Holtanová et al. (2025) Scenarios of Köppen-Trewartha climate types in Europe based on GCM-RCM combined projections

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-10-18
• Authors: Eva Holtanová, Michal Belda, Herijaona Hani‐Roge Hundilida Randriatsara, Amanda Imola Szabó, Tomáš Halenka
• DOI: 10.1007/s00704-025-05806-3

Research Groups

• Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

Short Summary

This study assesses projected changes in Köppen-Trewartha climate types across Europe throughout the 21st century using a novel hybrid method that combines global and regional climate model outputs. It finds a significant northward and eastward shift of climate zones, with colder types shrinking and warmer, drier types expanding, particularly in southern Europe, providing an updated CMIP6-based assessment.

Objective

• To assess projected changes in the distribution of Köppen-Trewartha climate types over Europe throughout the 21st century under two socio-economic scenarios.
• To investigate the boundary shifts between Europe’s most common climate types (temperate D and boreal E).
• To evaluate the utility of a hybrid method combining Global Climate Model (GCM) and Regional Climate Model (RCM) outputs for climate change assessment, incorporating the full GCM ensemble.

Study Configuration

• Spatial Scale: Europe, with data remapped to a 0.1° latitude/longitude horizontal resolution (approximately 11 km at mid-latitudes) for observational data and 110 meters (0.11 km) for RCM simulations.
• Temporal Scale: Reference period 1971–2000, and six 30-year future periods: 2016–2045, 2026–2055, 2036–2065, 2046–2075, 2056–2085, and 2066–2095.

Methodology and Data

• Models used:
  • Köppen-Trewartha Classification (KTC) scheme.
  • Hybrid method (Ruosteenoja and Räisänen, 2024) to combine GCM and RCM outputs, using multiplicative form for temperature changes and summation form for precipitation changes.
  • Delta approach (change-factor method) for bias adjustment of temperature and precipitation projections.
• Data sources:
  • Observational data: E-OBS dataset version 30.0e (0.1° horizontal resolution).
  • Global Climate Models (GCMs): Multi-model ensembles from CMIP5 and CMIP6.
  • Regional Climate Models (RCMs): Multi-model ensemble from EURO-CORDEX (0.11 km horizontal resolution).
  • Socio-economic scenarios: Representative Concentration Pathways (RCP4.5, RCP8.5) for CMIP5/EURO-CORDEX and Shared Socioeconomic Pathways (SSP2-4.5, SSP5-8.5) for CMIP6.

Main Results

• Colder climate types (tundra Ft, continental boreal Ec, oceanic boreal Eo, continental temperate Dc) are projected to shrink and shift northward and/or eastward across Europe.
• Warmer and drier climate types (oceanic temperate Do, humid subtropical Cf, steppe BS, Mediterranean Cs) are expected to expand.
• The continental boreal Ec type and tundra Ft type are projected to shrink radically, with Ec practically disappearing by the end of the 21st century under SSP2-4.5 and by mid-century under SSP5-8.5.
• Oceanic boreal Eo is projected to shrink from 12% (2016–2045) to 3% (SSP5-8.5) or 9% (SSP2-4.5) of the European domain by the end of the century (hybrid-CMIP6).
• The oceanic temperate Do type is projected for the largest expansion, migrating east and north into areas previously covered by Dc and Ec.
• Steppe (BS) and Mediterranean (Cs) climate types are projected to expand significantly in southern and southeastern Europe, with BS area expected to double under SSP2-4.5 and triple under SSP5-8.5.
• The desert (BW) climate type is projected to emerge in a small part of southern Spain (approximately 1% of the studied domain) under the higher-emission scenario.
• Climate type boundaries are projected to shift: the Dc/Eo boundary moves northward, and the Do/Dc boundary shows an eastward shift in the second half of the century under higher-emission scenarios.
• The hybrid-CMIP6 dataset generally projects the most pronounced changes, particularly over northern Europe, and a larger increase in dry climate types, reflecting faster temperature changes.

Contributions

• Provides the first assessment of updated CMIP6-based projections of Köppen-Trewartha climate types over Europe using a hybrid GCM-RCM method, anticipating the availability of new EURO-CORDEX simulations dynamically downscaling CMIP6.
• Introduces an innovative and computationally efficient hybrid method that integrates fine-scale RCM information with the climate change signal from the entire GCM ensemble, addressing uncertainties related to the limited number of driving GCMs in RCM ensembles.
• Offers new insights into projected regional changes of KTC climate types, emphasizing uncertainties related to the choice of underlying simulated data (CMIP5 vs. CMIP6, hybrid vs. raw RCMs).
• Generates results directly applicable as a basis for adaptation strategies and planning, and for identifying regions expected to undergo the most dramatic climate changes with implications for vegetation.

Funding

• Johannes Amos Comenius Programme (OP JAC) project No. CZ.02.01.01/00/22_008/0004605, Natural and anthropogenic georisk.

Citation

@article{Holtanová2025Scenarios,
  author = {Holtanová, Eva and Belda, Michal and Randriatsara, Herijaona Hani‐Roge Hundilida and Szabó, Amanda Imola and Halenka, Tomáš},
  title = {Scenarios of Köppen-Trewartha climate types in Europe based on GCM-RCM combined projections},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05806-3},
  url = {https://doi.org/10.1007/s00704-025-05806-3}
}