Impact of the 2022 heatwave and 2023 extreme summer snowfall on the mass balance of the Chhota Shigri Glacier, western Himalaya.

In summer 2022, extreme heatwaves affected many mountain ranges across the Northern Hemisphere-including the Himalaya, Alps, Rockies, and Tibetan Plateau-causing exceptional glacier mass loss. Chhota Shigri Glacier, a benchmark site for long-term monitoring in the western Himalaya, has recorded an average mass balance of - 0.47 ± 0.19 m w.e. a⁻¹ over 2002-2023. The 2021-22 hydrological year was characterized by pronounced spring and summer warming, resulting in the most negative annual mass balance in the observational record (-1.71 ± 0.24 m w.e. a⁻¹). In contrast, the following year (2022-23) exhibited a slightly positive mass balance (0.22 ± 0.27 m w.e. a⁻¹), despite 2023 registering the highest global mean temperature on record. This anomalous outcome was associated with cooler spring conditions (-1.16 °C anomaly) and exceptionally high summer precipitation. A major snowfall event in July 2023 delivered > 300 mm of precipitation over three days during the peak ablation season, increasing surface reflectivity and coinciding with a marked reduction in modeled melt. Although not derived from a full surface energy balance analysis, multiple independent indicators consistently support the interpretation of snowfall-induced melt suppression. Contrasting years such as 2021-22 and 2022-23 underscore the growing dominance of extreme weather events under continued warming. While positive mass balance years, such as 2022-23, represent a blip in the long-term glacier wastage trend, they should not be misinterpreted as a sign against ongoing climate change.