Rising Lake Levels Across High Mountain Asia

Abstract. High-altitude lakes across High Mountain Asia (HMA) are one of the critical freshwater reservoirs and sensitive indicators of climate change due to their remote locations and limited human disturbances. This study presents continuous water level estimates for 232 lakes across HMA from 2010 to 2024 using CryoSat-2 and ICESat-2 data. We analyzed temporal and spatial variations and inter-mission consistency in the lake water level across HMA. Our results reveal an overall increasing trend (median rate: +0.1 ± 0.01 m yr⁻¹), with 77 % of lakes experiencing rising levels and 91 % exhibiting statistically significant trends. We find a substantial regional heterogeneity with the Tibetan Plateau contributing dominantly to regional increase (0.07 ± 0.001 m yr⁻¹), while Himalayan lakes show persistent decline (0.04 ± 0.001 m yr⁻¹). Water level times series observed with the satellite altimetry missions CryoSat-2 and ICESat-2 intercomparison demonstrates strong consistency (80 % sign agreement, p = 0.013). Lake catchment scale analysis identifies precipitation as the dominant deriver of lakes water level variability (r = 0.42, p < 0.001), whereas lakes in glaciated catchments exhibit weak climate correlations despite significant increases in temperature, indicating nonlinear cryosphere buffering. We find systematic relationships between lake characteristics (area, elevation) and increasing water levels, with larger lakes generally showing more rapid growth. The contrasting hydrological responses with continued rising water levels in cryosphere influenced lakes and accelerating declines in precipitation sensitive lakes in Himalaya highlight divergent lake hydrological regimes. These findings underscore the critical importance of regional differentiation in understanding lake water storage changes and informing climate adaptation strategies for population vulnerable to these changes in the regions.