Geoscientific Model Development
Geoscientific Model Development
GMD
Articles | Volume 18, issue 20
Articles | Volume 18, issue 20
https://doi.org/10.5194/gmd-18-7735-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-18-7735-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Articles | Volume 18, issue 20
Development and technical paper
 | Highlight paper
 | 
23 Oct 2025
Development and technical paper | Highlight paper |  | 23 Oct 2025

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

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

Data sets

nextGEMS: output of the model development cycle 2 simulations for ICON and IFS K.-H. Wieners et al. https://doi.org/10.26050/WDCC/nextGEMS_cyc2

nextGEMS: output of the model development cycle 3 simulations for ICON and IFS, N. Koldunov et al. https://doi.org/10.26050/WDCC/nextGEMS_cyc3

nextGEMS: output of the production simulations for ICON and IFS K.-H. Wieners et al. https://doi.org/10.35095/WDCC/nextGEMS_prod_addinfov1

Namelist files and settings for 30-year km-scale nextGEMS Cycle 4 production simu- lations with IFS-FESOM T. Rackow et al. https://doi.org/10.5281/zenodo.14725225

Model code and software

ICON release 2024.01 ICON partnership (DWD, MPI-M, DKRZ, KIT, C2SM) https://doi.org/10.35089/WDCC/IconRelease01

FESOM2.5 source code used in nextGEMS Cycle 3 simulations with IFS-FESOM T. Rackow et al. https://doi.org/10.5281/zenodo.10225420

Source code changes to the Integrated Forecasting System (IFS) for nextGEMS simulations T. Rackow et al. https://doi.org/10.5281/zenodo.10223577

nextGEMS overview paper: scripts H. Segura et al. https://doi.org/10.17617/3.QZHXMC

Video abstract

nextGEMS: entering the era of kilometer-scale Earth system modeling H. Segura et al. https://doi.org/10.5446/71373

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Executive editor
Kilometre-scale global climate models are pivotal for delivering nuanced regional climate insights and informing climate action, though they face the formidable challenge of balancing computational demands with the precision required to simulate complex subgrid processes. This paper is one of the landmarks in climate modelling, demonstrating the potential of kilometre-scale models to enhance regional climate understanding. It overcomes computational hurdles to achieve high-resolution simulations, crucial for capturing mesoscale phenomena. The authors' transparent exploration of challenges and successes makes this a vital read for climate scientists, offering insights into the future of climate modelling and its applications in climate action.
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Short summary
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.
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