Multi-scenario Hydro-climatic Mean and Peak Responses of Central–South Asia and the Tibetan Plateau to Future Warming and Stratospheric Aerosol Intervention

Abstract. Central–South Asia and the Tibetan Plateau are climate-sensitive regions where water resources are controlled by monsoon, westerlies, and cryosphere processes. This study evaluates hydroclimatic changes across three regimes: moisture-limited Central Asia (west (WCA) and east (ECA)), cryosphere-influenced Tibetan Plateau (TIB), and monsoon-dominated South Asia (SAS), under warming (SSP2-4.5, SSP5-8.5) and solar radiation management (SRM) scenarios with temperature-stabilized (G6-1.5K-SAI and Geo-SAI) and transient forcing (G6solar and G6sulfur) experiments using CESM2-WACCM for 2055–2084 relative to 2015–2034. Warming substantially amplifies annual peak hydroclimatic responses, with peak temperature increasing by 24 %, ET by 6.5 %, precipitation by up to 13 % in TIB and SAS, and available water (AW) by 18 %–23 %, alongside accelerated cryosphere melts and enhanced vegetation. In contrast, dry Central Asia shows smaller precipitation and AW increases but remains highly sensitive to evapotranspiration (ET)-driven drying and soil moisture (SM) losses. Temperature-stabilized scenarios provide stronger and more consistent suppression of warming and extremes, while transient forcing scenarios achieve only partial mitigation and retain greater variability. Across regions, SRM generally reduces temperature and ET, produces mixed precipitation responses, and partially restores AW, soil moisture, and cryosphere-related processes. The findings per unit sulfur injected exhibit highest cooling and hydrological efficiency under G6-1.5K-SAI, showing that effectiveness depends on both sulfur loading and injection strategy. SRM also moderates cryosphere loss through enhanced snowfall and reduced snowmelt over the TIB. Warming intensifies seasonal variability and advances peak timing, whereas SRM dampens these shifts to present-day conditions. Precipitation remains the dominant control on AW, indicating that SRM primarily modifies hydroclimatic magnitude rather than underlying water-cycle controls. Overall, SRM reduces hydroclimatic extremes but cannot fully offset regional water stress, and its effectiveness depends on both forcing pathway and intervention strategy, highlighting the need for climate-regime-specific and sulfur-normalized evaluation.