Peter Kuma
Science and Software

Article

nextGEMS: entering the era of kilometer-scale Earth system modeling Open access

Hans Segura1, Xabier Pedruzo-Bagazgoitia2, Philipp Weiss3, Sebastian K. Müller4, Thomas Rackow2, Junhong Lee1, Edgar Dolores-Tesillos5, Imme Benedict6, Matthias Aengenheyster2, Razvan Aguridan2, 7, … Gabriele Arduini2, Alexander J. Baker8, Jiawei Bao9, Swantje Bastin1, Eulàlia Baulenas7, Tobias Becker2, Sebastian Beyer10, Hendryk Bockelmann11, Nils Brüggemann1, Lukas Brunner12, Suvarchal K. Cheedela10, Sushant Das13, Jasper Denissen2, Ian Dragaud12, Piotr Dziekan14, Madeleine Ekblom15, Jan Frederik Engels11, Monika Esch1, Richard Forbes2, Claudia Frauen11, Lilli Freischem3, Diego García-Maroto16, Philipp Geier2, Paul Gierz10, Álvaro González-Cervera16, Katherine Grayson7, Matthew Griffith2, Oliver Gutjahr1, Helmuth Haak1, Ioan Hadade2, Kerstin Haslehner17, Shabeh ul Hasson18, Jan Hegewald19, Lukas Kluft1, Aleksei Koldunov10, Nikolay Koldunov10, Tobias Kölling1, Shunya Koseki20, Sergey Kosukhin1, Josh Kousal2, Peter Kuma21, Arjun U. Kumar1, Rumeng Li22, Nicolas Maury23, Maximilian Meindl17, Sebastian Milinski2, Kristian Mogensen2, Bimochan Niraula11, Jakub Nowak14, Divya Sri Praturi1, Ulrike Proske24, Dian Putrasahan1, René Redler1, David Santuy16, Domokos Sármány2, Reiner Schnur1, Patrick Scholz10, Dmitry Sidorenko10, Dorian Spät17, Birgit Sützl2, Daisuke Takasuka25, Adrian Tompkins26, Alejandro Uribe21, Mirco Valentini2, Menno Veerman6, Aiko Voigt17, Sarah Warnau6, 27, Fabian Wachsmann11, Marta Wacławczyk14, Nils Wedi2, Karl-Hermann Wieners1, Jonathan Wille28, Marius Winkler1, Yuting Wu1, Florian Ziemen11, Janos Zimmermann11, Frida A.-M. Bender21, Dragana Bojovic7, Sandrine Bony23, Simona Bordoni4, Patrice Brehmer29, Marcus Dengler30, Emanuel Dutra31, Saliou Faye32, Erich Fischer28, Chiel van Heerwaarden6, Cathy Hohenegger1, Heikki Järvinen15, Markus Jochum33, Thomas Jung10, Johann H. Jungclaus1, Noel S. Keenlyside20, Daniel Klocke1, Heike Konow1, Martina Klose22, Szymon Malinowski14, Olivia Martius5, Thorsten Mauritsen21, Juan Pedro Mellado12, Theresa Mieslinger1, Elsa Mohino16, Hanna Pawłowska14, Karsten Peters-von Gehlen11, Abdoulaye Sarré32, Pajam Sobhani34, Philip Stier3, Lauri Tuppi15, Pier Luigi Vidale8, Irina Sandu2, Bjorn Stevens1

1Max Planck Institute for Meteorology, Hamburg, Germany
2European Centre for Medium-Range Weather Forecasts, Bonn, Germany
3Department of Physics, University of Oxford, Oxford, United Kingdom
4University of Trento, Trento, Italy
5Institute of Geography, University of Bern, Bern, Switzerland
6Meteorology and Air Quality Group, Wageningen University, Wageningen, the Netherlands
7Barcelona Supercomputing Center, Barcelona, Spain
8National Centre for Atmospheric Science and Department of Meteorology, University of Reading, Reading, United Kingdom
9Institute of Science and Technology Austria, Klosterneuburg, Austria
10Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
11German Climate Computing Center, Hamburg, Germany
12Department of Earth System Sciences, University of Hamburg, Hamburg, Germany
13Department of Earth and Atmospheric Sciences, National Institute of Technology Rourkela, Rourkela, India
14Institute of Geophysics, Faculty of Physics, University of Warsaw, Warsaw, Poland
15Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
16Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Madrid, Spain
17Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria
18HAREME Lab, Earth and Society Research Hub (ESRAH), University of Hamburg, Hamburg, Germany
19Gauß-IT-Zentrum, Braunschweig University of Technology (GITZ), Braunschweig, Germany
20Geophysical Institute, University of Bergen, Bergen, Norway
21Department of Meteorology, Stockholm University, Stockholm, Sweden
22Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
23LMD/IPSL, CNRS, Université Pierre et Marie Curie, Paris, France
24Hydrology and Environmental Hydraulics Group, Wageningen University, Wageningen, the Netherlands
25Department of Geophysics, Tohoku University, Sendai, Japan
26Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
27Wetsus, European Centre of Excellence for Sustainable Water Technology, Leeuwarden, the Netherlands
28Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
29Institut de Recherche pour le Développement, Dakar, Senegal
30GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
31Instituto Português do Mar e da Atmosfera, Lisbon, Portugal
32Institut Sénégalais de Recherches Agricoles, Dakar, Senegal
33Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
34Latest Thinking GmbH, Hamburg, Germany

Abstract

The Next Generation of Earth Modeling Systems (nextGEMS) project aimed to produce multidecadal climate simulations, for the first time, with resolved kilometer-scale (km-scale) processes in the ocean, land, and atmosphere. In only 3 years, nextGEMS achieved this milestone with the two km-scale Earth system models, ICOsahedral Non-hydrostatic model (ICON) and Integrated Forecasting System coupled to the Finite-volumE Sea ice-Ocean Model (IFS-FESOM). nextGEMS was based on three cornerstones: (1) developing km-scale Earth system models with small errors in the energy and water balance, (2) performing km-scale climate simulations with a throughput greater than 1 simulated year per day, and (3) facilitating new workflows for an efficient analysis of the large simulations with common data structures and output variables. These cornerstones shaped the timeline of nextGEMS, divided into four cycles. Each cycle marked the release of a new configuration of ICON and IFS-FESOM, which were evaluated at hackathons. The hackathon participants included experts from climate science, software engineering, and high-performance computing as well as users from the energy and agricultural sectors. The continuous efforts over the four cycles allowed us to produce 30-year simulations with ICON and IFS-FESOM, spanning the period 2020–2049 under the SSP3-7.0 scenario. The throughput was about 500 simulated days per day on the Levante supercomputer of the German Climate Computing Center (DKRZ). The simulations employed a horizontal grid of about 5 km resolution in the ocean and 10 km resolution in the atmosphere and land. Aside from this technical achievement, the simulations allowed us to gain new insights into the realism of ICON and IFS-FESOM. Beyond its time frame, nextGEMS builds the foundation of the Climate Change Adaptation Digital Twin developed in the Destination Earth initiative and paves the way for future European research on climate change.

Journal:
Geoscientific Model Development
Volume:
18
Issue:
20
Pages:
7735–7761
DOI:
10.5194/gmd-18-7735-2025
Submitted:
3 February 2025
Accepted:
27 July 2025
Published:
23 October 2025
License:
Open access / Creative Commons Attribution 4.0 (CC BY 4.0)
Cite as:
Segura, H., Pedruzo-Bagazgoitia, X., Weiss, P., Müller, S. K., Rackow, T., Lee, J., Dolores-Tesillos, E., Benedict, I., Aengenheyster, M., Aguridan, R., Arduini, G., Baker, A. J., Bao, J., Bastin, S., Baulenas, E., Becker, T., Beyer, S., Bockelmann, H., Brüggemann, N., … Stevens, B. (2025). nextGEMS: entering the era of kilometer-scale Earth system modeling. Geoscientific Model Development, 18, 7735–7761. https://doi.org/10.5194/gmd-18-7735-2025
Segura, H. et al. (2025) “nextGEMS: entering the era of kilometer-scale Earth system modeling,” Geoscientific Model Development, 18, pp. 7735–7761. Available at: https://doi.org/10.5194/gmd-18-7735-2025.
Segura, Hans, Xabier Pedruzo-Bagazgoitia, Philipp Weiss, et al. “NextGEMS: Entering the Era of Kilometer-Scale Earth System Modeling.” Geoscientific Model Development 18 (October 2025): 7735–61. https://doi.org/10.5194/gmd-18-7735-2025.
Segura, H., Pedruzo-Bagazgoitia, X., Weiss, P., Müller, S. K., Rackow, T., Lee, J., et al. (2025). nextGEMS: entering the era of kilometer-scale Earth system modeling. Geoscientific Model Development, 18, 7735–7761. https://doi.org/10.5194/gmd-18-7735-2025
Segura, H., and Coauthors, 2025: nextGEMS: entering the era of kilometer-scale Earth system modeling. Geoscientific Model Development, 18, 7735–7761, https://doi.org/10.5194/gmd-18-7735-2025.
Segura, H., Pedruzo-Bagazgoitia, X., Weiss, P., Müller, S. K., Rackow, T., Lee, J., Dolores-Tesillos, E., Benedict, I., Aengenheyster, M., Aguridan, R., Arduini, G., Baker, A. J., Bao, J., Bastin, S., Baulenas, E., Becker, T., Beyer, S., Bockelmann, H., Brüggemann, N., Brunner, L., Cheedela, S. K., Das, S., Denissen, J., Dragaud, I., Dziekan, P., Ekblom, M., Engels, J. F., Esch, M., Forbes, R., Frauen, C., Freischem, L., García-Maroto, D., Geier, P., Gierz, P., González-Cervera, Á., Grayson, K., Griffith, M., Gutjahr, O., Haak, H., Hadade, I., Haslehner, K., ul Hasson, S., Hegewald, J., Kluft, L., Koldunov, A., Koldunov, N., Kölling, T., Koseki, S., Kosukhin, S., Kousal, J., Kuma, P., Kumar, A. U., Li, R., Maury, N., Meindl, M., Milinski, S., Mogensen, K., Niraula, B., Nowak, J., Praturi, D. S., Proske, U., Putrasahan, D., Redler, R., Santuy, D., Sármány, D., Schnur, R., Scholz, P., Sidorenko, D., Spät, D., Sützl, B., Takasuka, D., Tompkins, A., Uribe, A., Valentini, M., Veerman, M., Voigt, A., Warnau, S., Wachsmann, F., Wacławczyk, M., Wedi, N., Wieners, K.-H., Wille, J., Winkler, M., Wu, Y., Ziemen, F., Zimmermann, J., Bender, F. A.-M., Bojovic, D., Bony, S., Bordoni, S., Brehmer, P., Dengler, M., Dutra, E., Faye, S., Fischer, E., van Heerwaarden, C., Hohenegger, C., Järvinen, H., Jochum, M., et al.: nextGEMS: entering the era of kilometer-scale Earth system modeling, Geoscientific Model Development, 18, 7735–7761, https://doi.org/10.5194/gmd-18-7735-2025, 2025.

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