Getachew et al. (2025) Exploring the dynamics of past and future climate extremes under CMIP6: implications for rainfed agriculture

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-10-29
• Authors: Fikadu Getachew, Haimanote K. Bayabil, Gerrit Hoogenboom, Gregory A. Kiker, Ziwen Yu, Li Y
• DOI: 10.1007/s00704-025-05824-1

Research Groups

• Department of Agricultural and Biological Engineering, Tropical Research and Education Center, IFAS, University of Florida, Homestead, FL, USA
• Department of Agricultural and Biological Engineering and Food Systems Institute, University of Florida, Gainesville, FL, USA
• Department of Soil and Water Sciences, Tropical Research and Education Center, IFAS, University of Florida, Homestead, FL, USA

Short Summary

This study examined the projected climate extremes trends and changes in occurrences in Ethiopia using eight temperature and precipitation-related indices under CMIP6 scenarios. Results indicated that Ethiopia’s rainfed agriculture system will likely face exacerbated and frequent severe droughts, posing significant challenges to food security.

Objective

• To determine the spatial and temporal trends of climate extremes (temperature and precipitation-based indices) in Ethiopia under CMIP6 projections (SSP245 and SSP585) for two future periods (2035s and 2065s), and assess their implications for rainfed agriculture.

Study Configuration

• Spatial Scale: All regions of Ethiopia (3°–15° N and 33°–48°E) at a gridded resolution of 0.05° x 0.05° (approximately 5 km x 5 km).
• Temporal Scale:
  • Baseline period: 1981–2010
  • Future periods: 2035s (2021–2050) and 2065s (2051–2080)
  • Seasonal analysis focused on the main rainy season (June to September, JJAS).

Methodology and Data

• Models used:
  • Global Climate Models (GCMs) from CMIP6: GFDL-ESM4, MPI-ESM1-2-HR, MRI-ESM2-0, UKESM1-0-LL.
  • Shared Socioeconomic Pathways (SSPs): SSP245 (medium challenge to mitigation and adaptation) and SSP585 (high fossil-fuel-based development).
  • Downscaling method: Bias Correction/Constructed Analogues with Quantile Mapping Reordering (BCCAQ) technique using the "ClimDown" R package.
  • Climate Extreme Indices (CEI) computation: Climate Data Operator (CDO version 2.0.2) and NetCDF Operators (NCOs) for eight ETCCDI indices (CDD, CWD, R20, Rx1day, ETR, CSU, HWDI, SPI).
  • Standardized Precipitation Index (SPI) computation: National Center for Atmospheric Research (NCAR) Command Language (NCL).
  • Trend analysis: Linear regression model, non-parametric Mann–Kendall test (p-value < 0.1), and Sen’s slope estimator using the "Trend" R package.
• Data sources:
  • Historical gridded daily precipitation data: Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) (0.05° x 0.05°).
  • Historical gridded daily minimum and maximum temperature data: AgMIP Modern-Era Retrospective Analysis for Research and Applications (AgMERRA) (0.5° x 0.5°).
  • Observed station data for validation: Daily maximum temperature, minimum temperature, and rainfall from seven meteorological stations in Ethiopia (Melkassa, Meisso, Babile, Metehara, Jijiga, Kobo, and Debarik) for the baseline period (1981–2010).

Main Results

• Consecutive dry days (CDD) are projected to increase by up to 40 additional days per climatological period, particularly in southeastern Ethiopia.
• Consecutive wet days (CWD) are projected to decrease by up to 10 days in northern and southeastern regions, though some areas may experience increases of up to 40 days.
• Days with heavy precipitation (R20, > 20 mm/day) are expected to increase by up to 40 days in northwestern Ethiopia (UKESM10LL model), while most regions will see changes between -5 and 5 days.
• Maximum 1-day precipitation (Rx1day) is projected to become more intense in central and southeastern highlands, with values exceeding 200 mm/day in some areas.
• Standard Precipitation Index (SPI) results indicate more frequent severe droughts (SPI < -1.5), particularly affecting central, southern, and southwestern regions, with projections of extreme drought frequency of once in four years.
• Consecutive summer days (CSU, > 36 °C) are projected to increase by up to 80 days in the northeast and southeast (UKESM10LL model).
• The heatwave duration index (HWDI) is estimated to increase by an average of 30 days during the main rainy season in northern and eastern areas.
• Concurrent drought analysis reveals that current agricultural production regions, especially east of the Rift Valley, will likely be significantly affected by co-existing severe drought, longer CDD, longer CSU, and large ETR, leading to the marginalization of peripheral agricultural lands.
• The UKESM10LL and MPI-ESM12HR models showed notable regional variations in projections.

Contributions

• Provides comprehensive, high-resolution (0.05° x 0.05°) spatial and temporal projections of eight temperature and precipitation-based climate extreme indices for all regions of Ethiopia under CMIP6 (SSP245 and SSP585).
• Highlights the specific vulnerabilities of Ethiopia's rainfed agriculture to future climate extremes, including exacerbated and frequent severe droughts, prolonged dry spells, increased heatwaves, and concurrent extreme events.
• Offers critical information for stakeholders and policy development to guide climate change adaptation measures and ensure sustainable agricultural production in Ethiopia.
• Addresses a previous lack of comprehensive information on spatial and temporal projections of climate extremes for most regions of Ethiopia, extending beyond historical periods or specific locations.

Funding

• University of Florida Institute of Agricultural and Food Sciences (UF/IFAS) (assistantship for the senior author).
• National Institute of Food and Agriculture, U.S. Department of Agriculture, through the Hatch Project No. FLA-TRC-006424.
• Prince Albert II of Monaco Foundation through the IPCC Scholarship.

Citation

@article{Getachew2025Exploring,
  author = {Getachew, Fikadu and Bayabil, Haimanote K. and Hoogenboom, Gerrit and Kiker, Gregory A. and Yu, Ziwen and Y, Li},
  title = {Exploring the dynamics of past and future climate extremes under CMIP6: implications for rainfed agriculture},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05824-1},
  url = {https://doi.org/10.1007/s00704-025-05824-1}
}