Coupled grounding line migration/solid-Earth uplift in West Antarctica

We present a new investigation of the complex interactions between global relative sea-level (RSL) changes and local ice-sheet dynamics in Antarctica, with special focus on the grounding line of Thwaites Glacier. There is indeed heightened interest in negative feedbacks caused by solid-Earth effects. For example, Barletta et al, 2018 modeled GPS data, combined with an ice retreat scenario, to strongly argue for an ongoing negative feedback induced by solid earth deformation in West Antarctica. This type of fast deformation is not always incorporated into contemporary sea level projections. Here, we present a state-of-the-art global spherical ice-sheet/RSL simulation that accounts for fast grounding line dynamics and local RSL feedbacks such as self-attraction and loading (SAL) and vertical elastic land motion. In addition, we capture ice/ocean feedbacks along the grounding line using parameterizations calibrated against ice/ocean coupled model runs from Seroussi et al, 2017. These feedback are essential in constraining the evolution of Thwaites Glacier in the next two to three centuries. We compare our results with current estimates of ice flux, surface velocities and solid-Earth uplift. We discuss the implications of our results in terms of stability of the West-Antarctic Ice Sheet area, and how they relate to other modeling studies that envision more aggressive scenarios of ice-sheet collapse.