TY - JOUR
T1 - Twenty-first century ocean forcing of the Greenland ice sheet for modelling of sea level contribution
AU - Slater, Donald A.
AU - Felikson, Denis
AU - Straneo, Fiamma
AU - Goelzer, Heiko
AU - Little, Christopher M.
AU - Morlighem, Mathieu
AU - Fettweis, Xavier
AU - Nowicki, Sophie
N1 - 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).
PY - 2020/3/16
Y1 - 2020/3/16
N2 - 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 approximately triple by 2100 under RCP8.5. Both implementations have necessarily made use of simplifying assumptions and poorly constrained parameterisations and, as such, further research on submarine melting, calving and fjord-shelf exchange should remain a priority. Nevertheless, the presented framework will allow an ensemble of Greenland ice sheet models to be systematically and consistently forced by the ocean for the first time and should result in a significant improvement in projections of the Greenland ice sheet's contribution to future sea level change.
AB - 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 approximately triple by 2100 under RCP8.5. Both implementations have necessarily made use of simplifying assumptions and poorly constrained parameterisations and, as such, further research on submarine melting, calving and fjord-shelf exchange should remain a priority. Nevertheless, the presented framework will allow an ensemble of Greenland ice sheet models to be systematically and consistently forced by the ocean for the first time and should result in a significant improvement in projections of the Greenland ice sheet's contribution to future sea level change.
U2 - 10.5194/tc-14-985-2020
DO - 10.5194/tc-14-985-2020
M3 - Article
AN - SCOPUS:85082039794
SN - 1994-0416
VL - 14
SP - 985
EP - 1008
JO - Cryosphere
JF - Cryosphere
IS - 3
ER -