Articles | Volume 22, issue 1
https://doi.org/10.5194/os-22-587-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/os-22-587-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
12 Feb 2026
Research article |
| 12 Feb 2026
| 12 Feb 2026
Characterising marine heatwaves in the Svalbard Archipelago and surrounding seas
Marianne Williams-Kerslake
CORRESPONDING AUTHOR
Nansen Environmental and Remote Sensing Center (NERSC), Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
University of Bergen Geophysical Institute, Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
Helene R. Langehaug
Nansen Environmental and Remote Sensing Center (NERSC), Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
University of Bergen Geophysical Institute, Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
Ragnheid Skogseth
University Centre in Svalbard (UNIS), Longyearbyen, Svalbard, Norway
Frank Nilsen
University of Bergen Geophysical Institute, Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
University Centre in Svalbard (UNIS), Longyearbyen, Svalbard, Norway
Annette Samuelsen
Nansen Environmental and Remote Sensing Center (NERSC), Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
Silvana Gonzalez
Institute of Marine Research (IMR), Bjerknes Centre for Climate Research, Nordnesgaten 50, 5005, Bergen, Norway
Noel Keenlyside
Nansen Environmental and Remote Sensing Center (NERSC), Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
University of Bergen Geophysical Institute, Bjerknes Centre for Climate Research, Jahnebakken 3, 5007, Bergen, Norway
Related authors
Silvana González, Solfrid Sætre Hjøllo, Randi B. Ingvaldsen, Helene R. Langehaug, Anne Britt Sandø, Frode Vikebø, and Marianne Williams-Kerslake
EGUsphere, https://doi.org/10.5194/egusphere-2026-5043, https://doi.org/10.5194/egusphere-2026-5043, 2026
This preprint is open for discussion and under review for Ocean Science (OS).
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Marine heatwaves around Norway have become more frequent, longer-lasting and more widespread since 1991. Southern and coastal waters had more events, while northern waters had fewer but longer ones. Recent years exposed almost the whole open water region, raising risks for fisheries, kelp, seabirds and marine food webs.
Silvana González, Solfrid Sætre Hjøllo, Randi B. Ingvaldsen, Helene R. Langehaug, Anne Britt Sandø, Frode Vikebø, and Marianne Williams-Kerslake
EGUsphere, https://doi.org/10.5194/egusphere-2026-5043, https://doi.org/10.5194/egusphere-2026-5043, 2026
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Marine heatwaves around Norway have become more frequent, longer-lasting and more widespread since 1991. Southern and coastal waters had more events, while northern waters had fewer but longer ones. Recent years exposed almost the whole open water region, raising risks for fisheries, kelp, seabirds and marine food webs.
Quentin Dalaiden, François Counillon, Lea Svendsen, Ingo Bethke, and Noel Keenlyside
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2026-433, https://doi.org/10.5194/essd-2026-433, 2026
Preprint under review for ESSD
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Instrumental observations only cover a small part of Earth’s climate history, making it difficult to understand long-term climate changes. We combined information from natural climate archives, such as tree rings, corals, and ice cores, with a climate model to reconstruct climate variability over the last 500 years. Our reconstruction displays a good performance when compared with observations, provide a physically consistent picture of how the atmosphere and ocean evolved together through time.
Silvana Gonzalez, Mari F. Jensen, Ingrid A. Johnsen, Randi Ingvaldsen, Jon Albretsen, Lars Asplin, Anne Sandvik, Vidar S. Lien, Solfrid Sætre Hjøllo, and Anne Britt Sandø
State Planet Discuss., https://doi.org/10.5194/sp-2026-2, https://doi.org/10.5194/sp-2026-2, 2026
Revised manuscript under review for SP
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Marine heatwaves occurrence is increasing, especially in northern oceans. In summer 2025, western/central Norway had the most intense event on record, with sea temperatures up to 22 °C. This event was shallow and developed quickly. It was mainly driven by unusual weather: strong solar radiation, weak winds, warm air, and persistent high pressure over Scandinavia. The occurrence of these rapid-forming events has important implications for predictability and adaptation.
Achref Othmani, Annette Samuelsen, Jiping Xie, Laurent Bertino, Fabio Mangini, and Roshin Pappukutty Raj
EGUsphere, https://doi.org/10.5194/egusphere-2026-1520, https://doi.org/10.5194/egusphere-2026-1520, 2026
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We developed a high-resolution (6–10 km) HYCOM-CICE configuration to better understand ocean and sea ice conditions in the Arctic and North Atlantic from 2009 to 2019. By comparing the model with available datasets, we found it reliably captures major patterns and seasonal changes. This can support forecasting, helping improve environmental monitoring and decision-making in regions sensitive to climate change.
Marilaure Grégoire, Gianpiero Cossarini, Corinne Derval, Elodie Gutknecht, Susan Kay, Julien Lamouroux, Helen Morrison, Coralie Perruche, Annette Samuelsen, Lena Spruch, Anna Teruzzi, Luc Vandenbulcke, Karina Von Schuckmann, and Tsuyoshi Wakamatsu
EGUsphere, https://doi.org/10.5194/egusphere-2026-813, https://doi.org/10.5194/egusphere-2026-813, 2026
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We review the advancements in our capabilities to predict the green ocean in the frame of the European Copernicus Marine Service since its start in 2015 and for the five European seas, the Arctic and Global oceans. The evolutions of the prediction systems, delivered products and computing resources requirements are reviewed. Recommendations for future developments are proposed based on a SWOT analysis of current CMEMS green ocean prediction systems and products.
Issufo Halo, Tarron Lamont, Michael Hart-Davis, Pierrick Penven, Isabelle Ansorge, Chris Reason, Bjorn Backeberg, Siren Rühs, Erik van Sebille, Christo Whittle, Annette Samuelsen, Johnny Johannessen, Tamaryn Morris, Marjolaine Krug, Juliet Hermes, Marek Ostrowski, Sheveenah Taukoor, and Babatunde Abiodun
EGUsphere, https://doi.org/10.5194/egusphere-2025-6573, https://doi.org/10.5194/egusphere-2025-6573, 2026
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This review synthesizes two decades of research on the Greater Agulhas Current System, a major ocean current influencing climate, weather and marine life around southern Africa and beyond. Using improved observations, satellites, and computer models, we show how this system transports properties between oceans, affects rainfall and climate patterns, and marine ecosystems. The findings highlight its global climate importance and the need for sustained monitoring to better predict future change.
Hans Segura, Xabier Pedruzo-Bagazgoitia, Philipp Weiss, Sebastian K. Müller, Thomas Rackow, Junhong Lee, Edgar Dolores-Tesillos, Imme Benedict, Matthias Aengenheyster, Razvan Aguridan, Gabriele Arduini, Alexander J. Baker, Jiawei Bao, Swantje Bastin, Eulàlia Baulenas, Tobias Becker, Sebastian Beyer, Hendryk Bockelmann, Nils Brüggemann, Lukas Brunner, Suvarchal K. Cheedela, Sushant Das, Jasper Denissen, Ian Dragaud, Piotr Dziekan, Madeleine Ekblom, Jan Frederik Engels, Monika Esch, Richard Forbes, Claudia Frauen, Lilli Freischem, Diego García-Maroto, Philipp Geier, Paul Gierz, Álvaro González-Cervera, Katherine Grayson, Matthew Griffith, Oliver Gutjahr, Helmuth Haak, Ioan Hadade, Kerstin Haslehner, Shabeh ul Hasson, Jan Hegewald, Lukas Kluft, Aleksei Koldunov, Nikolay Koldunov, Tobias Kölling, Shunya Koseki, Sergey Kosukhin, Josh Kousal, Peter Kuma, Arjun U. Kumar, Rumeng Li, Nicolas Maury, Maximilian Meindl, Sebastian Milinski, Kristian Mogensen, Bimochan Niraula, Jakub Nowak, Divya Sri Praturi, Ulrike Proske, Dian Putrasahan, René Redler, David Santuy, Domokos Sármány, Reiner Schnur, Patrick Scholz, Dmitry Sidorenko, Dorian Spät, Birgit Sützl, Daisuke Takasuka, Adrian Tompkins, Alejandro Uribe, Mirco Valentini, Menno Veerman, Aiko Voigt, Sarah Warnau, Fabian Wachsmann, Marta Wacławczyk, Nils Wedi, Karl-Hermann Wieners, Jonathan Wille, Marius Winkler, Yuting Wu, Florian Ziemen, Janos Zimmermann, Frida A.-M. Bender, Dragana Bojovic, Sandrine Bony, Simona Bordoni, Patrice Brehmer, Marcus Dengler, Emanuel Dutra, Saliou Faye, Erich Fischer, Chiel van Heerwaarden, Cathy Hohenegger, Heikki Järvinen, Markus Jochum, Thomas Jung, Johann H. Jungclaus, Noel S. Keenlyside, Daniel Klocke, Heike Konow, Martina Klose, Szymon Malinowski, Olivia Martius, Thorsten Mauritsen, Juan Pedro Mellado, Theresa Mieslinger, Elsa Mohino, Hanna Pawłowska, Karsten Peters-von Gehlen, Abdoulaye Sarré, Pajam Sobhani, Philip Stier, Lauri Tuppi, Pier Luigi Vidale, Irina Sandu, and Bjorn Stevens
Geosci. Model Dev., 18, 7735–7761, https://doi.org/10.5194/gmd-18-7735-2025, https://doi.org/10.5194/gmd-18-7735-2025, 2025
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The Next Generation of Earth Modeling Systems project (nextGEMS) developed two Earth system models that use horizontal grid spacing of 10 km and finer, giving more fidelity to the representation of local phenomena, globally. In its fourth cycle, nextGEMS simulated the Earth System climate over the 2020–2049 period under the SSP3-7.0 scenario. Here, we provide an overview of nextGEMS, insights into the model development, and the realism of multi-decadal, kilometer-scale simulations.
Lukas Frank, Jon Albretsen, Ragnheid Skogseth, Frank Nilsen, and Marius O. Jonassen
Ocean Sci., 21, 2419–2442, https://doi.org/10.5194/os-21-2419-2025, https://doi.org/10.5194/os-21-2419-2025, 2025
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West of Svalbard, warm Atlantic Water frequently deviates from the West Spitsbergen Current onto shallow shelf areas, with significant implications for the regional climate system. The intrusions can be triggered by different processes, but their depths ultimately depend on the density difference between the intruding water and the ambient shelf water. These findings are an important step toward a better understanding of how warm Atlantic Water eventually reaches the fjords of Svalbard.
William E. Chapman, Francine Schevenhoven, Judith Berner, Noel Keenlyside, Ingo Bethke, Ping-Gin Chiu, Alok Gupta, and Jesse Nusbaumer
Geosci. Model Dev., 18, 5451–5465, https://doi.org/10.5194/gmd-18-5451-2025, https://doi.org/10.5194/gmd-18-5451-2025, 2025
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We introduce the first state-of-the-art atmosphere-connected supermodel, where two advanced atmospheric models share information in real time to form a new dynamical system. By synchronizing the models, particularly in storm track regions, we achieve better predictions without losing variability. This approach maintains key climate patterns and reduces bias in some variables compared to traditional models, demonstrating a useful technique for improving atmospheric simulations.
Yiguo Wang, François Counillon, Lea Svendsen, Ping-Gin Chiu, Noel Keenlyside, Patrick Laloyaux, Mariko Koseki, and Eric de Boisseson
Earth Syst. Sci. Data, 17, 4185–4211, https://doi.org/10.5194/essd-17-4185-2025, https://doi.org/10.5194/essd-17-4185-2025, 2025
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CoRea1860+ is a new climate dataset that reconstructs past climate conditions from 1860 to today. By using advanced modelling techniques and incorporating sea surface temperature observations, it provides a consistent picture of long-term climate variability. The dataset captures key ocean, sea ice, and atmosphere changes, helping scientists understand past climate changes and variability.
Ingo Richter, Ping Chang, Ping-Gin Chiu, Gokhan Danabasoglu, Takeshi Doi, Dietmar Dommenget, Guillaume Gastineau, Zoe E. Gillett, Aixue Hu, Takahito Kataoka, Noel S. Keenlyside, Fred Kucharski, Yuko M. Okumura, Wonsun Park, Malte F. Stuecker, Andréa S. Taschetto, Chunzai Wang, Stephen G. Yeager, and Sang-Wook Yeh
Geosci. Model Dev., 18, 2587–2608, https://doi.org/10.5194/gmd-18-2587-2025, https://doi.org/10.5194/gmd-18-2587-2025, 2025
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Tropical ocean basins influence each other through multiple pathways and mechanisms, referred to here as tropical basin interaction (TBI). Many researchers have examined TBI using comprehensive climate models but have obtained conflicting results. This may be partly due to differences in experiment protocols and partly due to systematic model errors. The Tropical Basin Interaction Model Intercomparison Project (TBIMIP) aims to address this problem by designing a set of TBI experiments that will be performed by multiple models.
Shunya Koseki, Lander R. Crespo, Jerry Tjiputra, Filippa Fransner, Noel S. Keenlyside, and David Rivas
Biogeosciences, 21, 4149–4168, https://doi.org/10.5194/bg-21-4149-2024, https://doi.org/10.5194/bg-21-4149-2024, 2024
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We investigated how the physical biases of an Earth system model influence the marine biogeochemical processes in the tropical Atlantic. With four different configurations of the model, we have shown that the versions with better SST reproduction tend to better represent the primary production and air–sea CO2 flux in terms of climatology, seasonal cycle, and response to climate variability.
Kjersti Kalhagen, Ragnheid Skogseth, Till M. Baumann, Eva Falck, and Ilker Fer
Ocean Sci., 20, 981–1001, https://doi.org/10.5194/os-20-981-2024, https://doi.org/10.5194/os-20-981-2024, 2024
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Atlantic water (AW) is a key driver of change in the Barents Sea. We studied an emerging pathway through the Svalbard Archipelago that allows AW to enter the Barents Sea. We found that the Atlantic sector near the study site has warmed over the past 2 decades; that Atlantic-origin waters intermittently enter the Barents Sea through the aforementioned pathway; and that heat transport is driven by tides, wind events, and variations in the upstream current system.
Akhilesh Sivaraman Nair, François Counillon, and Noel Keenlyside
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2023-217, https://doi.org/10.5194/gmd-2023-217, 2024
Publication in GMD not foreseen
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This study demonstrates the importance of soil moisture (SM) in subseasonal-to-seasonal predictions. To addess this, we introduce the Norwegian Climate Prediction Model Land (NorCPM-Land), a land data assimilation system developed for the NorCPM. NorCPM-Land reduces error in SM by 10.5 % by assimilating satellite SM products. Enhanced land initialisation improves predictions up to a 3.5-month lead time for SM and a 1.5-month lead time for temperature and precipitation.
Lina Boljka, Nour-Eddine Omrani, and Noel S. Keenlyside
Weather Clim. Dynam., 4, 1087–1109, https://doi.org/10.5194/wcd-4-1087-2023, https://doi.org/10.5194/wcd-4-1087-2023, 2023
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This study examines quasi-periodic variability in the tropical Pacific on interannual timescales and related physics using a recently developed time series analysis tool. We find that wind stress in the west Pacific and recharge–discharge of ocean heat content are likely related to each other on ~1.5–4.5-year timescales (but not on others) and dominate variability in sea surface temperatures on those timescales. This may have further implications for climate models and long-term prediction.
Veli Çağlar Yumruktepe, Erik Askov Mousing, Jerry Tjiputra, and Annette Samuelsen
Geosci. Model Dev., 16, 6875–6897, https://doi.org/10.5194/gmd-16-6875-2023, https://doi.org/10.5194/gmd-16-6875-2023, 2023
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We present an along BGC-Argo track 1D modelling framework. The model physics is constrained by the BGC-Argo temperature and salinity profiles to reduce the uncertainties related to mixed layer dynamics, allowing the evaluation of the biogeochemical formulation and parameterization. We objectively analyse the model with BGC-Argo and satellite data and improve the model biogeochemical dynamics. We present the framework, example cases and routines for model improvement and implementations.
Bjørg Risebrobakken, Mari F. Jensen, Helene R. Langehaug, Tor Eldevik, Anne Britt Sandø, Camille Li, Andreas Born, Erin Louise McClymont, Ulrich Salzmann, and Stijn De Schepper
Clim. Past, 19, 1101–1123, https://doi.org/10.5194/cp-19-1101-2023, https://doi.org/10.5194/cp-19-1101-2023, 2023
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In the observational period, spatially coherent sea surface temperatures characterize the northern North Atlantic at multidecadal timescales. We show that spatially non-coherent temperature patterns are seen both in further projections and a past warm climate period with a CO2 level comparable to the future low-emission scenario. Buoyancy forcing is shown to be important for northern North Atlantic temperature patterns.
Pedro Duarte, Jostein Brændshøi, Dmitry Shcherbin, Pauline Barras, Jon Albretsen, Yvonne Gusdal, Nicholas Szapiro, Andreas Martinsen, Annette Samuelsen, Keguang Wang, and Jens Boldingh Debernard
Geosci. Model Dev., 15, 4373–4392, https://doi.org/10.5194/gmd-15-4373-2022, https://doi.org/10.5194/gmd-15-4373-2022, 2022
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Sea ice models are often implemented for very large domains beyond the regions of sea ice formation, such as the whole Arctic or all of Antarctica. In this study, we implement changes in the Los Alamos Sea Ice Model, allowing it to be implemented for relatively small regions within the Arctic or Antarctica and yet considering the presence and influence of sea ice outside the represented areas. Such regional implementations are important when spatially detailed results are required.
Veli Çağlar Yumruktepe, Annette Samuelsen, and Ute Daewel
Geosci. Model Dev., 15, 3901–3921, https://doi.org/10.5194/gmd-15-3901-2022, https://doi.org/10.5194/gmd-15-3901-2022, 2022
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We describe the coupled bio-physical model ECOSMO II(CHL), which is used for regional configurations for the North Atlantic and the Arctic hind-casting and operational purposes. The model is consistent with the large-scale climatological nutrient settings and is capable of representing regional and seasonal changes, and model primary production agrees with previous measurements. For the users of this model, this paper provides the underlying science, model evaluation and its development.
Ingo Bethke, Yiguo Wang, François Counillon, Noel Keenlyside, Madlen Kimmritz, Filippa Fransner, Annette Samuelsen, Helene Langehaug, Lea Svendsen, Ping-Gin Chiu, Leilane Passos, Mats Bentsen, Chuncheng Guo, Alok Gupta, Jerry Tjiputra, Alf Kirkevåg, Dirk Olivié, Øyvind Seland, Julie Solsvik Vågane, Yuanchao Fan, and Tor Eldevik
Geosci. Model Dev., 14, 7073–7116, https://doi.org/10.5194/gmd-14-7073-2021, https://doi.org/10.5194/gmd-14-7073-2021, 2021
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The Norwegian Climate Prediction Model version 1 (NorCPM1) is a new research tool for performing climate reanalyses and seasonal-to-decadal climate predictions. It adds data assimilation capability to the Norwegian Earth System Model version 1 (NorESM1) and has contributed output to the Decadal Climate Prediction Project (DCPP) as part of the sixth Coupled Model Intercomparison Project (CMIP6). We describe the system and evaluate its baseline, reanalysis and prediction performance.
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Short summary
Marine heatwaves – periods of extreme ocean temperatures – are increasing globally, posing a threat to marine ecosystems. One region where a high number of marine heatwave events per year has been observed is around Svalbard. This study characterises past marine heatwave events in this region, including their extent in terms of both distance and depth. We identified eight events west of Svalbard that were largely driven by the movement of warmer water into the region by ocean currents.
Marine heatwaves – periods of extreme ocean temperatures – are increasing globally, posing a...
