Analysis of historical climate change and its impacts on bread wheat (Triticum aestivum L.) production in Central Oromia, Ethiopia

Abstract

This study examines the impact of climate change on bread wheat (Triticum aestivum L.) yield in Central Oromia, Ethiopia, using climate and yield data from the past 32 years. Historical daily climate data were obtained from the Ethiopian Meteorological Institute, while observed wheat yield data were collected from the respective Zonal Agricultural Offices. Correlation analysis was used to assess climate–yield relationships, and simulated yield data were generated using multiple regression analysis to estimate yield responses to climate change. Trend and variability analyses were applied to evaluate climate patterns and their effects on wheat production. Results show significant increases in maximum temperatures at all stations, while minimum temperatures increased at 37.5%–75% of the stations. Annual rainfall increased at 37.5% of stations and decreased at 12.5%. Rainfall variability showed high concentration and irregular distribution, with annual precipitation concentration index values of 16%–20% and seasonal values exceeding 20%. Drought conditions, based on the Rainfall Anomaly Index, occurred in 72% of the years, classified as 22% extreme, 34% severe, and 44% moderate drought. The growing season started between 153 and 210 day of year (DOY) and ended at 275–282 DOY, lasting 101–120 days with 69–103 rainy days. Dry spell lengths during the growing season were below 5%, declined to nearly zero at peak season, and sharply increased in September, reaching 90%–100% by month's end across all stations. Climatic factors explained 43%–85% of wheat yield variability, although non-climatic factors also contributed. Overall, findings emphasize climate variability impacts on wheat production and the need for adaptive strategies and further research.