Temporary slow-down associated with drainage of a large subglacial lake, Totten Glacier, East Antarctica

We present observations documenting the drain–fill cycle of a large subglacial lake and the associated velocity response on the Totten Glacier, East Antarctica. The lake transitioned from a period of stability to rapid drawdown, dropping by more than 50 m in less than a year. Following drainage, glacier flow speed decelerated by ~100 m yr⁻¹ (~20%) over the lake and by ~30 m yr⁻¹ in a region immediately downstream. We hypothesize that the pronounced slowdown over the lake reflects complete drainage and increased basal traction associated with grounding, while the downstream deceleration results from disruption of the subglacial hydrologic system. Over the subsequent three years, as the lake refilled, glacier flow speeds recovered to pre-drainage levels.