Articles | Volume 20, issue 1
https://doi.org/10.5194/tc-20-135-2026
© Author(s) 2026. 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-20-135-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
08 Jan 2026
Research article |
| 08 Jan 2026
| 08 Jan 2026
Modelled dynamics of floating and grounded icebergs, with application to the Amundsen Sea
British Antarctic Survey, Cambridge, UK
Paul R. Holland
British Antarctic Survey, Cambridge, UK
Kelly A. Hogan
British Antarctic Survey, Cambridge, UK
James A. Smith
British Antarctic Survey, Cambridge, UK
Nicolas C. Jourdain
Univ. Grenoble Alpes/CNRS/IRD/G-INP/INRAE, Institut des Géosciences de l'Environnement, Grenoble, France
Pierre Mathiot
Univ. Grenoble Alpes/CNRS/IRD/G-INP/INRAE, Institut des Géosciences de l'Environnement, Grenoble, France
Anna Olivé Abelló
Univ. Grenoble Alpes/CNRS/IRD/G-INP/INRAE, Institut des Géosciences de l'Environnement, Grenoble, France
Andrew H. Fleming
British Antarctic Survey, Cambridge, UK
Andrew J. S. Meijers
British Antarctic Survey, Cambridge, UK
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Anna Olivé Abelló, Pierre Mathiot, Nicolas C. Jourdain, Yavor Kostov, and Paul R. Holland
EGUsphere, https://doi.org/10.5194/egusphere-2026-3422, https://doi.org/10.5194/egusphere-2026-3422, 2026
This preprint is open for discussion and under review for Ocean Science (OS).
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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.
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson
Ocean Sci., 20, 521–547, https://doi.org/10.5194/os-20-521-2024, https://doi.org/10.5194/os-20-521-2024, 2024
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We examine factors affecting variability in the volume of Labrador Sea Water (LSW), a water mass that is important for the uptake and storage of heat and carbon in the Atlantic Ocean. We find that LSW accumulated in the Labrador Sea exhibits a lagged response to remote conditions: surface wind stress, heat flux, and freshwater flux anomalies, especially along the pathways of the North Atlantic Current branches. We use our results to reconstruct and attribute historical changes in LSW volume.
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The Cryosphere, 20, 3443–3465, https://doi.org/10.5194/tc-20-3443-2026, https://doi.org/10.5194/tc-20-3443-2026, 2026
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At least since we began measuring in detail, the West Antarctic Ice Sheet has lost a lot of ice, but we don't know precisely how important climate change is in this. Here, we put a number on the role of climate change in retreat of a glacier in this ice sheet, for the first time. We show that climate change made the shrinking of this glacier much worse. Our work also suggests that what happened on very long timescales (the last 10,000 years) might also matter for retreat of the ice sheets today.
Anna Olivé Abelló, Pierre Mathiot, Nicolas C. Jourdain, Yavor Kostov, and Paul R. Holland
EGUsphere, https://doi.org/10.5194/egusphere-2026-3422, https://doi.org/10.5194/egusphere-2026-3422, 2026
This preprint is open for discussion and under review for Ocean Science (OS).
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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.
Luisa E. Avilés-Podgurski, Patrick Martineau, Hua Lu, Ayako Yamamoto, Amanda C. Maycock, Andrew Orr, Tony Phillips, Thomas J. Bracegirdle, Anna E. Hogg, Grzegorz Muszynski, and Andrew Fleming
Weather Clim. Dynam., 7, 1051–1071, https://doi.org/10.5194/wcd-7-1051-2026, https://doi.org/10.5194/wcd-7-1051-2026, 2026
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Atmospheric rivers (ARs) are narrow filaments of intense poleward water vapour transport. On rare occasions, they reach the Arctic, driving strong warming and melt. In April 2020, two ARs intruded into the central Arctic within one week, raising near-surface temperatures by up to 30°C and leading to extreme precipitation. Their distinct paths and thermodynamic evolution reveal diverse AR impacts on Arctic sea ice and precipitation extremes.
Paul Holland, Adrian Jenkins, David Bett, and Suzanne Bevan
EGUsphere, https://doi.org/10.5194/egusphere-2026-2835, https://doi.org/10.5194/egusphere-2026-2835, 2026
This preprint is open for discussion and under review for The Cryosphere (TC).
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Ice loss from the Amundsen Sea sector of the Antarctic Ice Sheet is a major contributor to global sea-level rise. In this study we use ocean simulations to understand the ice melting in this sector. The strongest melting is focussed on deep ice where the glaciers flow into the ocean. Secondary areas of melting occur beneath meltwater currents. The simulations are used to test simple mathematical representations of melting that could be built into an ice sheet model.
Robin S. Smith, Tarkan A. Bilge, Thomas J. Bracegirdle, Paul R. Holland, Till Kuhlbrodt, Charlotte Lang, Spencer Liddicoat, Tom Mitcham, Jane Mulcahy, Kaitlin A. Naughten, Andrew Orr, Julien Palmieri, Antony J. Payne, Steven Rumbold, Marc Stringer, Ranjini Swaminathan, Sarah Taylor, Jeremy Walton, and Colin Jones
Earth Syst. Dynam., 17, 475–493, https://doi.org/10.5194/esd-17-475-2026, https://doi.org/10.5194/esd-17-475-2026, 2026
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There is a dangerous amount of uncertainty in our predictions of climate change in polar regions because some of feedbacks that might lead to changes that are too rapid for us to adapt to, or that cannot be reversed. We have run a set of simulations with a state-of-the-art Earth System Model that helps improve our understanding of how climate in these regions might change. Some of the aspects we investigate are reversible but many are not, especially those affecting ice sheets and sea level.
Torge Martin, Carolina O. Dufour, Andrew J. S. Meijers, and Alyce M. Hancock
Ocean Sci., 22, 1429–1437, https://doi.org/10.5194/os-22-1429-2026, https://doi.org/10.5194/os-22-1429-2026, 2026
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In the next 7 years major observational programs will be launched to improve our understanding of the Southern Ocean, the changes it is experiencing and its role in global warming. For these to advance current knowledge, we believe intense exchange with the numerical modelling community is essential. The survey results presented help to identify urgently needed observations for model development and underline the importance to explore new avenues in communication, collaboration and education.
Claire K. Yung, Xylar S. Asay-Davis, Alistair Adcroft, Christopher Y. S. Bull, Jan De Rydt, Michael S. Dinniman, Benjamin K. Galton-Fenzi, Daniel Goldberg, David E. Gwyther, Robert Hallberg, Matthew Harrison, Tore Hattermann, David M. Holland, Denise Holland, Paul R. Holland, James R. Jordan, Nicolas C. Jourdain, Kazuya Kusahara, Gustavo Marques, Pierre Mathiot, Dimitris Menemenlis, Adele K. Morrison, Yoshihiro Nakayama, Olga Sergienko, Robin S. Smith, Alon Stern, Ralph Timmermann, and Qin Zhou
The Cryosphere, 20, 2053–2088, https://doi.org/10.5194/tc-20-2053-2026, https://doi.org/10.5194/tc-20-2053-2026, 2026
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The second Ice Shelf-Ocean Model Intercomparison Project, ISOMIP+, compares 12 ice shelf-ocean models with a common, idealised, static configuration, aiming to assess inter-model variability. Models show similar basal melt rate patterns, ocean profiles and circulation but differ in ice-ocean boundary layer properties. Ice-ocean boundary layer representation is a key area for future work, as are realistic-domain ice sheet-ocean model intercomparisons.
Dorothée Vallot, Nicolas C. Jourdain, and Pierre Mathiot
The Cryosphere, 20, 1997–2016, https://doi.org/10.5194/tc-20-1997-2026, https://doi.org/10.5194/tc-20-1997-2026, 2026
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Some recent studies show that the topography at the base of an ice shelf has consequences for its interaction with the ocean. To describe friction velocity in the melt parameterisation, we use a drag coefficient dependent on the distance of the first wet cell to the ice and the basal topography rather than a fixed-tuned parameter. We find that it is less dependent on the choice of vertical resolution and, while providing similar total melt, it gives more weight to highly crevassed areas.
Pierre Mathiot, Nicolas C. Jourdain, Benoit Urruty, Fabien Gillet-Chaulet, Olivier Gagliardini, and Gaël Durand
EGUsphere, https://doi.org/10.5194/egusphere-2026-927, https://doi.org/10.5194/egusphere-2026-927, 2026
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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.
Helen Ockenden, Clara Burgard, Pierre Mathiot, Christoph Kittel, Achille Gellens, Cécile Agosta, and Nicolas C. Jourdain
EGUsphere, https://doi.org/10.5194/egusphere-2025-6314, https://doi.org/10.5194/egusphere-2025-6314, 2026
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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.
David T. Bett, Alexander T. Bradley, Bertie W. J. Miles, C. Rosie Williams, Paul R. Holland, and Robert J. Arthern
EGUsphere, https://doi.org/10.5194/egusphere-2026-669, https://doi.org/10.5194/egusphere-2026-669, 2026
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An ice-ocean model is used to explore the 20th-century evolution of Thwaites Glacier, Antarctica. Several processes are involved as the ice retreats to its present-day state, including ocean melting, the floatation of a historically-grounded ice island, ice crevassing and damage, and changing of ice-flow patterns. Multiple options for steady historical Thwaites Glacier configurations are found, with these options compared against 1940s aerial imagery and evidence from seabed sediments.
Benjamin Heurgue, Charles Amory, Christoph Kittel, Fredrik Boberg, Gaël Durand, Vincent Favier, Xavier Fettweis, Quentin Glaude, Heiko Goelzer, Nicolaj Hansen, Nicolas C. Jourdain, Ruth Mottram, Martin Olesen, Willem Jan Van de Berg, Michiel R. Van den Broeke, and René R. Wijngaard
EGUsphere, https://doi.org/10.5194/egusphere-2026-624, https://doi.org/10.5194/egusphere-2026-624, 2026
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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.
Ben R. Evans, Alan R. Lowe, Anna Crawford, Andrew Fleming, and J. Scott Hosking
The Cryosphere, 20, 467–482, https://doi.org/10.5194/tc-20-467-2026, https://doi.org/10.5194/tc-20-467-2026, 2026
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Icebergs account for about half of the freshwater lost from Antarctica. Because they can drift for long periods of time and across great distances, it is hard to know where in the oceans that water ends up, yet this is crucially important for ocean circulations and the global climate. We have developed a digital tool that can help us to understand the dynamics and effects of icebergs by recognizing them through time and doing “jigsaw puzzles” to reconstruct their family trees when they break apart.
Kevin Hank, Robert J. Arthern, C. Rosie Williams, Alex M. Brisbourne, Andrew M. Smith, James A. Smith, Anna Wåhlin, and Sridhar Anandakrishnan
The Cryosphere, 20, 495–510, https://doi.org/10.5194/tc-20-495-2026, https://doi.org/10.5194/tc-20-495-2026, 2026
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The slipperiness at the ice base is a key uncertainty in sea level rise projections. Alternative formulations of the sliding law exist, but limited access to the ice base makes it difficult to validate them. We introduce a new approach using observations and model output to infer a basal sliding law. For Pine Island Glacier, currently the largest single contributor to sea level rise in Antarctica, the results provide support for a Coulomb-type sliding law and widespread low effective pressures.
Tom A. Jordan, Karen J. Heywood, Anna Wåhlin, Rob A. Hall, Atsuhiro Muto, Pierre Dutrieux, Kelly Hogan, James Girton, Karen E. Alley, and Erin Pettit
EGUsphere, https://doi.org/10.5194/egusphere-2025-6001, https://doi.org/10.5194/egusphere-2025-6001, 2026
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The shape of the water filled cavity hidden beneath ice shelves is extremely important, but hard to measure. Gravity data collected from aircraft can be used to predict the shape. However, in the Dotson Crosson ice shelves in West Antarctica, new direct observations from autonomous platforms sent beneath the ice, and seismic observations from the ice surface showed gravity models were systematically too shallow. We explain why and provide a solution applicable her and in other ice shelves.
Shenjie Zhou, Pierre Dutrieux, Claudia Giulivi, Andrew Meijers, Won Sang Lee, Tae-Wan Kim, Tore Hattermann, and Markus Janout
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2025-727, https://doi.org/10.5194/essd-2025-727, 2026
Revised manuscript under review for ESSD
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A collection of temperature and salinity measurements made in the Southern Ocean and around Antarctic continental shelf seas is assembled and described in this paper. A gridded product developed out of these scattered data points is also described. The gridded product provide us a better view of contemporary mean status of the Southern Ocean and Antarctic shelf seas and help models to better reference the prediction of the future climate.
Gavin A. Schmidt, Kenneth D. Mankoff, Jonathan L. Bamber, Clara Burgard, Dustin Carroll, David M. Chandler, Violaine Coulon, Benjamin J. Davison, Matthew H. England, Paul R. Holland, Nicolas C. Jourdain, Qian Li, Juliana M. Marson, Pierre Mathiot, Clive R. McMahon, Twila A. Moon, Ruth Mottram, Sophie Nowicki, Anna Olivé Abelló, Andrew G. Pauling, Thomas Rackow, and Damien Ringeisen
Geosci. Model Dev., 18, 8333–8361, https://doi.org/10.5194/gmd-18-8333-2025, https://doi.org/10.5194/gmd-18-8333-2025, 2025
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The impact of increasing mass loss from the Greenland and Antarctic ice sheets has not so far been included in historical climate model simulations. This paper describes the protocols and data available for modeling groups to add this anomalous freshwater to their ocean modules to better represent the impacts of these fluxes on ocean circulation, sea ice, salinity and sea level.
Katie Lowery, Pierre Dutrieux, Paul R. Holland, Anna E. Hogg, Noel Gourmelen, and Benjamin J. Wallis
The Cryosphere, 19, 4893–4911, https://doi.org/10.5194/tc-19-4893-2025, https://doi.org/10.5194/tc-19-4893-2025, 2025
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Using CryoSat-2, we observe monthly changes in the Pine Island Glacier (PIG) ice shelf surface and derive oceanic melt at its base. Basal channels, kilometres wide, are reflected in the ice surface and captured in our observations. We demonstrate that melt is concentrated on the western walls of channels, that channels play a role in grounding pinning points, and that PIG's main channel geometry is inherited upstream of the grounding line. These results highlight the importance of channels to ice shelf stability.
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
EGUsphere, https://doi.org/10.5194/egusphere-2025-4069, https://doi.org/10.5194/egusphere-2025-4069, 2025
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Antarctica holds enough ice to raise sea levels by many meters, but its future is uncertain. Warm ocean water melts ice shelves from below, letting inland ice flow faster into the sea. By 2300, Antarctica could add 0.6–4.4 m to sea levels. Our study identifies two key factors—how strongly shelves melt and how the ice responds. These explain much of the range, and refining them in models may improve future predictions.
Jonathan Wiskandt and Nicolas C. Jourdain
The Cryosphere, 19, 3253–3258, https://doi.org/10.5194/tc-19-3253-2025, https://doi.org/10.5194/tc-19-3253-2025, 2025
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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.
Cyrille Mosbeux, Peter Råback, Adrien Gilbert, Julien Brondex, Fabien Gillet-Chaulet, Nicolas C. Jourdain, Mondher Chekki, Olivier Gagliardini, and Gaël Durand
EGUsphere, https://doi.org/10.5194/egusphere-2025-3039, https://doi.org/10.5194/egusphere-2025-3039, 2025
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Transport processes like rocks carried by ice flow and damage evolution – a proxy for crevasses – are key in ice sheet modeling and should occur without diffusion. Yet, standard numerical methods often blur these features. We explore a particle-based Semi-Lagrangian approach, comparing it to a Discontinuous Galerkin method, and show it can accurately simulate such transport when run at high enough resolution.
Ciara Pimm, Andrew J. S. Meijers, Dani C. Jones, and Richard G. Williams
Ocean Sci., 21, 1237–1253, https://doi.org/10.5194/os-21-1237-2025, https://doi.org/10.5194/os-21-1237-2025, 2025
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Subantarctic mode water in the South Pacific Ocean is important due to its role in the uptake and transport of anthropogenic heat and carbon. The Subantarctic mode water region can be split into two pools using mixed-layer-depth properties. Sensitivity experiments are used to understand the effects of heating and wind on each pool. It is found that the optimal conditions to form large amounts of Subantarctic mode water in the South Pacific are local cooling and upstream warming combined.
David Storkey, Pierre Mathiot, Michael J. Bell, Dan Copsey, Catherine Guiavarc'h, Helene T. Hewitt, Jeff Ridley, and Malcolm J. Roberts
Geosci. Model Dev., 18, 2725–2745, https://doi.org/10.5194/gmd-18-2725-2025, https://doi.org/10.5194/gmd-18-2725-2025, 2025
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The Southern Ocean is a key region of the world ocean in the context of climate change studies. We show that the Met Office Hadley Centre coupled model with intermediate ocean resolution struggles to accurately simulate the Southern Ocean. Increasing the frictional drag that the seafloor exerts on ocean currents and introducing a representation of unresolved ocean eddies both appear to reduce the large-scale biases in this model.
Nicolas C. Jourdain, Charles Amory, Christoph Kittel, and Gaël Durand
The Cryosphere, 19, 1641–1674, https://doi.org/10.5194/tc-19-1641-2025, https://doi.org/10.5194/tc-19-1641-2025, 2025
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A mixed statistical–physical approach is used to reproduce the behaviour of a regional climate model. From that, we estimate the contribution of snowfall and melting at the surface of the Antarctic Ice Sheet to changes in global mean sea level. We also investigate the impact of surface melting in a warmer climate on the stability of the Antarctic ice shelves that provide back stress on the ice flow to the ocean.
Asmara A. Lehrmann, Rebecca L. Totten, Julia S. Wellner, Claus-Dieter Hillenbrand, Svetlana Radionovskaya, R. Michael Comas, Robert D. Larter, Alastair G. C. Graham, James D. Kirkham, Kelly A. Hogan, Victoria Fitzgerald, Rachel W. Clark, Becky Hopkins, Allison P. Lepp, Elaine Mawbey, Rosemary V. Smyth, Lauren E. Miller, James A. Smith, and Frank O. Nitsche
J. Micropalaeontol., 44, 79–105, https://doi.org/10.5194/jm-44-79-2025, https://doi.org/10.5194/jm-44-79-2025, 2025
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Thwaites Glacier's retreat is driven by warm ocean water melting its ice shelf. Seafloor-dwelling marine protists, benthic foraminifera, reflect their environment. Here, ice margins, oceanography, and sea ice cover control live foraminiferal populations. Including dead foraminifera in the analyses shows the calcareous test preservation's role in the assemblage make-up. Understanding these modern communities helps interpret past glacial retreat controls through foraminifera in sediment records.
Justine Caillet, Nicolas C. Jourdain, Pierre Mathiot, Fabien Gillet-Chaulet, Benoit Urruty, Clara Burgard, Charles Amory, Mondher Chekki, and Christoph Kittel
Earth Syst. Dynam., 16, 293–315, https://doi.org/10.5194/esd-16-293-2025, https://doi.org/10.5194/esd-16-293-2025, 2025
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Internal climate variability, resulting from processes intrinsic to the climate system, modulates the Antarctic response to climate change by delaying or offsetting its effects. Using climate and ice-sheet models, we highlight that irreducible internal climate variability significantly enlarges the likely range of Antarctic contribution to sea-level rise until 2100. Thus, we recommend considering internal climate variability as a source of uncertainty for future ice-sheet projections.
Catherine Guiavarc'h, David Storkey, Adam T. Blaker, Ed Blockley, Alex Megann, Helene Hewitt, Michael J. Bell, Daley Calvert, Dan Copsey, Bablu Sinha, Sophia Moreton, Pierre Mathiot, and Bo An
Geosci. Model Dev., 18, 377–403, https://doi.org/10.5194/gmd-18-377-2025, https://doi.org/10.5194/gmd-18-377-2025, 2025
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The Global Ocean and Sea Ice configuration version 9 (GOSI9) is the new UK hierarchy of model configurations based on the Nucleus for European Modelling of the Ocean (NEMO) and available at three resolutions. It will be used for various applications, e.g. weather forecasting and climate prediction. It improves upon the previous version by reducing global temperature and salinity biases and enhancing the representation of Arctic sea ice and the Antarctic Circumpolar Current.
Caroline R. Holmes, Thomas J. Bracegirdle, Paul R. Holland, Julienne Stroeve, and Jeremy Wilkinson
The Cryosphere, 18, 5641–5652, https://doi.org/10.5194/tc-18-5641-2024, https://doi.org/10.5194/tc-18-5641-2024, 2024
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Until recently, satellite data showed an increase in Antarctic sea ice area since 1979, but climate models simulated a decrease over this period. This mismatch was one reason for low confidence in model projections of 21st-century sea ice loss. We show that following low Antarctic sea ice in 2022 and 2023, we can no longer conclude that modelled and observed trends differ. However, differences in the manner of the decline mean that model sea ice projections should still be viewed with caution.
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
Geosci. Model Dev., 17, 7105–7139, https://doi.org/10.5194/gmd-17-7105-2024, https://doi.org/10.5194/gmd-17-7105-2024, 2024
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Global climate models do not reliably simulate sea-level change due to ice-sheet–ocean interactions. We propose a community modelling effort to conduct a series of well-defined experiments to compare models with observations and study how models respond to a range of perturbations in climate and ice-sheet geometry. The second Marine Ice Sheet–Ocean Model Intercomparison Project will continue to lay the groundwork for including ice-sheet–ocean interactions in global-scale IPCC-class models.
Indrani Das, Jowan Barnes, James Smith, Renata Constantino, Sidney Hemming, and Laurie Padman
EGUsphere, https://doi.org/10.5194/egusphere-2024-1564, https://doi.org/10.5194/egusphere-2024-1564, 2024
Preprint archived
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George VI Ice Shelf (GVIIS) on the Antarctic Peninsula is currently thinning and the glaciers feeding it are accelerating. Geologic evidence indicates that GVIIS had disintegrated several thousand years ago due to ocean and atmosphere warming. Here, we use remote sensing and numerical modeling to show that strain thinning reduces buttressing of grounded ice, creating a positive feedback of accelerated ice inflow to the southern GVIIS, likely making it more vulnerable than the northern sector.
David T. Bett, Alexander T. Bradley, C. Rosie Williams, Paul R. Holland, Robert J. Arthern, and Daniel N. Goldberg
The Cryosphere, 18, 2653–2675, https://doi.org/10.5194/tc-18-2653-2024, https://doi.org/10.5194/tc-18-2653-2024, 2024
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A new ice–ocean model simulates future ice sheet evolution in the Amundsen Sea sector of Antarctica. Substantial ice retreat is simulated in all scenarios, with some retreat still occurring even with no future ocean melting. The future of small "pinning points" (islands of ice that contact the seabed) is an important control on this retreat. Ocean melting is crucial in causing these features to go afloat, providing the link by which climate change may affect this sector's sea level contribution.
Allison P. Lepp, Lauren E. Miller, John B. Anderson, Matt O'Regan, Monica C. M. Winsborrow, James A. Smith, Claus-Dieter Hillenbrand, Julia S. Wellner, Lindsay O. Prothro, and Evgeny A. Podolskiy
The Cryosphere, 18, 2297–2319, https://doi.org/10.5194/tc-18-2297-2024, https://doi.org/10.5194/tc-18-2297-2024, 2024
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Shape and surface texture of silt-sized grains are measured to connect marine sediment records with subglacial water flow. We find that grain shape alteration is greatest in glaciers where high-energy drainage events and abundant melting of surface ice are inferred and that the surfaces of silt-sized sediments preserve evidence of glacial transport. Our results suggest grain shape and texture may reveal whether glaciers previously experienced temperate conditions with more abundant meltwater.
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson
Ocean Sci., 20, 521–547, https://doi.org/10.5194/os-20-521-2024, https://doi.org/10.5194/os-20-521-2024, 2024
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We examine factors affecting variability in the volume of Labrador Sea Water (LSW), a water mass that is important for the uptake and storage of heat and carbon in the Atlantic Ocean. We find that LSW accumulated in the Labrador Sea exhibits a lagged response to remote conditions: surface wind stress, heat flux, and freshwater flux anomalies, especially along the pathways of the North Atlantic Current branches. We use our results to reconstruct and attribute historical changes in LSW volume.
Hélène Seroussi, Vincent Verjans, Sophie Nowicki, Antony J. Payne, Heiko Goelzer, William H. Lipscomb, Ayako Abe-Ouchi, Cécile Agosta, Torsten Albrecht, Xylar Asay-Davis, Alice Barthel, Reinhard Calov, Richard Cullather, Christophe Dumas, Benjamin K. Galton-Fenzi, Rupert Gladstone, Nicholas R. Golledge, Jonathan M. Gregory, Ralf Greve, Tore Hattermann, Matthew J. Hoffman, Angelika Humbert, Philippe Huybrechts, Nicolas C. Jourdain, Thomas Kleiner, Eric Larour, Gunter R. Leguy, Daniel P. Lowry, Chistopher M. Little, Mathieu Morlighem, Frank Pattyn, Tyler Pelle, Stephen F. Price, Aurélien Quiquet, Ronja Reese, Nicole-Jeanne Schlegel, Andrew Shepherd, Erika Simon, Robin S. Smith, Fiammetta Straneo, Sainan Sun, Luke D. Trusel, Jonas Van Breedam, Peter Van Katwyk, Roderik S. W. van de Wal, Ricarda Winkelmann, Chen Zhao, Tong Zhang, and Thomas Zwinger
The Cryosphere, 17, 5197–5217, https://doi.org/10.5194/tc-17-5197-2023, https://doi.org/10.5194/tc-17-5197-2023, 2023
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Mass loss from Antarctica is a key contributor to sea level rise over the 21st century, and the associated uncertainty dominates sea level projections. We highlight here the Antarctic glaciers showing the largest changes and quantify the main sources of uncertainty in their future evolution using an ensemble of ice flow models. We show that on top of Pine Island and Thwaites glaciers, Totten and Moscow University glaciers show rapid changes and a strong sensitivity to warmer ocean conditions.
Pierre Mathiot and Nicolas C. Jourdain
Ocean Sci., 19, 1595–1615, https://doi.org/10.5194/os-19-1595-2023, https://doi.org/10.5194/os-19-1595-2023, 2023
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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.
Gemma K. O'Connor, Paul R. Holland, Eric J. Steig, Pierre Dutrieux, and Gregory J. Hakim
The Cryosphere, 17, 4399–4420, https://doi.org/10.5194/tc-17-4399-2023, https://doi.org/10.5194/tc-17-4399-2023, 2023
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Glaciers in West Antarctica are rapidly melting, but the causes are unknown due to limited observations. A leading hypothesis is that an unusually large wind event in the 1940s initiated the ocean-driven melting. Using proxy reconstructions (e.g., using ice cores) and climate model simulations, we find that wind events similar to the 1940s event are relatively common on millennial timescales, implying that ocean variability or climate trends are also necessary to explain the start of ice loss.
Erwin Lambert, André Jüling, Roderik S. W. van de Wal, and Paul R. Holland
The Cryosphere, 17, 3203–3228, https://doi.org/10.5194/tc-17-3203-2023, https://doi.org/10.5194/tc-17-3203-2023, 2023
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A major uncertainty in the study of sea level rise is the melting of the Antarctic ice sheet by the ocean. Here, we have developed a new model, named LADDIE, that simulates this ocean-driven melting of the floating parts of the Antarctic ice sheet. This model simulates fine-scale patterns of melting and freezing and requires significantly fewer computational resources than state-of-the-art ocean models. LADDIE can be used as a new tool to force high-resolution ice sheet models.
Kelly A. Hogan, Katarzyna L. P. Warburton, Alastair G. C. Graham, Jerome A. Neufeld, Duncan R. Hewitt, Julian A. Dowdeswell, and Robert D. Larter
The Cryosphere, 17, 2645–2664, https://doi.org/10.5194/tc-17-2645-2023, https://doi.org/10.5194/tc-17-2645-2023, 2023
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Delicate sea floor ridges – corrugation ridges – that form by tidal motion at Antarctic grounding lines record extremely fast retreat of ice streams in the past. Here we use a mathematical model, constrained by real-world observations from Thwaites Glacier, West Antarctica, to explore how corrugation ridges form. We identify
till extrusion, whereby deformable sediment is squeezed out from under the ice like toothpaste as it settles down at each low-tide position, as the most likely process.
Katherine Hutchinson, Julie Deshayes, Christian Éthé, Clément Rousset, Casimir de Lavergne, Martin Vancoppenolle, Nicolas C. Jourdain, and Pierre Mathiot
Geosci. Model Dev., 16, 3629–3650, https://doi.org/10.5194/gmd-16-3629-2023, https://doi.org/10.5194/gmd-16-3629-2023, 2023
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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.
Dani C. Jones, Maike Sonnewald, Shenjie Zhou, Ute Hausmann, Andrew J. S. Meijers, Isabella Rosso, Lars Boehme, Michael P. Meredith, and Alberto C. Naveira Garabato
Ocean Sci., 19, 857–885, https://doi.org/10.5194/os-19-857-2023, https://doi.org/10.5194/os-19-857-2023, 2023
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Machine learning is transforming oceanography. For example, unsupervised classification approaches help researchers identify underappreciated structures in ocean data, helping to generate new hypotheses. In this work, we use a type of unsupervised classification to identify structures in the temperature and salinity structure of the Weddell Gyre, which is an important region for global ocean circulation and for climate. We use our method to generate new ideas about mixing in the Weddell Gyre.
Michael J. Bentley, James A. Smith, Stewart S. R. Jamieson, Margaret R. Lindeman, Brice R. Rea, Angelika Humbert, Timothy P. Lane, Christopher M. Darvill, Jeremy M. Lloyd, Fiamma Straneo, Veit Helm, and David H. Roberts
The Cryosphere, 17, 1821–1837, https://doi.org/10.5194/tc-17-1821-2023, https://doi.org/10.5194/tc-17-1821-2023, 2023
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The Northeast Greenland Ice Stream is a major outlet of the Greenland Ice Sheet. Some of its outlet glaciers and ice shelves have been breaking up and retreating, with inflows of warm ocean water identified as the likely reason. Here we report direct measurements of warm ocean water in an unusual lake that is connected to the ocean beneath the ice shelf in front of the 79° N Glacier. This glacier has not yet shown much retreat, but the presence of warm water makes future retreat more likely.
James A. Smith, Louise Callard, Michael J. Bentley, Stewart S. R. Jamieson, Maria Luisa Sánchez-Montes, Timothy P. Lane, Jeremy M. Lloyd, Erin L. McClymont, Christopher M. Darvill, Brice R. Rea, Colm O'Cofaigh, Pauline Gulliver, Werner Ehrmann, Richard S. Jones, and David H. Roberts
The Cryosphere, 17, 1247–1270, https://doi.org/10.5194/tc-17-1247-2023, https://doi.org/10.5194/tc-17-1247-2023, 2023
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The Greenland Ice Sheet is melting at an accelerating rate. To understand the significance of these changes we reconstruct the history of one of its fringing ice shelves, known as 79° N ice shelf. We show that the ice shelf disappeared 8500 years ago, following a period of enhanced warming. An important implication of our study is that 79° N ice shelf is susceptible to collapse when atmospheric and ocean temperatures are ~2°C warmer than present, which could occur by the middle of this century.
Jeff Polton, James Harle, Jason Holt, Anna Katavouta, Dale Partridge, Jenny Jardine, Sarah Wakelin, Julia Rulent, Anthony Wise, Katherine Hutchinson, David Byrne, Diego Bruciaferri, Enda O'Dea, Michela De Dominicis, Pierre Mathiot, Andrew Coward, Andrew Yool, Julien Palmiéri, Gennadi Lessin, Claudia Gabriela Mayorga-Adame, Valérie Le Guennec, Alex Arnold, and Clément Rousset
Geosci. Model Dev., 16, 1481–1510, https://doi.org/10.5194/gmd-16-1481-2023, https://doi.org/10.5194/gmd-16-1481-2023, 2023
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The aim is to increase the capacity of the modelling community to respond to societally important questions that require ocean modelling. The concept of reproducibility for regional ocean modelling is developed: advocating methods for reproducible workflows and standardised methods of assessment. Then, targeting the NEMO framework, we give practical advice and worked examples, highlighting key considerations that will the expedite development cycle and upskill the user community.
Paul R. Holland, Gemma K. O'Connor, Thomas J. Bracegirdle, Pierre Dutrieux, Kaitlin A. Naughten, Eric J. Steig, David P. Schneider, Adrian Jenkins, and James A. Smith
The Cryosphere, 16, 5085–5105, https://doi.org/10.5194/tc-16-5085-2022, https://doi.org/10.5194/tc-16-5085-2022, 2022
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The Antarctic Ice Sheet is losing ice, causing sea-level rise. However, it is not known whether human-induced climate change has contributed to this ice loss. In this study, we use evidence from climate models and palaeoclimate measurements (e.g. ice cores) to suggest that the ice loss was triggered by natural climate variations but is now sustained by human-forced climate change. This implies that future greenhouse-gas emissions may influence sea-level rise from Antarctica.
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.
Antony Siahaan, Robin S. Smith, Paul R. Holland, Adrian Jenkins, Jonathan M. Gregory, Victoria Lee, Pierre Mathiot, Antony J. Payne, Jeff K. Ridley, and Colin G. Jones
The Cryosphere, 16, 4053–4086, https://doi.org/10.5194/tc-16-4053-2022, https://doi.org/10.5194/tc-16-4053-2022, 2022
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The UK Earth System Model is the first to fully include interactions of the atmosphere and ocean with the Antarctic Ice Sheet. Under the low-greenhouse-gas SSP1–1.9 (Shared Socioeconomic Pathway) scenario, the ice sheet remains stable over the 21st century. Under the strong-greenhouse-gas SSP5–8.5 scenario, the model predicts strong increases in melting of large ice shelves and snow accumulation on the surface. The dominance of accumulation leads to a sea level fall at the end of the century.
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.
Charles Pelletier, Thierry Fichefet, Hugues Goosse, Konstanze Haubner, Samuel Helsen, Pierre-Vincent Huot, Christoph Kittel, François Klein, Sébastien Le clec'h, Nicole P. M. van Lipzig, Sylvain Marchi, François Massonnet, Pierre Mathiot, Ehsan Moravveji, Eduardo Moreno-Chamarro, Pablo Ortega, Frank Pattyn, Niels Souverijns, Guillian Van Achter, Sam Vanden Broucke, Alexander Vanhulle, Deborah Verfaillie, and Lars Zipf
Geosci. Model Dev., 15, 553–594, https://doi.org/10.5194/gmd-15-553-2022, https://doi.org/10.5194/gmd-15-553-2022, 2022
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We present PARASO, a circumpolar model for simulating the Antarctic climate. PARASO features five distinct models, each covering different Earth system subcomponents (ice sheet, atmosphere, land, sea ice, ocean). In this technical article, we describe how this tool has been developed, with a focus on the
coupling interfacesrepresenting the feedbacks between the distinct models used for contribution. PARASO is stable and ready to use but is still characterized by significant biases.
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Jourdain, N. C., Molines, J.-M., Le Sommer, J., Mathiot, P., Chanut, J., de Lavergne, C., and Madec, G.: Simulating or prescribing the influence of tides on the Amundsen Sea ice shelves, Ocean Model., 133, 44–55, https://doi.org/10.1016/j.ocemod.2018.11.001, 2019.
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Short summary
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.
Icebergs ground when they reach shallow topography such as Bear Ridge in the Amundsen Sea....
