Spatiotemporal changes of glaciers on Yulong Snow Mountain, southeastern Tibetan Plateau, from 1987 to 2024

Yulong Snow Mountain (YSM) represents the southern limit of modern temperate glacier distribution in China. This study examines glacier evolution over the period 1987–2024 using multi-source remote sensing data and mass balance observations of Baishui River Glacier No. 1 from 2008 to 2024. Over the past four decades, the glacierized area on YSM has declined by approximately 43%, from 7.53 km² to 4.29 km², accompanied by complex changes in glacier number and size structure. While the fragmentation of relatively larger glaciers (>0.5 km²) temporarily increased the count of smaller glaciers (0.2–0.5 km²), it concurrently masked the overarching trend of systemic glacier decline. Small, low-elevation glaciers on south-and west-facing slopes were the most vulnerable, with complete disappearance occurring in the Renhe River basin. In contrast, larger glaciers, though significantly reduced in area, persisted preferentially in shaded, high-elevation settings. Mass balance observations of Baishui River Glacier No. 1, the largest glacier on YSM, revealed persistent negative annual balances from 2008 to 2024, with a mean value of –1.47 m w.e./a and a cumulative loss of 24.91 m w.e. over the 17-year period. This work provides an updated glacier inventory for 2024 and an extended mass balance record for BRG1. Furthermore, it offers critical empirical evidence for understanding the response mechanisms of monsoonal temperate glaciers to climate change, revealing size-dependent, aspect-controlled, and elevation-sensitive patterns of glacier retreat under regional warming.