Pyarali et al. (2025) Assessment of Selected Climate Indicators Across the Elbe River Basin to Analyse Changes in Climate Extremes and their Effects

Identification

• Journal: Earth Systems and Environment
• Year: 2025
• Date: 2025-10-09
• Authors: Karim Pyarali, Lulu Zhang, Matthias Forkel
• DOI: 10.1007/s41748-025-00855-0

Research Groups

• Institute of Photogrammetry and Remote Sensing, Technische Universität Dresden, Germany
• United Nations University Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES), Germany

Short Summary

This study assesses the future impacts of climate change on extreme temperature, precipitation, and agrometeorological events across the Elbe River basin using high-resolution climate model ensembles under RCP2.6 and RCP8.5 scenarios, finding increased heatwaves, regional floods, and complex, often hindering, effects on agriculture by the end of the century.

Objective

• To assess the impacts of climate change on extreme temperature, precipitation, and agrometeorological events across the Elbe River basin at a regional scale.
• To identify vulnerable areas within the basin and analyze how changes in climate extremes will impact natural resources (e.g., agriculture, water, forests).
• To provide critical insights for policymakers to develop informed climate adaptation and mitigation strategies.

Study Configuration

• Spatial Scale: Elbe River basin (148,268 km²), delineated into 97 subbasins, using climate model data with a 12.5 km spatial resolution.
• Temporal Scale: Historical period (1970–1999), near-future (2020–2050), and far-future (2070–2098), covering a total period from 1970 to 2098.

Methodology and Data

• Models used:
  • Ensemble of projected climate model data from the European Coordinated Regional Downscaling Experiment (EURO-CORDEX).
  • Three Global Climate Models (GCMs): MOHC-HadGEM2-ES, NCC-NorESM1-M, MPI-M-MPI-ESM-LR.
  • Four Regional Climate Models (RCMs): HadREM3-GA7-05, RegCM4-6, RACMO22E, REMO2015.
  • Two Representative Concentration Pathway (RCP) scenarios: RCP2.6 (low emissions) and RCP8.5 (high emissions).
  • Statistical methods: Sen’s Slope method, Mann Kendall test, Hamed & Ramandra Rao’s variance correction, Hovmöller Diagram analysis, Seasonal analysis.
  • Software: RClimDex (v1.9-3) on R programming language (v4.2.3).
• Data sources:
  • Daily precipitation (Pr), maximum temperature (Tasmax), and minimum temperature (Tasmin) from EURO-CORDEX.
  • Eight climate extreme indices (mostly from ETCCDI):
    • Temperature-based: TXx (maximum daily maximum temperature), TNn (minimum daily minimum temperature), TR (tropical nights, minimum temperature > 20 °C).
    • Precipitation-based: Rx5day (maximum consecutive 5-day precipitation), R95pTOT (annual total precipitation on very wet days, >95th percentile), CDD (consecutive dry days, <1 mm precipitation).
    • Agrometeorological: GSL (growing season length), HS (heat sum during growing season).

Main Results

• Temperature-based extremes:
  • By the end of the century, temperature-based extremes will increase across the basin under both scenarios.
  • Under RCP2.6 (historical to far future): TXx increases by approximately 2 °C, TNn by approximately 3 °C, and TR by approximately 1 day.
  • Under RCP8.5 (historical to far future): TXx increases by approximately 7 °C, TNn by approximately 8 °C, and TR by more than 10 days.
  • Temperature-based extremes show minimal spatial variation for summer months, with the largest seasonal changes in TXx during summer and TNn during winter.
  • Heatwaves (TR) are projected to increase significantly in frequency, intensity, and distribution, particularly in the central and southeastern regions.
• Precipitation-based extremes:
  • Conditions promoting flood events are projected to increase, especially in the headwater regions located in the South of the basin.
  • Under RCP2.6 (historical to far future): Rx5day increases by approximately 3.5 mm, R95pTOT by approximately 30 mm, and CDD reduces by approximately 0.5 days.
  • Under RCP8.5 (historical to far future): Rx5day increases by approximately 9.5 mm, R95pTOT by approximately 68 mm, and CDD increases by approximately 0.5 days.
  • Consecutive dry days (CDD) show mostly statistically insignificant trends, making robust conclusions about drought conditions challenging with this index.
• Agrometeorological indicators:
  • Factors favorable for agricultural processes (GSL, HS) will become more common due to a longer growing season and additional heat units.
  • Under RCP2.6 (historical to far future): GSL increases by approximately 26 days, and HS by approximately 213 °Cd.
  • Under RCP8.5 (historical to far future): GSL increases by approximately 2 months, and HS by approximately 640 °Cd, with no signs of peaking by the end of the century.
  • However, the trend and seasonal analysis indicate that unreliable precipitation patterns will hinder the application of best farming practices.

Contributions

• This is the first basin-wide study for the Elbe River Basin to assess climate change impacts on extreme events using high-resolution regional-scale climate indices.
• Provides a comprehensive analysis of temperature, precipitation, and agrometeorological extremes at a subbasin scale (12.5 km resolution), enabling identification of climate-related patterns for specific areas like cities, national parks, and forests.
• Offers critical insights for policymakers on climate adaptation and mitigation, including specific policy recommendations such as green infrastructure, adaptive cropping calendars, and strengthened flood defenses.
• Highlights the complex impacts of a warming climate on natural resources and identifies vulnerable regions.
• Makes the developed climate indices datasets open-source for further research and collaboration.

Funding

• Projekt DEAL (Open Access funding)
• Klimakonform project, funded by Bundesministerium für Bildung und Forschung (bmbf) (Federal Ministry of Education and Research)

Citation

@article{Pyarali2025Assessment,
  author = {Pyarali, Karim and Zhang, Lulu and Forkel, Matthias},
  title = {Assessment of Selected Climate Indicators Across the Elbe River Basin to Analyse Changes in Climate Extremes and their Effects},
  journal = {Earth Systems and Environment},
  year = {2025},
  doi = {10.1007/s41748-025-00855-0},
  url = {https://doi.org/10.1007/s41748-025-00855-0}
}