Beier et al. (2026) NUKLEUS—A First Convection-Permitting Multimodel Ensemble for Germany: Assessment of Future Changes in Temperature and Precipitation Extremes

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-10-14
• Authors: Christian Beier, Katrin Ziegler, Heiko Paeth, Joaquim Ginete Pinto, Kevin Sieck, Lars Buntemeyer, Beate Geyer, Elena Xoplaki, Edgar Espitia, Christoph Braun, Florian Ehmele, Hendrik Feldmann, Christopher Kadow, Katja Trachte
• DOI: 10.1175/jcli-d-25-0613.1

Research Groups

• Department of Atmospheric processes, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
• Working group Climatology, Institute of Geography and Geology, Universität of Wuerzburg, Wuerzburg, Germany
• Institute of Meteorology and Climate Research – Troposphere Research (IMKTRO), Karlsruhe Institute of Technology, Karlsruhe, Germany
• Climate Service Center Germany (GERICS), Helmholtz-Zentrum Hereon, Hamburg, Germany
• Institute of Coastal Systems - Analysis and Modeling, Helmholtz-Zentrum Hereon, Geesthacht, Germany
• CMCC Foundation - Euro-Mediterranean Center on Climate Change, Bologna, Italy
• Department of Geography, Justus Liebig University Giessen, Giessen, Germany
• Environmental Computing, Leibniz Supercomputing Centre (LRZ), Garching, Germany
• Deutsches Klimarechenzentrum (DKRZ), Hamburg, Germany

Short Summary

This study utilizes a novel nine-member convection-permitting regional climate ensemble (NUKLEUS) for Germany to project future changes in temperature and precipitation extremes under +2 K and +3 K global warming levels, revealing intensified nocturnal warming and a significant increase in the frequency and intensity of extreme precipitation events, particularly in summer.

Objective

• To assess projected changes in temperature and precipitation extremes over Germany under two future global warming levels (+2 K and +3 K) using a novel nine-member convection-permitting regional climate ensemble.
• To evaluate the robustness of the climate change signals within the ensemble to ensure the reliability of the results.

Study Configuration

• Spatial Scale: Germany, at convection-permitting (kilometer-scale) resolution.
• Temporal Scale: Projections for the twenty-first century, specifically under global warming levels of +2 K and +3 K.

Methodology and Data

• Models used: NUKLEUS, a nine-member convection-permitting regional climate model ensemble.
• Data sources: Outputs from the NUKLEUS convection-permitting regional climate simulations. Climate indices were derived from these simulations.

Main Results

• Temperature-related extremes are projected to intensify throughout the twenty-first century.
• Nighttime temperature extremes show larger increases than daytime extremes, indicating amplified nocturnal warming with elevated risks to human health and ecosystems.
• Annual precipitation sums in Germany are projected to change only slightly and are mostly not statistically significant.
• The frequency and intensity of intense and very extreme precipitation events increase substantially.
• This increase in extreme precipitation is particularly evident in summer, despite a predominantly decreasing seasonal mean rainfall, suggesting drier summers interrupted by heavy rainfall events.
• Temperature-related extremes exhibit high robustness across almost all of Germany.
• Precipitation-related extremes show greater variability, reflecting stronger natural variability and model uncertainty.
• The high-resolution simulations demonstrate added value for temperature-based indices, including more detailed spatial patterns of time averages and changes in specific areas, along with reduced uncertainty.

Contributions

• Presents the first convection-permitting multimodel ensemble (NUKLEUS) specifically for Germany, offering high-resolution climate change projections.
• Provides a robust scientific basis for developing adaptation strategies tailored to small-scale landscape units.
• Highlights the added value of high-resolution simulations for temperature extremes, showing more detailed spatial patterns and reduced uncertainty.
• Identifies a critical contrasting change in summer precipitation, with overall drier conditions but a significant increase in intense rainfall events, impacting both drought and flood risk.

Funding

Not specified in the provided text.

Citation

@article{Beier2026NUKLEUSA,
  author = {Beier, Christian and Ziegler, Katrin and Paeth, Heiko and Pinto, Joaquim Ginete and Sieck, Kevin and Buntemeyer, Lars and Geyer, Beate and Xoplaki, Elena and Espitia, Edgar and Braun, Christoph and Ehmele, Florian and Feldmann, Hendrik and Kadow, Christopher and Trachte, Katja},
  title = {NUKLEUS—A First Convection-Permitting Multimodel Ensemble for Germany: Assessment of Future Changes in Temperature and Precipitation Extremes},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-25-0613.1},
  url = {https://doi.org/10.1175/jcli-d-25-0613.1}
}