Spatiotemporal Analysis of Temperature Extremes under Future Climate Scenarios in the Borana Zone, Ethiopia

<title>Abstract</title> <p>Climate change has intensified temperature extremes worldwide, with particularly severe implications for semi-arid regions such as southern Ethiopia. This study assessed historical and future temperature extremes across the Borana Zone using ENACTS observational datasets (1985–2014) and bias-corrected outputs from nine CMIP6 global climate models under SSP2-4.5 and SSP5-8.5 scenarios. Extreme temperature indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) were computed using the Climate Data Tool. Model performance was evaluated using correlation coefficient, mean error, mean absolute error, root mean square error, and index of agreement. Long-term trends were assessed using the Mann–Kendall test and Sen's slope estimator, while Pearson correlation analysis was employed to investigate relationships between temperature extremes and major large-scale climate indices, including ENSO, PDO, IOD, SOI, and AMO. Results indicate statistically significant increases in warm temperature indices (TN90p, TX90p, TNx, TXx) and significant decreases in cold extremes (TN10p and CSDI), indicating an overall warming climate with stronger nighttime warming. Future projections show substantial increases in mean temperature and warm spell duration under both emission scenarios, with the highest warming projected under SSP5-8.5 by the late twenty-first century. Diurnal temperature range is projected to decrease, reflecting accelerated increases in minimum temperature relative to maximum temperature. Significant relationships between several temperature extremes and large-scale climate indices demonstrate the influence of global climate variability on regional temperature behavior. These findings provide important scientific evidence for climate adaptation planning, drought preparedness, and sustainable management of pastoral systems in the Borana Zone.</p>