Impacts of bed topography resolution on sea-level rise projections from coupled subglacial hydrology and ice dynamics for Thwaites Glacier, Antarctica.

Ice-sheet models require explicit knowledge of the underlying bed. However, much remains unknown regarding the subglacial environment owing to difficulties associated with measuring it. Extensive radar surveys have been conducted across Antarctica, but the requirement of full-coverage bed topography for models necessitates interpolation over gaps between existing observations, which often span kilometres or more. Advances in modelling capabilities now allow for the application of dynamic coupling between subglacial hydrology and ice dynamics in models of Antarctica. While a bed resolution of approximately 1 km is recommended for modelling Antarctic ice dynamics, it has been suggested that finer spatial resolutions are necessary to resolve subglacial water flow. We use a coupled model configuration to generate projections of glacier evolution, including the subglacial hydrologic system, for Thwaites Glacier, West Antarctica, initiated with several different bed topographies. We find that the specific bed topography has a first-order control on accumulated mass loss, but that final sea-level rise does not scale with bed resolution. We also find that coupling between subglacial hydrology and ice dynamics results in faster mass loss. Our results underscore the importance of continued high-resolution topography mapping and suggest that current projections may underestimate uncertainty linked to unresolved bed features. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.