Twenty-first century ocean forcing of the Greenland ice sheet for modelling of sea level contribution

• Published in: The Cryosphere
• Main Authors: Slater, Donald A., Felikson, Denis, Straneo, Fiamma, Goelzer, Heiko, Little, Christopher M., Morlighem, Mathieu, Fettweis, Xavier, Nowicki, Sophie
• Other Authors: University of St Andrews. School of Geography & Sustainable Development
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: GC Oceanography; GE Environmental Sciences; Water Science and Technology; Earth-Surface Processes; DAS; SDG 13 - Climate Action; GC; GE; Greenland; glacier; Ice Sheet; National Science Foundation Office of Polar Programs
• Online Access: http://hdl.handle.net/10023/19751; https://doi.org/10.5194/tc-14-985-2020

This research has been supported by the National Science Foundation, Office of Polar Programs (grant no. 1916566), the National Science Foundation, Division of Ocean Sciences (grant no. 1756272), the National Aeronautics and Space Administration (grant no. NNX17AI03G), the National Science Foundation, Office of Polar Programs (grant nos. 1513396 and 1504230), the Netherlands Earth System Science Centre (grant no. 024.002.001), the Fonds De La Recherche Scientifique – FNRS (grant no. 2.5020.11), and the FédérationWallonie-Bruxelles (grant no. 1117545). Changes in ocean temperature and salinity are expected to be an important determinant of the Greenland ice sheet's future sea level contribution. Yet, simulating the impact of these changes in continental-scale ice sheet models remains challenging due to the small scale of key physics, such as fjord circulation and plume dynamics, and poor understanding of critical processes, such as calving and submarine melting. Here we present the ocean forcing strategy for Greenland ice sheet models taking part in the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), the primary community effort to provide 21st century sea level projections for the Intergovernmental Panel on Climate Change Sixth Assessment Report. Beginning from global atmosphere-ocean general circulation models, we describe two complementary approaches to provide ocean boundary conditions for Greenland ice sheet models, termed the "retreat" and "submarine melt" implementations. The retreat implementation parameterises glacier retreat as a function of projected subglacial discharge and ocean thermal forcing, is designed to be implementable by all ice sheet models and results in retreat of around 1 and 15 km by 2100 in RCP2.6 and 8.5 scenarios, respectively. The submarine melt implementation provides estimated submarine melting only, leaving the ice sheet model to solve for the resulting calving and glacier retreat and suggests submarine melt rates will change little under RCP2.6 but will ...