Zhang et al. (2025) Increases in global hot droughts across multiple timescales

Identification

• Journal: Science China Earth Sciences
• Year: 2025
• Date: 2025-09-24
• Authors: Yitong Zhang, Zengchao Hao, Yang Chen, Yuting Pang, Vijay P. Singh
• DOI: 10.1007/s11430-024-1680-4

Research Groups

• College of Water Sciences, Beijing Normal University, Beijing, China
• State Key Laboratory of Severe Weather Meteorological Science and Technology, Chinese Academy of Meteorological Sciences, Beijing, China
• Department of Biological and Agricultural Engineering and Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX, USA

Short Summary

This study comprehensively investigated global hot drought changes across weekly to annual timescales, revealing significant historical increases in frequency and spatial extent attributed to anthropogenic influences, with further exacerbation projected under future climate scenarios.

Objective

• To investigate changes in global hot droughts at multiple timescales in historical periods (1951–2014) and future climates (2015–2100).

Study Configuration

• Spatial Scale: Global, with analysis for 26 selected climate regions.
• Temporal Scale: Multiple timescales: weekly, monthly, seasonal, and annual. Historical period: 1951–2014. Future period: 2015–2100.

Methodology and Data

• Models used: Simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) for future climate projections under the Shared Socioeconomic Pathway (SSP) 2–4.5 scenario.
• Data sources: ECMWF Reanalysis v5 (ERA5) for historical periods. CMIP6 simulations for future periods.

Main Results

• In historical periods (1951–2014), a significant increase in the frequency of hot droughts was observed: 31.73% for weekly, 65.15% for monthly, 92.27% for seasonal, and 184.63% for annual scales.
• A consistent increase in the spatial extent of hot droughts was found for the four timescales in historical periods, with trends of 1.16%/decade (weekly), 1.84%/decade (monthly), 2.26%/decade (seasonal), and 3.38%/decade (annual).
• These increases in hot drought frequency and spatial extent are attributed to anthropogenic influences.
• During the historical period, Eastern Africa (EAF), Eastern Asia (EAS), Southern Europe/the Mediterranean (MED), Sahara (SAH), Southeast Asia (SEA), and Western Africa (WAF) showed higher increases in frequency or spatial extent across multiple timescales.
• Under the SSP2-4.5 scenario, increased frequency and spatial extents of hot droughts are projected for the future period (2015–2100), with prominent increases in Amazon (AMZ), MED, Northeast Brazil (NEB), Southern Africa (SAF), Southern Australia/New Zealand (SAU), and West Coast South America (WSA) across multiple timescales.

Contributions

• Provides a comprehensive understanding of global hot drought variability and changes across an unprecedented range of timescales (weekly to annual), addressing a gap in previous research.
• Combines analysis of historical trends using high-resolution reanalysis data (ERA5) with future projections from state-of-the-art climate models (CMIP6).
• Quantifies the increases in both frequency and spatial extent of hot droughts across different timescales and attributes these changes to anthropogenic influences.
• Identifies specific global climate regions that are particularly vulnerable to increasing hot drought frequency and extent in both historical and future contexts, offering valuable insights for adaptation strategies.

Funding

• National Natural Science Foundation of China (Grant No. 42271024)

Citation

@article{Zhang2025Increases,
  author = {Zhang, Yitong and Hao, Zengchao and Chen, Yang and Pang, Yuting and Singh, Vijay P.},
  title = {Increases in global hot droughts across multiple timescales},
  journal = {Science China Earth Sciences},
  year = {2025},
  doi = {10.1007/s11430-024-1680-4},
  url = {https://doi.org/10.1007/s11430-024-1680-4}
}