In the first phase of the nextGEMS project, the two Earth-system models ICON (Version ee0ee6) and IFS (Cycle 48r1 nextGEMS) are developed in three iterative cycles aiming at simulating the climate 30 years into the future at storm-resolving scale. In each development cycle new features are implemented into the models improving the physical representation of the coupled Earth system as well as the technical feasibility to run at high resolution for increasing simulation time periods. A development cycle concludes with a simulation for at least one year at 5 km horizontal resolution or lower. A subset of the Cycle 3 data is published here, namely monthly averages of selected 2d variables from the 5km ICON simulation and 4km IFS simulation. When using the data, please always cite Hohenegger et al., 2023 (for ICON data) and Rackow et al., 2024 (for IFS-FESOM data).

In the first phase of the nextGEMS project, the two Earth-system models ICON (Version ee0ee6) and IFS (Cycle 47r3.3 nextGEMS) are developed in three iterative cycles aiming at simulating the climate 30 years into the future at storm-resolving scale. In each development cycle new features are implemented into the models improving the physical representation of the coupled Earth system as well as the technical feasibility to run at high resolution for increasing simulation time periods. A development cycle concludeds with a simulation for at least one year at 5 km horizontal resolution or lower. The cycle 2 model runs produced about 1 PB of model output. A subset of the data is published here, namely monthly averages of selected 2d variables from the 5km ICON simulation and 4km IFS simulation.

ETCCDI indices calculated from two km-scale global models developed within the nextGEMS project (https://nextgems-h2020.eu/): ICON-Sapphire (Hohenegger et al. 2023) and IFS-FESOM (Rackow et al. 2025). The indices are based on the 30-year production simulations of nextGEMS, cycle 4 with a spatial resolution of about 10km (Segura et al. 2025). Here, we provide them in the 29-year period 2021-2049 (as the first year, 2020, is incomplete for IFS), driven by the high-emission pathway SSP3-7.0. The original data and the derived indices are available on the unstructured HEALPix grid (Górski et al. 2005). HEALPix organises data at discrete resolutions or zoom levels. Here, the highest resolved zoom level 9 (about 13km grid spacing corresponding to about 3 million grid cells globally) and the intermediate (“CMIP6-like”) zoom level 6 (about 102km, 50’000 grid cells) are provided. The data were processed by Lukas Brunner (https://orcid.org/0000-0001-5760-4524), using a Climate Data Operators (https://code.mpimet.mpg.de/projects/cdo/embedded/index.html) implementation of the ETCCID indices: code on GitHub (https://doi.org/10.5281/zenodo.15582463). Time-mean plots of all indices are available on Zenodo: https://doi.org/10.5281/zenodo.15613611 If you use the indices, please cite this dataset and the accompanying publication: Brunner L., B. Poschlod, E. Dutra, E. M. Fischer, O. Martius, and J. Sillmann (2025): A global perspective on the spatial representation of climate extremes from km-scale models. Environmental Research Letters, https://doi.org/10.1088/1748-9326/ade1ef