Future hydro-climatic changes associated with global warming and stratospheric aerosol intervention scenarios across Central-South Asia and the Tibetan Plateau

Abstract. The Central and South Asian Tibetan Plateau (CSATP) plays a vital role in regulating regional and downstream water availability. However, the region faces growing threats from global warming-induced hydroclimatic changes. This study investigates the hydro-climatic changes in the CSATP region under two future (2071–2100) scenarios of high greenhouse gas (GHG) emissions (SSP5-8.5) and the combined impact of GHG with stratospheric aerosol intervention (SAI), relative to present-day conditions (2015–2035). The temperature, precipitation, real evapotranspiration (RET), available water (AW), runoff, soil moisture (SM), terrestrial water storage (TWS), and leaf area index (LAI) are assessed using model simulations from CESM2-WACCM. These variables exhibit widespread intensification, with significant increases in temperature, precipitation, runoff, and LAI, particularly in eastern central Asia (ECA) and South Asia (SA), accompanied by enhanced seasonal amplitudes and earlier runoff peaks. These shifts indicate stronger seasonality and heightened extremes across the land surface. In contrast, the Geo SSP5-8.5 1.5 (here called Geo-SAI) scenario effectively reduces temperature and dampens the seasonal amplitude of TWS, runoff, RET, and precipitation, thereby counteracting many GHG-emission induced changes. However, Geo-SAI also amplifies seasonal variability in SM and vegetation (LAI), especially in ECA and the Tibetan Plateau (TP), revealing its regionally heterogeneous impacts on land–atmosphere interactions under solar geoengineering. While Geo-SAI does not entirely negate the impacts, it provides a viable pathway for reducing extremes and fostering climate stability in vulnerable regions. These results highlight the potential of SAI to alleviate the adverse hydroclimatic effects of GHG-induced warming in CSATP.