Beshir et al. (2025) Climate change projections using CMIP6 GCMs and downscaling approaches in the Upper Wabe Shebele Basin, Ethiopia

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-11-11
• Authors: Siraj Beshir, Awdenegest Moges, Mihret Dananto
• DOI: 10.1038/s41598-025-23194-6

Research Groups

• College of Agriculture and Natural Resources, Madda Walabu University, Bale Robe, Ethiopia
• Faculty of Biosystems and Water Resource Engineering, Institute of Technology, Hawassa University, Hawassa, Ethiopia

Short Summary

This study projected future precipitation and temperature changes in the Upper Wabe-Shebele River Basin, Ethiopia, using CMIP6 GCMs and downscaling techniques. Findings indicate a significant decline in precipitation (up to 50.33%) and a substantial increase in temperature (up to 3.6 °C) by the 2070s, threatening water availability and agricultural productivity.

Objective

• To examine anticipated changes in precipitation and temperature in the Upper Wabe-Shebele River Basin using CMIP6 Global Climate Models (GCMs) and downscaling approaches, providing high-resolution projections under multiple Shared Socioeconomic Pathway (SSP) scenarios to inform adaptation strategies.

Study Configuration

• Spatial Scale: Upper Wabe-Shebele River Basin (UWSRB), Ethiopia, covering an area of 10,259.03 km². Geographically located between 39°24′30.65′′ to 39°29′49.13′′ E and 6°53′44.63′′ to 7°27′37.75′′ N.
• Temporal Scale:
  • Baseline Period: 1986–2022 (for CMhyd) and 1986–2014 (for SDSM).
  • Future Projection Periods: 2023–2053 (near-to-medium term, referred to as 2040s) and 2054–2086 (long term, referred to as 2070s).

Methodology and Data

• Models used:
  • Global Climate Models (GCMs): Coupled Model Intercomparison Project Phase 6 (CMIP6), specifically CanESM5 (Canadian Earth System Model version 5).
  • Downscaling Models: Statistical Downscaling Model (SDSM) and CMhyd (Hydrologic Model, primarily for bias correction).
  • Bias Correction Techniques: Linear Scaling (LS), Distribution Mapping (DM), Empirical Quantile Mapping (EQM), and Power Transformation (PT) for precipitation; DM, EQM, LS, and Variance Scaling (VARI) for temperature.
• Data sources:
  • Historical daily precipitation, maximum, and minimum temperatures (1986–2022) from six meteorological stations (Adaba, Hunte, Kofale, Gobessa, Meraro, Arsi Robe) provided by the National Meteorological Services of Ethiopia (NMA).
  • Climate Forecast System Reanalysis (CFSR) and National Aeronautics and Space Administration (NASA) datasets for gap-filling in historical data.
  • Large-scale atmospheric variables (predictors) from the National Center for Environmental Prediction (NCEP) and the Canadian Centre for Climate Modeling and Analysis (CCCMA).
  • CMIP6 GCM simulations (CanESM5, MPI-ESM1-AR, NorESM2-MM), with CanESM5 selected for projections.
  • Shared Socioeconomic Pathways (SSPs): SSP1-2.6 (low emissions), SSP2-4.5 (medium emissions), and SSP5-8.5 (high emissions).
  • Qualitative data: Key informant interviews (KIIs) and focus group discussions (FGDs) with stakeholders and community representatives.

Main Results

• Historical Climate (1986–2022):
  • Mean annual precipitation: 1197.26 mm.
  • Mean annual temperature: 16 °C (average of 8.21 °C minimum and 20.84 °C maximum).
  • Observed temperature increase in Ethiopia over the last 30 years: 0.3 °C to 0.66 °C.
• Future Climate Projections (2023–2086) relative to baseline:
  • Precipitation:
    • Overall average annual precipitation reduction: 35.89%.
    • Under SSP5-8.5: projected decline of 41.76% in the 2040s and 50.33% in the 2070s.
    • Under SSP1-2.6: projected decline of 21.19% in the 2040s and 30.25% in the 2070s.
    • Monthly precipitation distributions are also expected to vary.
  • Temperature:
    • Overall average annual temperature increase: 2.03 °C (projected mean of 18.04 °C compared to historical 16 °C).
    • Projected increase range: 0.89 °C to 3.6 °C, depending on the emissions scenario and time period.
    • Under SSP5-8.5: projected increase of 2.21 °C in the 2040s and 3.6 °C in the 2070s.
    • Under SSP1-2.6: projected increase of 0.89 °C in the 2040s and 1.94 °C in the 2070s.
    • Monthly temperature distributions are also expected to vary.
• Impacts: These climatic changes are expected to significantly reduce water availability and agricultural productivity in the Upper Wabe-Shebele River Basin.
• Model Performance: SDSM demonstrated statistically better performance in reproducing observed historical climate data compared to CMhyd. Empirical Quantile Mapping (EQM) was identified as the most sensitive and effective bias correction method for CMhyd.

Contributions

• Provided a systematic evaluation and comparison of Statistical Downscaling Model (SDSM) and CMhyd performance for the Upper Wabe-Shebele River Basin.
• Generated high-resolution and improved climate projections for precipitation and temperature using CMIP6 GCMs under multiple Shared Socioeconomic Pathway (SSP) scenarios for a climatically vulnerable and data-scarce basin.
• Addressed limitations related to data gaps, spatial sparsity of observed meteorological datasets, and uncertainties inherent in CMIP6 outputs.
• Integrated downscaling approaches with climate change scenario analysis to offer a more detailed understanding of the basin’s diverse climatic conditions and regional variations.
• Produced valuable findings to inform the development of effective adaptation and mitigation strategies for water resource management and agriculture in the study area.

Funding

• The Ministry of Water and Energy and Ethiopia National Meteorology Service were acknowledged for data provision. No specific funding projects, programs, or reference codes for the research itself were listed.

Citation

@article{Beshir2025Climate,
  author = {Beshir, Siraj and Moges, Awdenegest and Dananto, Mihret},
  title = {Climate change projections using CMIP6 GCMs and downscaling approaches in the Upper Wabe Shebele Basin, Ethiopia},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-23194-6},
  url = {https://doi.org/10.1038/s41598-025-23194-6}
}