Ice loss from asymmetric melting at Thwaites Glacier grounding zone
Abstract
Thwaites Glacier drains a significant portion of the West Antarctic Ice Sheet and is grounded below sea level, which makes it susceptible to runaway melting from a warming ocean, often referred to as the marine ice sheet instability. Recent acceleration in ice flow, reduced area of the floating ice tongue and shelf, and retreat of the grounding line argue that rapid ice loss is likely to continue. We report the first in situ observations extending 3 km from the grounding zone of Thwaites Eastern Ice Shelf and from the ice-ocean interface to the seafloor that resolve ice shelf melting at fine-scale. These observations reveal a rough ice base and seafloor sloping upward towards the grounding line. We show that the warmest water exceeds 2°C above freezing and infiltrates the cavity near the grounding line. Under these conditions, the ice shelf base evolves from corrugated with irregular slopes inherited from the upstream bed to stair cased sequences of steep-sided terraces. Data closest to the ice base show that strong melting occurs along sloped surfaces, producing stratification that suppresses melt along flat interfaces. This effect is pronounced within crevasses, and implies that ice loss under ice shelves is strongly influenced by ice base topography of the grounding zone.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.C35A0867W