Al-Timimi et al. (2026) Effects of climate change on temperature and precipitation in the Euphrates-Tigris Basin

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2026
• Date: 2026-03-14
• Authors: Yaseen K. Al-Timimi, Alaa M. Al-Lami, Monim H. Al-Jiboori, Ayad M. Fadhil Al-Quraishi
• DOI: 10.1007/s00704-026-06169-z

Research Groups

• Department of Atmospheric Sciences, College of Science, Mustansiriyah University, Baghdad, Iraq
• Petroleum and Mining Engineering Department, Tishk International University, Erbil, Iraq

Short Summary

This study comprehensively assesses projected climate change impacts on temperature and precipitation across the entire Euphrates-Tigris Basin under four RCP scenarios (2.6, 4.5, 6.0, 8.5) for three future periods, revealing a consistent warming trend and significant spatial redistribution of precipitation, with severe implications for downstream water resources.

Objective

• To assess the projected climate change for the Euphrates-Tigris Basin (ETB) using the IPCC Representative Concentration Pathway (RCP) 2.6, 4.5, 6.0, and 8.5 scenarios.
• To compare the latest climate model projections of precipitation and temperature for different scenarios to identify potential future changes in this region.

Study Configuration

• Spatial Scale: Euphrates-Tigris Basin (ETB), approximately 878,000 km², encompassing Turkey, Syria, Iraq, and Iran. The analysis was performed at a spatial resolution of 1.25° × 0.95°.
• Temporal Scale:
  • Historical baseline: 1961–1990 (30 years)
  • Future periods: 2016–2040 (near-term), 2041–2069 (mid-term), and 2070–2099 (long-term).

Methodology and Data

• Models used: Global Climate Models (GCMs), specifically outputs from the Community Earth System Model (CESM). The CMhyd tool was used for bias correction of simulated data against observed data.
• Data sources: Dynamically downscaled datasets for temperature and precipitation from the National Center for Atmospheric Research (NCAR) program archives’ Community Earth System Model (CESM) website. Four Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) were utilized. Observed data from the Baghdad meteorological station were used for model performance assessment.

Main Results

• A significant and consistent warming trend is projected across the entire Euphrates-Tigris Basin under all RCP scenarios.
• Basin-average temperature increases by 2099 are projected to be 1.65 °C (RCP2.6), 2.65 °C (RCP4.5), 3.15 °C (RCP6.0), and 4.76 °C (RCP8.5) compared to the 1961–1990 baseline.
• The warming is more pronounced in high-upstream regions (eastern Anatolia and southeastern Zagros mountains), with local increases exceeding 5.0 °C under RCP8.5 by the end of the century.
• Precipitation patterns show greater variability, with negative anomalies being stronger and more prevalent in the central areas of the Northern-Highland during mid- and long-term periods across all scenarios.
• The largest precipitation reductions are seen under RCP6.0 and RCP8.5, with century-end decreases generally between 20 mm and 90 mm in key water-yielding regions.
• A north-south dipole pattern is observed, with reduced precipitation in northern latitudes and weakly positive anomalies in arid/semi-arid southern plains, which are insufficient to counterbalance upstream deficiencies.
• These changes indicate severe hydroclimatic stress, increasing hydrological risk in downstream countries, particularly Iraq, due to rising evaporative demand, accelerated snowmelt, and restricted snowpack accumulation.

Contributions

This study addresses existing gaps in the literature by providing a comprehensive, basin-wide characterization of projected temperature and precipitation changes across the entire Euphrates-Tigris Basin. It synthesizes multiple Representative Concentration Pathway (RCP) scenarios and future timeframes, offering a more detailed explanation of future hydroclimatic changes compared to previous fragmented studies that focused on sub-regions, individual scenarios, or older climate models. The findings provide scientific justification for future hydrological impact and climate adaptation analyses.

Funding

This research received no specific grants from any funding agency in the public, commercial, or not-for-profit sectors. However, the authors acknowledge scientific support from Mustansiriyah University and data provision from the National Aeronautics and Space Administration (NASA).

Citation

@article{AlTimimi2026Effects,
  author = {Al-Timimi, Yaseen K. and Al-Lami, Alaa M. and Al-Jiboori, Monim H. and Al-Quraishi, Ayad M. Fadhil},
  title = {Effects of climate change on temperature and precipitation in the Euphrates-Tigris Basin},
  journal = {Theoretical and Applied Climatology},
  year = {2026},
  doi = {10.1007/s00704-026-06169-z},
  url = {https://doi.org/10.1007/s00704-026-06169-z}
}