The 2020 abrupt drainage of Jinwuco triggered lake- to land- terminus transition and lagged slowdown of Jinwu Glacier, southeastern Tibet

Abstract. Glacier–proglacial lake interactions can accelerate terminus retreat and dynamic thinning of lake-terminating glaciers. However, glacier responses to abrupt lake disconnection following glacial lake outburst floods (GLOFs) remain poorly quantified. Here, we investigate changes in surface velocity (2017–2025) and elevation (2002–2025) of Jinwu Glacier (southeast Tibet, China), whose proglacial lake (Jinwuco) drained during a GLOF on 26 June 2020, shifting the glacier from lake- to land-terminating conditions. Rapid lake drainage triggered a pronounced but lagged dynamic response. Ice-flow velocities within 0–200 m of the terminus decreased by ~49 %, from ~40 m a⁻¹ (2017–2020) to ~20 m a⁻¹ (2022–2025). In contrast, velocity reductions in the upstream reach (600–1550 m) were smaller (~14 %). Surface elevation thinning in the terminal 0–550 m section intensified from −2.90 m a⁻¹ during 2002–2014 to −3.71 m a⁻¹ during 2014–2025, whereas surface lowering in the 600–1550 m section slowed from −1.17 to −0.87 m a⁻¹, with a slight surface elevation increase in the topographic transition zone (500–750 m). Following the GLOF, the glacier terminus underwent slight advance and localized ice calving. These patterns suggest a short-lived longitudinal extension at the glacier terminus, followed by a shift toward a more compressive regime in the 500–750 m zone as downstream ice-flux demand weakened. This study provides the first quantitative evidence of glacier dynamic adjustment following a GLOF driven transition from lake- to land-terminating conditions.