Unprecedented 2025 glacier mass loss in Pamir

Recent extreme heat events have caused exceptional glacier mass loss worldwide. However, their impact on Pamir–Karakoram glaciers with anomalously stable or slightly positive mass balances remains unclear. Based on glaciological mass balance observations, meteorological records and surface albedo analysis, this study reports the unprecedented glacier mass loss of Kangxiwa Glacier in the eastern Pamir during the 2025 balance year. Kangxiwa Glacier experienced a record-breaking negative annual mass balance of −1.5 ± 0.15 m w.e. in 2025, which was substantially more negative than the historical average (−0.36 ± 0.14 m w.e. per year in 2010‒2024). Correspondingly, the surface albedo of Kangxiwa Glacier reached the lowest level since 2003, particularly in August and September. Under the persistent dominance of the upper-level anticyclonic (high pressure) atmospheric pattern modulated by Rossby waves and soil moisture, Kangxiwa Glacier experienced unprecedented and persistent high temperatures from May to September, inducing extreme glacier mass loss. Such record-breaking glacier mass loss was widespread among other glaciers across the Pamir. In the context of global warming, the increasing frequency of extreme heat events is likely to accelerate glacier ablation in Pamir, highlighting the importance of continuous meteorological and glaciological observations in this region.