Sutanto et al. (2025) Future intensification of compound and consecutive drought and heatwave risks in Europe

Identification

• Journal: Natural hazards and earth system sciences
• Year: 2025
• Date: 2025-10-09
• Authors: Samuel Jonson Sutanto, Confidence Duku, Merve Gülveren, Rutger Dankers, Spyridon Paparrizos
• DOI: 10.5194/nhess-25-3879-2025

Research Groups

• Earth Systems and Global Change Group, Environmental Sciences Department, Wageningen University and Research, Wageningen, the Netherlands
• Climate Resilience Group, Wageningen Environmental Research, Wageningen, the Netherlands
• Directorate of Climate Change, Ministry of Environment, Urbanization, and Climate Change, Ankara, Turkiye

Short Summary

This study projects the future intensification of single and compound/consecutive drought and heatwave events across Europe and their impacts in Germany under climate change scenarios, finding significant increases in event characteristics and impacts across multiple regions.

Objective

• To identify the future characteristics (number, duration, frequency) of single, compound, and consecutive drought and heatwave hazards across Europe under SSP1-2.6 and SSP5-8.5 scenarios.
• To project the impacts of droughts and heatwaves on economic, non-economic, ecosystem, and human health sectors in Germany using a machine learning approach.

Study Configuration

• Spatial Scale: Pan-European analysis; Germany as a case study for impact projections. Data at 0.1° × 0.1° spatial resolution.
• Temporal Scale: Historical period: January 1953 to December 2014 (62 years). Future period: January 2039 to December 2100 (62 years). Heatwave analysis focused on the extended summer period (May to October).

Methodology and Data

• Models used:
  • Hydrological model: CWatM (within ISIMIP3b)
  • Climate models: Five CMIP6 global climate models (GFDL-ESM4, IPSL-CM6A-LR, MPI-ESM1-2-HR, MRI-ESM2-0, UKESM1-0-LL)
  • Drought identification: Standardized Soil Moisture Index (SMI)
  • Heatwave detection: Variable Threshold Method (VTM) using 90th percentile of daily maximum and minimum temperature thresholds.
  • Impact prediction: Extreme Gradient Boosting (XGBoost) machine learning approach.
  • Data preprocessing: Delta method for bias correction, bilinear interpolation for spatial resampling, Synthetic Minority Over-sampling Technique (SMOTE) for class imbalance.
• Data sources:
  • Soil moisture data: ERA5-Land (Copernicus Data Store), ISIMIP3b outputs.
  • Near-surface temperature data: ISIMIP hourly data (CMIP6 GCMs).
  • Drought and heatwave impact databases: European Drought Impact Inventory (EDII), international disaster database (EM-DAT), and data mined from scientific and grey literature.
  • Climate scenarios: Shared Socioeconomic Pathways (SSP1-2.6 and SSP5-8.5).

Main Results

• The number, duration, and frequency of single drought and heatwave events, as well as compound and consecutive (CnC) events, are projected to increase across Europe under both SSP1-2.6 and SSP5-8.5, with higher increases under SSP5-8.5.
• Under SSP5-8.5, drought events are projected to increase by at least 40 events compared to the reference period, with total durations exceeding 220 months in some regions. Average drought duration increases by up to 0.5 months, and frequency by 1 event per year.
• Drought hotspots are projected to expand from Western Europe towards Southern and Eastern Europe under SSP1-2.6, and across nearly all of Europe (except northern regions) under SSP5-8.5.
• Under SSP5-8.5, heatwave events are projected to increase by more than 350 events in 62 years in Southern Europe, with total durations increasing by over 4000 days (36%). Average heatwave duration increases by at least 6 days in Spain, Italy, and the Balkan region.
• Heatwave hotspots are projected to shift from Eastern Europe (historically) to the Mediterranean region (Spain, Italy, Balkan countries, southeastern Europe) in future scenarios.
• Compound Drought and Heatwave (CDH) events are projected to increase by 4 to 6 times compared to the reference period, while Consecutive Drought and Heatwave (CoDH) events are projected to rise by 3 to 3.5 times under SSP1-2.6 and SSP5-8.5, respectively.
• In Germany, drought impacts on economic, non-economic, and ecosystem sectors are projected to nearly double by 2100.
• Heatwave impacts on human health and mortality in Germany are projected to increase ninefold by 2100.
• Machine learning models showed robust performance for drought impact prediction (AUC values of 0.83 for economic, 0.76 for non-economic, and 0.81 for ecosystem sectors), though heatwave impact model performance (AUC=1) was influenced by limited data.

Contributions

• Provides a comprehensive analysis of future characteristics of both single and compound/consecutive drought and heatwave events across Europe, addressing a gap in literature that often focuses on single hazards.
• Pioneers the application of a hybrid machine learning approach to project multi-sectoral impacts of droughts and heatwaves, moving beyond hazard-centric predictions.
• Highlights the critical need for integrating compound and consecutive risk assessments into climate adaptation and disaster risk reduction strategies across Europe.
• Advocates for the establishment of a standardized, global multi-hazard impact database to facilitate improved impact-based forecasting and model development.

Funding

• CDHEU project, funded by the Wageningen Data Driven Discoveries in Changing Climate (D3-C2).

Citation

@article{Sutanto2025Future,
  author = {Sutanto, Samuel Jonson and Duku, Confidence and Gülveren, Merve and Dankers, Rutger and Paparrizos, Spyridon},
  title = {Future intensification of compound and consecutive drought and heatwave risks in Europe},
  journal = {Natural hazards and earth system sciences},
  year = {2025},
  doi = {10.5194/nhess-25-3879-2025},
  url = {https://doi.org/10.5194/nhess-25-3879-2025}
}