Articles | Volume 19, issue 8
https://doi.org/10.5194/tc-19-3253-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-19-3253-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Brief communication
| 
25 Aug 2025
Brief communication |
| 25 Aug 2025
| 25 Aug 2025
Brief communication: Representation of heat conduction into ice in marine ice shelf melt modelling
Jonathan Wiskandt
CORRESPONDING AUTHOR
Department of Meteorology, Stockholm University, Stockholm, Sweden
Bolin Centre for Climate Research, Stockholm, Sweden
Nicolas C. Jourdain
Univ. Grenoble Alpes/CNRS/IRD/G-INP/INRAE, IGE, Grenoble, France
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Understanding ice–ocean interactions under floating ice tongues in Greenland and Antarctica is a major challenge in climate modelling and a source of uncertainty in future sea level projections. We use a high-resolution ocean model to investigate basal melting and melt-driven circulation under the floating tongue of Ryder Glacier, northwestern Greenland. We study the response to oceanic and atmospheric warming. Our results are universal and relevant for the development of climate models.
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Since numerical computing is expensive, climate models must decide between having a high spatial resolution or running for long time periods. Here, we develop a simple neural network to emulate small-scale processes occurring beneath Antarctic ice shelves, which allows sub-shelf melt and ice–ocean interactions to be included in global ocean models which can run for multiple centuries. This neural network will help us to understand how ocean circulation may change in the future.
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Antarctic icebergs release large amounts of freshwater, but models often add it entirely at the ocean surface. Using simulations with drifting icebergs, we assessed whether releasing meltwater at depth alters the Southern Ocean's response. Most meltwater remained in the surface mixed layer, and deeper release caused only weak, local changes in the ocean, sea ice and ice shelf melting. Hence, surface release remains a reasonable approach for large-scale studies, though depth matters regionally.
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How the Antarctic ice sheet responds to rapid ocean warming remains uncertain. To explore this, we used a coupled ocean–ice sheet model. We compared simulations under present-day conditions with simulations under strong future warming for 50 years, then returned to today’s climate. The ocean warmed quickly but recovered within decades. In contrast, several ice streams continued to retreat for centuries. This shows that even brief warming could cause lasting ice loss and sea-level rise.
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We studied how the Antarctic ice sheet surface mass balance may change by 2100 using three high-resolution climate models forced by the same future climate scenario. While the models agree for present-day conditions, they project very different futures, especially over floating ice shelves. These differences mainly come from how melting, refreezing, and temperature are represented. Our results show that future sea level projections strongly depend on how well models simulate today’s climate.
Yavor Kostov, Paul R. Holland, Kelly A. Hogan, James A. Smith, Nicolas C. Jourdain, Pierre Mathiot, Anna Olivé Abelló, Andrew H. Fleming, and Andrew J. S. Meijers
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Icebergs ground when they reach shallow topography such as Bear Ridge in the Amundsen Sea. Grounded icebergs can block the transport of sea-ice and create areas of higher and lower sea-ice concentration. We introduce a physically and observationally motivated representation of grounding in an ocean model. In addition, we improve the way simulated icebergs respond to winds, ocean currents, and density differences in sea water. We analyse the forces acting on freely floating and grounded icebergs.
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Johanna Beckmann, Ronja Reese, Felicity S. McCormack, Sue Cook, Lawrence Bird, Dawid Gwyther, Daniel Richards, Matthias Scheiter, Yu Wang, Hélène Seroussi, Ayako Abe‐Ouchi, Torsten Albrecht, Jorge Alvarez‐Solas, Xylar S. Asay‐Davis, Jean‐Baptiste Barre, Constantijn J. Berends, Jorge Bernales, Javier Blasco, Justine Caillet, David M. Chandler, Violaine Coulon, Richard Cullather, Christophe Dumas, Benjamin K. Galton‐Fenzi, Julius Garbe, Fabien Gillet‐Chaulet, Rupert Gladstone, Heiko Goelzer, Nicholas R. Golledge, Ralf Greve, G. Hilmar Gudmundsson, Holly Kyeore Han, Trevor R. Hillebrand, Matthew J. Hoffman, Philippe Huybrechts, Nicolas C. Jourdain, Ann Kristin Klose, Petra M. Langebroek, Gunter R. Leguy, William H. Lipscomb, Daniel P. Lowry, Pierre Mathiot, Marisa Montoya, Mathieu Morlighem, Sophie Nowicki, Frank Pattyn, Antony J. Payne, Tyler Pelle, Aurélien Quiquet, Alexander Robinson, Leopekka Saraste, Erika G. Simon, Sainan Sun, Jake P. Twarog, Luke D. Trusel, Benoit Urruty, Jonas Van Breedam, Roderik S. W. van de Wal, Chen Zhao, and Thomas Zwinger
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Jan De Rydt, Nicolas C. Jourdain, Yoshihiro Nakayama, Mathias van Caspel, Ralph Timmermann, Pierre Mathiot, Xylar S. Asay-Davis, Hélène Seroussi, Pierre Dutrieux, Ben Galton-Fenzi, David Holland, and Ronja Reese
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Pierre Mathiot and Nicolas C. Jourdain
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How much the Antarctic ice shelf basal melt rate can increase in response to global warming remains an open question. To achieve this, we compared an ocean simulation under present-day atmospheric condition to a one under late 23rd century atmospheric conditions. The ocean response to the perturbation includes a decrease in the production of cold dense water and an increased intrusion of warmer water onto the continental shelves. This induces a substantial increase in ice shelf basal melt rates.
Jonathan Wiskandt, Inga Monika Koszalka, and Johan Nilsson
The Cryosphere, 17, 2755–2777, https://doi.org/10.5194/tc-17-2755-2023, https://doi.org/10.5194/tc-17-2755-2023, 2023
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Understanding ice–ocean interactions under floating ice tongues in Greenland and Antarctica is a major challenge in climate modelling and a source of uncertainty in future sea level projections. We use a high-resolution ocean model to investigate basal melting and melt-driven circulation under the floating tongue of Ryder Glacier, northwestern Greenland. We study the response to oceanic and atmospheric warming. Our results are universal and relevant for the development of climate models.
Katherine Hutchinson, Julie Deshayes, Christian Éthé, Clément Rousset, Casimir de Lavergne, Martin Vancoppenolle, Nicolas C. Jourdain, and Pierre Mathiot
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Bottom Water constitutes the lower half of the ocean’s overturning system and is primarily formed in the Weddell and Ross Sea in the Antarctic due to interactions between the atmosphere, ocean, sea ice and ice shelves. Here we use a global ocean 1° resolution model with explicit representation of the three large ice shelves important for the formation of the parent waters of Bottom Water. We find doing so reduces salt biases, improves water mass realism and gives realistic ice shelf melt rates.
Clara Burgard, Nicolas C. Jourdain, Ronja Reese, Adrian Jenkins, and Pierre Mathiot
The Cryosphere, 16, 4931–4975, https://doi.org/10.5194/tc-16-4931-2022, https://doi.org/10.5194/tc-16-4931-2022, 2022
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The ocean-induced melt at the base of the floating ice shelves around Antarctica is one of the largest uncertainty factors in the Antarctic contribution to future sea-level rise. We assess the performance of several existing parameterisations in simulating basal melt rates on a circum-Antarctic scale, using an ocean simulation resolving the cavities below the shelves as our reference. We find that the simple quadratic slope-independent and plume parameterisations yield the best compromise.
Christoph Kittel, Charles Amory, Stefan Hofer, Cécile Agosta, Nicolas C. Jourdain, Ella Gilbert, Louis Le Toumelin, Étienne Vignon, Hubert Gallée, and Xavier Fettweis
The Cryosphere, 16, 2655–2669, https://doi.org/10.5194/tc-16-2655-2022, https://doi.org/10.5194/tc-16-2655-2022, 2022
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Model projections suggest large differences in future Antarctic surface melting even for similar greenhouse gas scenarios and warming rates. We show that clouds containing a larger amount of liquid water lead to stronger melt. As surface melt can trigger the collapse of the ice shelves (the safety band of the Antarctic Ice Sheet), clouds could be a major source of uncertainties in projections of sea level rise.
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Short summary
In ocean models, submarine melt of ice shelves is parameterized based on the heat budget at the ice–ocean interface. The heat budget includes the ocean heat transport, the heat conducted into the ice, and the heat available for melting. Here we compare three different approaches to estimating the heat conduction into the ice. We show that the most used approximation is not the most accurate one: it overestimates the melt by up to 25 % compared to the more accurate approximations.
In ocean models, submarine melt of ice shelves is parameterized based on the heat budget at the...
