From grounding lines to coastlines: an integrated approach to barystatic sea-level projections.

PI: Eric Larour

Co-Is/Collaborators:

Surendra Adhikari, Lambert Caron, Chunli Dai, Alex Gardner, Ian Howat, Erik Ivins, Dimitris Menemenlis, Justin Quinn, Nicole-Jeanne Schlegel, Helene Seroussi, Sophie Nowicki, Thomas Frederikse.

Background

We propose to leverage the Ice-Sheet and Sea-Level System Model (ISSM) capabilities to model relative sea-level (RSL), GIA (Glacial-Isostastic Adjustment) and ice-sheet dynamics, as well as the MIT General Circulation model (MITgcm) and the Estimating the circulation and Climate of the Ocean project (ECCO) to model ocean-circulation, dynamic sea-level and steric-expansion, towards projecting RSL for the next 100 years. The projections will fully account for all sources of uncertainty and include full coupling to all elements of the climate when possible or computationally feasible.

Expected Significance

Through the proposed work we will establish an architecture for systematically building, and then expanding, NASA sea-level projection capabilities. Unique to our effort is that these projection capabilities will be rooted in the physical processes that are associated with ice sheet, land cryosphere and ocean circulation change. The architecture is being specifically designed to maximize the participation of any of the individual research efforts within the peer view of the NSLC-T that can contribute to the generation of a PDF for components of global- and site-specific sea level change. The significance of this architecture is that it can absorb new models and new data inputs, and yet it can also rely on the same basic flow of information in the construction of updated PDFs.

Objectives:

1. Gain understanding of how current probabilistic regional sea-level projections can be improved by the use of time-correlated forward ice-sheet and GIA model projections.
2. Understand how ocean circulation around the Antarctic Ice Sheet (AIS) impacts grounding line (GL) retreat of ice streams and how this translates into specific patterns of predicted coastline migration around the world.
3. Understand the impact of a generalized representation of mantle creep (that allow for soft-mantle rheologies) on both the evolution of GL position in the West Antarctic Ice Sheet (WAIS) and coastal migration around the world.
4. Quantify the impact of the improvements in GL dynamics and understand the associated consequences for sea-level projections and coastline evolution around the world.

Deliverables (e.g. Datasets, Tools)

A sea-level projection system built into ISSM. 100-year probabilistic sea-level projections at high temporal and spatial resolution, taking into account full temporal coherence of forcings, and accounting for all sources of uncertainty. Visualization tools for projections included into the N- SLCT portal.