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Abstract

Determining the multidecadal evolution of ice sheets and the associated sea-level change informs major decisions for coastal hazard mitigation and societal development at the global scale. Such systems involve physical processes occurring within and between ice sheets, terrestrial water, oceans, and the solid Earth. Important feedback loops have been identified in marine-terminating ice sheets between thickness change near the grounding line and the bedrock response. We present a new framework for the Ice Sheet and Sea-level system Model that aims at coupling ice dynamics, hydrology, sea level, and solid-earth deformation. This framework features dynamic interactions between processes with support for multiscale resolution. For example, we are able to capture grounding line dynamics in West Antarctica at a kilometric and biweekly resolution, while global sea level is simultaneously computed on yearly timescales. This is achieved by combining spatial partitioning of physical processes, anisotropic meshing, subelemental geometry tracking, and an asynchronous mass transport approach. Our solid-Earth model is based on high-degree (~10⁴) love numbers and is able to account for viscoelastic response in the lithosphere and mantle to surface loading and rotational feedback. Rheology models supported include the Hookean, Maxwell, Burgers, and Extended Burgers models. Our framework is fully parallelized and optimized to support ensemble modeling for uncertainty quantification purposes. Intended applications include the modeling of ice sheet retreat, sea-level projections, high-resolution coastline migration, Glacial Isostatic Adjustment, and hydrology fingerprints. These will affect the interpretation of numerous geodetic datasets, such as GRACE-FO, GPS, NISAR, ICESat-2, and SWOT. © 2023 California Institute of Technology. Government sponsorship acknowledged.