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Glacier mass balance and runoff are simulated from 1955 to 2014 for the catchment (46% glacier cover) containing Chhota Shigri Glacier (Western Himalaya) using gridded data from three regional climate models: (1) the Rossby Centre regional atmospheric climate model v.4 (RCA4); (2) the REgional atmosphere MOdel (REMO); and (3) the Weather Research and Forecasting Model (WRF). The input data are downscaled to the simulation grid (300 m) and calibrated with point measurements of temperature and precipitation. Additional input is daily potential global radiation calculated using a DEM at a resolution of 30 m. The mass-balance model calculates daily snow accumulation, melt and runoff. The model parameters are calibrated with available mass-balance measurements and results are validated with geodetic measurements, other mass-balance model results and run-off measurements. Simulated annual mass balances slightly decreased from −0.3 m w.e. a−1 (1955–99) to −0.6 m w.e. a−1 for 2000–14. For the same periods, mean runoff increased from 2.0 m3 s−1 (1955–99) to 2.4 m3 s−1 (2000–14) with glacier melt contributing about one-third to the runoff. Monthly runoff increases are greatest in July, due to both increased snow and glacier melt, whereas slightly decreased snowmelt in August and September was more than compensated by increased glacier melt.

Meltwater runoff in the catchment area containing Chhota Shigri glacier (Western Himalaya) is simulated for the period 1951–2099. The applied mass-balance model is forced by downscaled products from four regional climate models with different horizontal resolution. For the future climate scenarios we use high resolution time series of 5 km grid spacing, generated using the newly developed Intermediate Complexity Atmospheric Research Model. The meteorological input is downscaled to 300 m horizontal resolution. The use of an ice flow model provides annually updated glacier area for the mass-balance calculations. The mass-balance model calculates daily snow accumulation, melt, runoff, as well as the individual runoff components (glacial melt, snowmelt and rain). The resulting glacier area decreases by 35% (representative concentration pathway (RCP) 4.5 scenario) to 70% (RCP 8.5 scenario) by 2099 relative to 2000. The average annual mass balance over the whole model period (1951–2099) was –0.4 (±0.3) m w.e. a–1. Average annual runoff does not differ substantially between the two climate scenarios. However, for the years after 2040 our results show a shift towards earlier snowmelt onset that increases runoff in May and June, and reduced glacier melt that decreases runoff in August and September. This shift is much stronger pronounced in the RCP 8.5 scenario.