The Greenland ice sheet is one of the largest contributors to global mean sea-level rise today and is expected to continue to lose mass as the Arctic continues to warm. The two predominant mass loss mechanisms are increased surface meltwater run-off and mass loss associated with the retreat of marine-terminating outlet glaciers. In this paper we use a large ensemble of Greenland ice sheet models forced by output from a representative subset of the Coupled Model Intercomparison Project (CMIP5) global climate models to project ice sheet changes and sea-level rise contributions over the 21st century. The simulations are part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6).We estimate the sea-level contribution together with uncertainties due to future climate forcing, ice sheet model formulations and ocean forcing for the two greenhouse gas concentration scenarios RCP8.5 and RCP2.6. The results indicate that the Greenland ice sheet will continue to lose mass in both scenarios until 2100, with contributions of 90-50 and 32-17mm to sea-level rise for RCP8.5 and RCP2.6, respectively. The largest mass loss is expected from the south-west of Greenland, which is governed by surface mass balance changes, continuing what is already observed today. Because the contributions are calculated against an unforced control experiment, these numbers do not include any committed mass loss, i.e. mass loss that would occur over the coming century if the climate forcing remained constant. Under RCP8.5 forcing, ice sheet model uncertainty explains an ensemble spread of 40 mm, while climate model uncertainty and ocean forcing uncertainty account for a spread of 36 and 19 mm, respectively. Apart from those formally derived uncertainty ranges, the largest gap in our knowledge is about the physical understanding and implementation of the calving process, i.e. the interaction of the ice sheet with the ocean.
Bibliographical noteFunding Information:
Financial support. Heiko Goelzer has received funding from the programme of the Netherlands Earth System Science Centre (NESSC), financially supported by the Dutch Ministry of Education, Culture and Science (OCW), under grant no. 024.002.001. For NCAR-CISM this material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under cooperative agreement no. 1852977. Computing and data storage resources, including the Cheyenne supercomputer (https://doi.org/10.5065/D6RX99HX), were provided by the Computational and Information Systems Laboratory (CISL) at NCAR. Alice Barthel was supported by the US Department of Energy (DOE) Office of Science Regional and Global Model Analysis (RGMA) component of the Earth and Environmental System Modeling (EESM) programme (HiLAT-RASM project) and the DOE Office of Science (Biological and Environmental Research) Early Career Research programme. Philippe Huybrechts and Sébastien Le clec’h acknowledge support from the iceMOD project funded by the Research Foundation – Flanders (FWO-Vlaanderen). Ralf Greve and Chris Chambers were supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant no. JP16H02224). Ralf Greve was supported by JSPS KAK-ENHI (grant no. JP17H06104) and by the Arctic Challenge for Sustainability (ArCS) project of the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) under programme grant no. JPMXD1300000000. Reinhard Calov was funded by the Bundesministerium für Bildung und Forschung (BMBF; grants PalMod-1.1 and PalMod-1.3). Support for Nicholas Golledge and Daniel Lowry was provided by the New Zealand Ministry of Business Innovation and Employment (contract RTVU1705). Martin Rückamp received support from the Helmholtz Climate Initiative REKLIM (Regional Climate Change). The AWI-ISSM simulations were run on the DKRZ HPC system Mistral under grant ab1073. Jonathan Gregory and Robin S. Smith were supported by the National Centre for Atmospheric Science, funded by the UK National Environment Research Council. Work was performed by Nicole Schlegel and Helene Seroussi at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Funding was provided by grants from the Jet Propulsion Laboratory Research Technology and Development programme. Sophie Nowicki, Erika Simon, Isabel Nias, Helene Seroussi and Nicole Schlegel were supported by the NASA programmes Cryosphere Sciences; Sea Level Change Team; and Modeling, Analysis, and Prediction. Mathieu Morlighem and Joshua Cuzzone were funded by the National Science Foundation’s ARCSS programme (grant no. 1504230). Young-min Choi was supported by the NASA Earth and Space Science Fellowship programme grant (grant no. 80NSSC17K0409). Denis Felikson was supported by an appointment to the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASA. Fiammetta Straneo and Donald A. Slater received support from the NSF.
© Author(s) 2020.
FingerprintDive into the research topics of 'The future sea-level contribution of the Greenland ice sheet: A multi-model ensemble study of ISMIP6'. Together they form a unique fingerprint.
Sadaf R Alam (Manager), Steven A Chapman (Manager), Polly E Eccleston (Other), Simon H Atack (Other) & D A G Williams (Manager)