Ghazi et al. (2025) Drought characteristics in the Middle East simulated by raw and bias-corrected CMIP6 models

Identification

• Journal: The Science of The Total Environment
• Year: 2025
• Date: 2025-09-22
• Authors: Babak Ghazi, Hossein Salehi, Kaveh Madani, Hossein Tabari
• DOI: 10.1016/j.scitotenv.2025.180468

Research Groups

• Department of Meteorology and Climatology, Faculty of Earth Sciences and Spatial Management, Nicolaus Copernicus University, Toruń, Poland
• University of Trento, Department of Physics, Center Agriculture, Food and Environment (C3A), Italy
• United Nations University Institute for Water, Environment and Health (UNU-INWEH), Richmond Hill, Ontario, Canada
• M4S, Faculty of Applied Engineering, University of Antwerp, Antwerp, Belgium
• Department of Meteorological and Climate Research, Royal Meteorological Institute of Belgium, Brussels, Belgium

Short Summary

This study compares raw and bias-corrected CMIP6 GCMs (NEX-GDDP) to project future drought characteristics in the Middle East under various SSP scenarios, finding a significant increase in drought probability, particularly when considering the increasing role of warming-driven evapotranspiration.

Objective

• To provide comprehensive comparisons of NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) and raw general circulation models (GCMs) from Coupled Model Intercomparison Project Phase 6 (CMIP6) to understand how model biases and spatial resolution influence future drought projections in the Middle East.

Study Configuration

• Spatial Scale: Middle East
• Temporal Scale: Historical (1985–2014), near future (2041–2070), and far future (2071–2100) periods.

Methodology and Data

• Models used: Coupled Model Intercomparison Project Phase 6 (CMIP6) General Circulation Models (GCMs) (raw and NEX-GDDP), Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI).
• Data sources: CMIP6 GCM outputs, NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP).

Main Results

• Drought probability is projected to significantly increase in the Middle East for both raw-GCMs and NEX-GDDP models.
• SPEI consistently projects a higher probability and broader spatial extent of droughts in the far future compared to SPI, particularly for longer durations (6- and 12-month scales), highlighting the increasing role of warming-driven evapotranspiration.
• Under SSP3–7.0 and SSP5–8.5 scenarios in the far future, SPEI-based mean drought probability is projected to increase by 33 %–41 %, compared to 6 %–15 % for SPI-based drought.
• NEX-GDDP models outperform raw-GCMs in projecting droughts in the Middle East.

Contributions

• Provides a comprehensive comparison of raw and bias-corrected (NEX-GDDP) CMIP6 GCMs for drought projections in the Middle East, addressing the critical gap in understanding the influence of model biases and spatial resolution.
• Quantifies the differential impact of precipitation-only (SPI) versus precipitation-evapotranspiration (SPEI) indices on future drought projections, emphasizing the increasing role of warming-driven evapotranspiration.

Funding

• [No explicit funding information provided in the paper text.]

Citation

@article{Ghazi2025Drought,
  author = {Ghazi, Babak and Salehi, Hossein and Madani, Kaveh and Tabari, Hossein},
  title = {Drought characteristics in the Middle East simulated by raw and bias-corrected CMIP6 models},
  journal = {The Science of The Total Environment},
  year = {2025},
  doi = {10.1016/j.scitotenv.2025.180468},
  url = {https://doi.org/10.1016/j.scitotenv.2025.180468}
}