Glacier changes in Langtang Catchment, Central Nepalese Himalaya from the Little Ice Age (~1815 CE) to 2023 CE

Himalayan glaciers have experienced significant area and mass loss since the end of the Little Ice Age (LIA; ~mid-1800s to early-1900s), yet analysis of the patterns of recession and long-term, catchment-scale records remain scarce. Here, we reconstruct the extent and surface of glaciers at the LIA (~1815 CE) in the Langtang Catchment, Nepal Himalaya, using geomorphological indicators and balanced-ratio method, and quantify the long-term (LIA-1964/2023 CE) and recent (1964 to 2023 CE) changes in glacier extent based on Corona (1964/1974) and Sentinel (2016/2023) imagery, while examining climatic, topographic, and glaciological controls. Between the LIA and 2023, total glacier area decreased by 78.78 ± 4.38 km 2 (~41.5%), while glacier numbers nearly doubled from 58 to 115 due to separation, fragmentation, and disconnection. Glacier area loss rates increased more than fourfold, from 0.11% a −1 (LIA:1815–1964) to 0.49% a −1 (1964–2023) with further acceleration after 2000 (~0.79% a −1 during 2000–2016 and ~ 0.5% a −1 during 2016–2023). Glaciers in the catchment experienced widespread thinning, reduced flow velocities, and rising equilibrium-line altitudes (ELAs), coinciding with pronounced elevation-dependent warming (~0.3 °C dec −1 > 4000 m compared to 0.1 °C dec −1 at 3865 m a.s.l.; 1964–2023). Thinning progressively migrated up-glacier into accumulation zones, while rising ELAs increasingly intersected thinned and heavily crevassed icefall regions, driving glacier fragmentation and disconnection. Fragmented glaciers showed higher area loss, thinning rates, and reduced surface velocities, whereas disconnections in valley glaciers led to stagnation and degradation of debris-covered tongues. Our study highlights the critical need to assess glacier fragmentation and disconnection across the Himalaya. With enhanced warming at higher elevations, fragmentation and disconnection will likely dominant glacier recession in the region, with significant implications for future glacier evolution, meltwater availability, regional hydrology and associated geohazards.