Abstract
The effect of the North Atlantic Ocean on the Greenland Ice Sheet through submarine melting of Greenland's tidewater glacier calving fronts is thought to be a key driver of widespread glacier retreat, dynamic mass loss and sea level contribution from the ice sheet. Despite its critical importance, problems of process complexity and scale hinder efforts to represent the influence of submarine melting in ice-sheet-scale models. Here we propose parameterizing tidewater glacier terminus position as a simple linear function of submarine melting, with submarine melting in turn estimated as a function of subglacial discharge and ocean temperature. The relationship is tested, calibrated and validated using datasets of terminus position, subglacial discharge and ocean temperature covering the full ice sheet and surrounding ocean from the period 1960-2018. We demonstrate a statistically significant link between multi-decadal tidewater glacier terminus position change and submarine melting and show that the proposed parameterization has predictive power when considering a population of glaciers. An illustrative 21st century projection is considered, suggesting that tidewater glaciers in Greenland will undergo little further retreat in a low-emission RCP2.6 scenario. In contrast, a high-emission RCP8.5 scenario results in a median retreat of 4.2 km, with a quarter of tidewater glaciers experiencing retreat exceeding 10 km. Our study provides a long-term and ice-sheet-wide assessment of the sensitivity of tidewater glaciers to submarine melting and proposes a practical and empirically validated means of incorporating ocean forcing into models of the Greenland ice sheet.
| Original language | English |
|---|---|
| Pages (from-to) | 2489-2509 |
| Number of pages | 21 |
| Journal | Cryosphere |
| Volume | 13 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 26 Sept 2019 |
Funding
1Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA 2Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA 3Atmospheric and Environmental Research, Inc., Lexington, MA, USA 4Utrecht University, Institute for Marine and Atmospheric Research, Utrecht, the Netherlands 5Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium 6Laboratory of Climatology, Department of Geography, University of Liège, Liège, Belgium Acknowledgements. Donald Slater, Fiamma Straneo and Jamie Holte were supported by NSF grants 1916566 and 1756272 and by NASA grant NNX17AI03G. Denis Felikson acknowledges financial support from the NASA Postdoctoral Program. Chris Little acknowledges financial support from NSF grant 1513396. Heiko Goelzer has received funding from the program 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. Computational resources for performing MAR future projections have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S.–FNRS) under grant no. 2.5020.11 and the Tier-1 supercomputer (Zenobe) of the Fédération Wallonie Bruxelles infrastructure funded by the Walloon Region under the grant agreement no. 1117545. We thank Camilla Andresen, Nadine Steiger, James Lea, Konstanze Haub-ner, Ginny Catania, Tom Cowton, Charlie Bunce and Rachel Carr for providing terminus position datasets. Thanks to Brice Noël for RACMO2.3p2 output, to Ellyn Enderlin and Michaela King for ice flux datasets, and to Jeremie Mouginot for sharing ice sheet basin delineations. All members of the ISMIP6 collaboration are thanked for discussions and feedback, with particular thanks to Sophie Now-icki, Mathieu Morlighem, Hélène Seroussi, Alice Barthel and Tim Bartholomaus. tional Aeronautics and Space Administration, Goddard Space Flight Center (postdoctoral program grant), the National Science Foundation, Office of Polar Programs (grant no. 1513396), the Netherlands Earth System Science Centre (grant no. 024.002.001), the Fonds De La Recherche Scientifique – FNRS (grant no. 2.5020.11), the Fédération Wallonie-Bruxelles (grant no. 1117545), the Na- tional Science Foundation, Division of Polar Programs (grant no. 1916566), the National Science Foundation, Office of Polar Programs (grant no. 1756272) and the National Aeronautics and Space Administration (grant no. NNX17AI03G).