collect new observations, which are revealing a far more complex system than previously thought. These observations serve as the foundation for mathematical and numerical models of ice sheets. Models have progressed from simply representing the grounding line as hydrostatic equilibrium and treating ice flow as a viscous fluid to solving visco-elastic problems, including coupled ice sheet-subglacial hydrological models and complex grounding zones. What all these models, however, have in common is the need to know the shape of the bedrock and basal conditions beneath the grounded ice, making a targeted observational campaign of bedrock in current and future possible grounding zones key to fully understanding the Antarctic ice sheet. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.