Khosravi et al. (2026) Projected Spatial Asymmetry of Daytime and Nighttime Temperature Extremes in the Middle East under CMIP6 Warming

Identification

• Journal: Scientific Reports
• Year: 2026
• Date: 2026-09-07
• Authors: Younes Khosravi, Taha B. M. J. Ouarda
• DOI: 10.1038/s41598-026-68572-w

Research Groups

• Department of Geography, University of Tehran
• Climate Change Research Center, University of Melbourne
• Institute of Atmospheric Sciences, Iran Meteorological Organization

Short Summary

This study investigates projected asymmetry between daytime and nighttime temperature extremes across the Middle East using Stacking Ensemble Machine Learning (Stacking-EML)-refined CMIP6 projections. The analysis combines delta-based projections with Global Moran's I, Getis–Ord Gi* hotspot statistics, and two day–night asymmetry metrics to evaluate whether future warming is preferentially daytime- or nighttime-dominated across the region.

Objective

• Investigate projected changes in temperature extremes across the Middle East under different climate scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5)
• Evaluate the spatial organization of projected temperature-extreme changes using Global Moran's I and Getis–Ord Gi* hotspot analysis
• Develop day–night asymmetry metrics to quantify differences between projected daytime and nighttime temperature extremes

Study Configuration

• Spatial Scale: Regional (Middle East, approximately 6.93 million km2)
• Temporal Scale: Historical baseline period (1985–2014) and three future projection windows (2015–2044, 2045–2074, and 2075–2100)

Methodology and Data

• Models used: Stacking Ensemble Machine Learning (Stacking-EML)-refined CMIP6 global climate models (ACCESS-CM2, MRI-ESM2-0, MIROC6, GFDL-ESM4, MPI-ESM1-2-LR, and NorESM2-MM)
• Data sources: ERA5 reanalysis product

Main Results

• Projected changes in temperature extremes are substantial across the Middle East under all climate scenarios.
• Regional mean changes during 2075–2100 reach 73.93 and 65.87 percentage points for TX90p and TN90p, respectively.
• Projected changes are highly spatially organized, with the Arabian Peninsula consistently emerging as the principal hotspot of amplification.

Contributions

• This study provides a comprehensive assessment of projected temperature extremes across the Middle East under different climate scenarios.
• The analysis combines delta-based projections with Global Moran's I and Getis–Ord Gi* hotspot statistics to evaluate the spatial organization of projected temperature-extreme changes.
• The day–night asymmetry metrics developed in this study enable a spatially explicit assessment of whether daytime and nighttime extremes evolve in parallel or diverge systematically across the Middle East.

Funding

• This research was funded by the Iran National Science Foundation (INSF) under grant number 98007714.
• Additional support was provided by the University of Tehran Research Council.

Citation

@article{Khosravi2026Projected,
  author = {Khosravi, Younes and Ouarda, Taha B. M. J.},
  title = {Projected Spatial Asymmetry of Daytime and Nighttime Temperature Extremes in the Middle East under CMIP6 Warming},
  journal = {Scientific Reports},
  year = {2026},
  doi = {10.1038/s41598-026-68572-w},
  url = {https://doi.org/10.1038/s41598-026-68572-w}
}