High-resolution assessment of climate change impacts on the surface energy and water balance in the glaciated Naryn River basin, Central Asia.

Mountain regions of Central Asia are experiencing strong influences from climate change, with significant reductions in snow cover and glacial reserves. A comprehensive assessment of the potential consequences under the worst-case climate scenario is vital for adaptation measures throughout the region. Water balance analysis in the Naryn River basin was conducted for the baseline period of 1981-2000 including potential changes under the worst-case SSP5-8.5 scenario for 2077-2096 by combining high-resolution (5 km) regional climate projections with fully distributed glacio-hydrological (1 km) modeling. Results showed that with the complete degradation of glaciers and increase in evapotranspiration, the overall runoff will decrease by 16%, and in the upper basins, the reduction will exceed 40%. The maximum snow water equivalent (SWE) is projected to decrease by 17%, and the seasonal peak of SWE will occur one month earlier. The transition from snow to rain will significantly affect lower regions, increasing extremes in peak runoff and causing 10-year recurrence interval events to occur every 3-4 years. Moreover, extreme runoff in high mountainous areas will increase due to intensified snowmelt and increased rainfall extremes. Additionally, a gradient of surface soil temperature change of 0.1 °C per 100 m elevation gain was observed, suggesting a potential snow-albedo feedback effect that could further amplify the warming, especially at higher altitudes. This study provides a robust analytical framework to assess the complex responses of mountain ecosystems to the impacts of climate change, with the potential of widespread application for addressing the challenges facing these critical regions.