Spatiotemporal Trends in Extreme Temperature and Rainfall Indices in Central and Northwest Tigray, Ethiopia: Implications for Agriculture and Climate Change Adaptation

The northern part of Ethiopia is vulnerable to extreme droughts, which subsequently affect agricultural production and food security. This study therefore, analyzed the spatiotemporal variability of extreme temperature and rainfall across ten selected observation stations in the central and northwest zones of Tigray using a long-term climate data obtained from NASA POWER (1983-2023). The data were subjected to rigorous quality control analysis using the RClimDex v.1 software to detect potential erroneous or missing values. Trend analysis was performed on 21 of the 27 extreme temperature and rainfall indices recommended by the joint CCL/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI). The non-parametric Mann-Kendall trend test and Sen’s slope estimator were employed to determine the trends in temperature and rainfall across the study areas over the past forty years. The trend analysis demonstrated a highly significant (p < 0.01) increase in warming indicators such as warm nights (TN90p), warm days (TX90p), maximum value of the daily maximum (TXx), and minimum (TNx) temperature ranges, while cooling indicator indices like cold spell duration indicator (CSDI), cool nights (TN10p), and cool days (TX10p) exhibited a highly significant negative trend over the study period. Furthermore, TXx and TNx increased at rates ranging from 0.02 to 0.025 °C per year and 0.013 to 0.016 °C per year, respectively. Annual rainfall showed an increasing trend ranging from 0.38 to 3.5 mm per year. Notably, the frequency of heavy (R10mm) and extremely heavy (R25 mm) rainfall events revealed a highly significant (p < 0.01) positive trend, raising risks of flooding, soil erosion, and crop failure for local farmers. These findings highlight the urgent need for adaptive strategies to protect Tigray’s agriculture and livelihoods under changing climatic conditions.