Mathbout et al. (2025) Europe’s Double Threat: Evolving patterns of compound heatwaves and droughts

Identification

• Journal: International Journal of Applied Earth Observation and Geoinformation
• Year: 2025
• Date: 2025-11-25
• Authors: Shifa Mathbout, George Boustras, Joan Albert Lopez Bustins, Javier Martin Vide, Pierantonios Papazoglou
• DOI: 10.1016/j.jag.2025.104987

Research Groups

• Center of Excellence in Risk & Decision Sciences (CERIDES), European University, Nicosia, Cyprus
• Climatology Group, University of Barcelona, Department of Geography, 08001 Barcelona, Spain

Short Summary

This study quantifies the spatiotemporal evolution of Compound Hot and Dry Events (CHDEs) across Europe from 1980 to 2023, revealing a significant post-2000 intensification and northward/eastward expansion, primarily driven by heatwaves, with urban areas showing disproportionately higher increases.

Objective

• To quantify the spatiotemporal evolution, frequency, duration, and severity of Compound Hot and Dry Events (CHDEs) across Europe from 1980 to 2023.
• To identify persistent and emerging hotspots of CHDEs.
• To decompose the relative contributions of heatwaves (HWs) and dry events (DEs) to CHDE intensification.
• To assess urban-rural contrasts in CHDE trends across Europe.

Study Configuration

• Spatial Scale: Europe (25° N–71.5° N, 25° W–45° E) at 0.1° × 0.1° spatial resolution.
• Temporal Scale: 1980–2023, focusing on the warm season (May–September) using daily data. Analysis periods were also split into 1980–2001 and 2002–2023, and aggregated by decade.

Methodology and Data

• Models used:
  • Compound-event detection framework combining percentile-based Heatwave (HW) thresholds (85th, 90th, 95th percentiles of daily maximum temperature) with Effective Drought Index (EDI) metrics.
  • HWs defined as 3, 5, or 7 consecutive days exceeding temperature thresholds.
  • Droughts defined as EDI < -1.0.
  • Modified Mann–Kendall Test (MMKT) and Sen’s slope estimator for trend analysis.
  • Cumulative Sum (CUSUM) charts for detecting regime shifts.
  • Non-parametric two-sample tests (Mann–Whitney U, Cram´er–von Mises, Kolmogorov–Smirnov) for distributional shifts.
  • Change Vector Analysis (CVA) to assess relative contributions of HWs and DEs.
  • Urban classification based on geodesic distance (within 25 km) to 51 European national capitals using the Haversine formula.
• Data sources:
  • E-OBS v30.0e dataset (released September 2024), a high-resolution (0.1° × 0.1°) gridded product of daily maximum temperature and precipitation data for Europe.
  • E-OBS integrates in-situ data from National Meteorological and Hydrological Services (NMHSs), European Climate Assessment & Dataset (ECA&D), and regional networks.

Main Results

• Annual CHDEs increased by 35–45% after 2000, with severe 7-day events (95th percentile) rising by 2.7% per year.
• The Mediterranean basin (Iberia, southern France, Italy, Greece, western Turkey) remains the principal hotspot for CHDEs, exhibiting the highest frequencies and intensities.
• Central and northern Europe (Germany, Poland, the Baltic region, southern Scandinavia) experienced a three- to five-fold rise in CHDE frequency.
• Heatwaves (HWs) are the dominant driver of CHDE intensification across Europe (mean vector angle ≈12°), with dry events (DEs) amplifying risks regionally.
• Urban areas show 60–70% higher CHDE growth rates than rural zones, reflecting strong Urban Heat Island effects.
• A clear regime shift in CHDE occurrence was detected around 2000, with sustained increases across all thresholds post-2000.
• The Effective Drought Index (EDI) demonstrated high correlation with SPI-1 (r = 0.87), SPI-3 (r = 0.84), and SPI-9 (r = 0.77), confirming its reliability for both short- and long-term drought detection.

Contributions

• Provides the first high-resolution, continent-wide assessment of CHDEs in Europe from 1980 to 2023, revealing pronounced post-2000 intensification and geographic expansion.
• Identifies heatwaves as the dominant driver of recent CHDE increases, while quantifying regional drought contributions.
• Highlights disproportionately strong CHDE intensification in urban areas, emphasizing increased urban vulnerability.
• Establishes a scalable CHDE-detection framework integrating high-resolution daily data with a comprehensive compound-event analysis (frequency, severity, duration, and trend directionality).
• Informs integrated adaptation strategies for heat-drought resilience, including water-efficient technologies, climate-smart agriculture, and enhanced heat-health preparedness.
• Directly supports Sustainable Development Goals (SDGs) related to food and water security (SDGs 2 and 6), resilient cities (SDG 11), and climate action (SDG 13).

Funding

• “Horizon Europe – 2nd Opportunity” project (Protocol No: OPPTY-MSCA/1122/0050), funded by the Research and Innovation Foundation (RIF), Cyprus.
• Collaboration with the Climate Change and Landscape Ecology Group (2021 SGR 00310), funded by the Catalan Government.

Citation

@article{Mathbout2025Europes,
  author = {Mathbout, Shifa and Boustras, George and Bustins, Joan Albert Lopez and Vide, Javier Martin and Papazoglou, Pierantonios},
  title = {Europe’s Double Threat: Evolving patterns of compound heatwaves and droughts},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2025},
  doi = {10.1016/j.jag.2025.104987},
  url = {https://doi.org/10.1016/j.jag.2025.104987}
}

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