Ayalew et al. (2026) Observed and projected climate extremes in northwest highlands of Ethiopia and their implications in potato-based farming systems

Identification

• Journal: Scientific Reports
• Year: 2026
• Date: 2026-04-05
• Authors: Asrat Ayalew, Mezegebu Getnet, Dereje Ademe, Achenafi Teklay, Aleminew Tagele, Shegaw Getu
• DOI: 10.1038/s41598-026-47373-1

Research Groups

• Department of Plant Sciences, College of Agriculture and Environmental Sciences, University of Gondar, Gondar, Ethiopia
• Stichting Wageningen Research, Addis Ababa, Ethiopia
• Department of Horticulture, College of Agriculture and Natural Resources, Debre Markos University, Debre Markos, Ethiopia
• Department of Soil, Water and Ecosystem Sciences, Institute of Sustainable Food and Agricultural Systems, University of Florida, Gainesville, USA
• Department of Environmental Engineering, College of Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia

Short Summary

This study analyzed observed (1989-2018) and projected (2019-2078) extreme rainfall and temperature trends in northwest Ethiopian highland agroecosystems, revealing significant increases in both extreme precipitation and temperature events, particularly in the Upper Dega and under high emission scenarios, with critical implications for potato-based farming systems.

Objective

• To analyze observed (1989-2018) and projected (2019-2078) changes in rainfall and temperature extremes across upper and lower highland agroecosystems (AESs) in northwest Ethiopia at annual and seasonal time scales, specifically focusing on implications for potato-based farming systems to inform tailored adaptation strategies.

Study Configuration

• Spatial Scale: Northwest highlands of Ethiopia, specifically Debark, Dabat, and Wogera districts. The study area is categorized into Lower Dega (lower highland) and Upper Dega (upper highland) agroecosystems, situated at an elevation range of 2685–2948 meters above sea level.
• Temporal Scale:
  • Observed: 1989–2018 (30 years).
  • Projected: Near-term (NT) (2019–2048) and Mid-century (MC) (2049–2078) under moderate (SSP2-4.5) and high (SSP5-8.5) emission scenarios.
  • Seasonal: Bega (dry season; October–January), Belg (short rainy season; February–May), and Kiremt (main rainy season; June–September).

Methodology and Data

• Models used:
  • RClimDex2.0 (for computing extreme climate indices)
  • Modified Mann–Kendall test and Sen’s slope estimator (for trend significance and magnitude)
  • MIROC6 (Model for Interdisciplinary Research on Climate, version 6) for future climate projections.
  • CMhyd (Climate Model data for hydrologic modeling) for bias correction of climate model outputs.
  • Penalized maximal F test, RHtestsV3, and RHtests_dlyPrcp (for data homogeneity and artificial break detection).
• Data sources:
  • Enhancing National Climate Services (ENACTS) dataset (observed daily precipitation, maximum temperature, and minimum temperature for 1989–2018, 4 km grid, blended station, satellite, reanalysis, and elevation data).
  • Coupled Model Intercomparison Project Phase 6 (CMIP6) archive (future climate change data under SSP2-4.5 and SSP5-8.5 scenarios).
  • NASA’s Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) system (bias-corrected, high-resolution (0.25°) MIROC6 data).

Main Results

• Observed Climate Extremes (1989-2018):
  • Precipitation: Upper Dega AES showed significantly higher increases in extreme rainfall intensity indices. Annual total wet day rainfall (PRCPTOT) increased by 168 mm per decade in Upper Dega and 66.6 mm per decade in Lower Dega. Monthly maximum consecutive five-day precipitation (RX5day) increased by 13.8 mm per decade in Upper Dega and 6.6 mm per decade (during Belg season) in Lower Dega. Consecutive wet days (CWD) significantly increased in both AESs, while consecutive dry days (CDD) showed an insignificant increase.
  • Temperature: Summer days (SU25) significantly increased (30 days per decade in Lower Dega, 16 days per decade in Upper Dega), while chill days (FD10) significantly decreased (39 days per decade in Lower Dega, 19 days per decade in Upper Dega). Maximum daily maximum temperature (TXx), minimum daily maximum temperature (TXn), and maximum daily minimum temperature (TNx) showed significant increasing trends in both AESs, with Lower Dega generally exhibiting a higher rate of increase. Cold days (TX10P) declined significantly, while warm days (TX90P) and warm nights (TN90P) increased significantly. Annual and Kiremt season diurnal temperature range (DTR) increased significantly in both AESs (e.g., 0.9 °C per decade in Lower Dega and 0.4 °C per decade in Upper Dega during Kiremt).
• Projected Climate Extremes (2019-2078):
  • Precipitation: Almost all precipitation extreme indices are projected to increase, with greater increases under the high emission scenario (SSP5-8.5), especially in Upper Dega. Annual PRCPTOT is projected to increase by 5.20% (near-term, SSP2-4.5) to 13.11% (mid-century, SSP5-8.5) in Lower Dega, and 8.70% (near-term, SSP2-4.5) to 16.29% (mid-century, SSP5-8.5) in Upper Dega. Higher intensity indices like extremely wet days (R99P), number of very heavy precipitation days (R20), and RX5day are projected to increase significantly (e.g., R99P by 20.24% in Lower Dega and 35.17% in Upper Dega under SSP5-8.5 in mid-century). CDD is projected to rise substantially (up to approximately 40% in Lower Dega and 30% in Upper Dega under SSP5-8.5).
  • Temperature: SU25 is projected to rise steadily (e.g., approximately 62 days in Lower Dega and 24 days in Upper Dega under SSP5-8.5 in mid-century), while FD10 is projected to decline (e.g., approximately 111 days in Lower Dega and 101 days in Upper Dega under SSP5-8.5 in mid-century). TXx, TNx, TXn, and TNn are projected to rise, with the largest increases for TXx and TNx during mid-century under SSP5-8.5 (e.g., TXx: 1.74 °C in Lower Dega, 1.65 °C in Upper Dega; TNx: 1.77 °C in Lower Dega, 1.95 °C in Upper Dega). DTR is projected to decrease in most scenarios and timeframes.

Contributions

• Addresses a critical gap in understanding the magnitude and trajectory of extreme climate indices at the agroecosystem (AES) level and seasonal time scales for potato-based farming systems in the northwest Ethiopian highlands.
• Provides a localized evidence base to support tailored adaptation strategies for sustainable potato production, considering the unique physiological requirements of the crop.
• Explicitly differentiates and interprets results for Lower Dega and Upper Dega AESs, offering insights relevant to their specific agricultural activities.
• Links observed historical climate extreme patterns to future projections, enabling anticipation of risk areas and timing for agricultural interventions.

Funding

• The University of Gondar, Ethiopia.

Citation

@article{Ayalew2026Observed,
  author = {Ayalew, Asrat and Getnet, Mezegebu and Ademe, Dereje and Teklay, Achenafi and Tagele, Aleminew and Getu, Shegaw},
  title = {Observed and projected climate extremes in northwest highlands of Ethiopia and their implications in potato-based farming systems},
  journal = {Scientific Reports},
  year = {2026},
  doi = {10.1038/s41598-026-47373-1},
  url = {https://doi.org/10.1038/s41598-026-47373-1}
}