Rapid Viscoelastic Deformation Slows Marine Ice Sheet Instability at Pine Island Glacier, West Antarctica
A coupled solid-earth and ice sheet model is used to simulate the evolution of West Antarctica’s Pine Island Glacier for a range of potential mantle viscosities. The work uses DOE's BISICLES ice sheet model with adaptive mesh refinement to resolve ice flow down to 500 m resolution, which is essential for accurately simulating realistic grounding line dynamics.
Solid-earth feedbacks, from viscoelastic glacial isostatic adjustment in response to unloading from ice sheet thinning, have the potential to mitigate marine ice sheet grounding line retreat and mass loss due to the marine ice sheet instability. For Pine Island Glacier, West Antarctica, we find that viscoelastic uplift on timescales similar to grounding line migration can be a leading term in strongly mitigating rates of sea-level rise due to the marine ice sheet instability. We examine the feedback between ice sheet dynamics and solid-earth viscoelastic response and its impact on grounding-line (GL) stability and sea-level rise (SLR).
Portions of the West Antarctic Ice Sheet are vulnerable to an instability that could lead to rapid ice sheet collapse, significantly raising sea levels, but the timing and rates of collapse are highly uncertain. In response to such a large‐scale loss of overlying ice, viscoelastically deforming mantle material uplifts the surface, alleviating some drivers of unstable ice sheet retreat. While previous studies have focused on the effects mantle deformation has on continental ice dynamics over centuries to millennia, recent seismic observations suggest that the mantle beneath West Antarctica is hot and weak, potentially affecting local glacial dynamics over timescales as short as decades. To measure the importance of viscoelastic uplift in stabilizing grounding line retreat, we coupled a high‐resolution ice flow model to a viscoelastically deforming mantle. We find that rapid viscoelastic uplift can reduce the total volume of ice lost over 150 years by 30%, or 18 mm of equivalent sea-level rise, making it an essential process to consider when using models to project the future evolution of marine‐based ice retreat.