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 due 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 kilometers or more. Advances in
modeling capabilities now allow for the application of dynamic coupling
between subglacial hydrology and ice dynamics in models of Antarctica.
While a bed resolution of ~1 km is recommended for modeling 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.