CMIP6 Multi-Model Ensemble Projections of Climate Change Impacts on Precipitation, Temperature, and Climate Extremes in the Anai Watershed, West Sumatera, Indonesia

Abstract

Climate change increasingly affects hydroclimatic conditions at the watershed scale. This study assessed the projected changes in precipitation, maximum and minimum temperatures, and climate extremes in the Anai watershed under the CMIP6 emissionscenarios SSP2-4.5 and SSP5-8.5. Three CMIP6 GCMs (NorESM2-MM, NorESM2-LM, and TaiESM1) were statistically downscaled and bias-corrected with observed precipitation and temperature data using CMhyd Software. Temporal trends were evaluated using theMann–Kendall test and Sen’s slope estimator, and 14 ETCCDI indices were analyzed to characterize future climate extremes. The results showed an increase in the projected annual precipitation and temperature, particularly under a higher emission scenario.Annual precipitation is projected to increase by approximately 3.04 mm/year under SSP2-4.5 and 4.04 mm/year under SSP5-8.5 emission scenario. The maximum temperature is projected to rise at 0.01 °C (SSP2.-4.5) and 0.04 °C (SSP5-8.5) while minimum temperature statistically not significant elevate under SSP 2-4.5 at 0.01 °C, and annually increase significantly under SSP5-8.5 at 0.03 °C conversely. Monthly projected precipitation and temperature tend to have similar patterns of projection compared to the historical period, with more climatic variability in the future. Furthermore, seasonal changes suggest more frequent heavy rainfall events and a decrease in cold nights in the future in the Anai watershed. These changes imply heightened risks of flooding, landslides, and heat stress, underscoring the need for climate-resilient watershed management and adaptation planning in the Anai watershed.