Acceleration of an Antarctic outlet glacier driven by surface meltwater input to the base.

Abstract

Despite its importance and being commonly accepted in other regions, meltwater influence on the Antarctic ice sheet dynamics continues to be debated and questioned. To investigate the possible impact of surface melt on subglacial water pressure and ice dynamics, we performed hot-water drilling ~1 km upglacier from the grounding line of Langhovde Glacier in East Antarctica. Borehole measurements revealed that the subglacial water pressure exceeded 90% of the ice overburden and the pressure elevated during periods of intensive melting and rain. Coinciding with these events, ice speed increased by 10-20% and the surface rose by ~0.1 m. Subglacial water was freshwater, but hydraulically connected to the sub-shelf cavity, where sessile animals were distributed in a thin seawater layer. Our in-situ measurements confirm meltwater-driven acceleration of grounded ice in Antarctica. Since meltwater is ubiquitous along the Antarctic coast, its impact on outlet glacier dynamics should be considered when projecting Antarctic ice sheet evolution.