Detailed Seismic Bathymetry Beneath Ekström Ice Shelf, Antarctica: Implications for Glacial History and Ice‐Ocean Interaction

Emma C Smith,Dieter Franke,Andreas Läufer,Olaf Eisen,Christoph Gaedicke,Reinhard Drews,Tore Hattermann,Gerhard Kuhn,Ralf Tiedemann,Christoph Mayer,Coen Hofstede,Rapahel Gromig,Astrid Lambrecht,Todd A Ehlers,Sophie Berger,Frank Wilhelms

doi:10.1029/2019gl086187

Abstract

AbstractThe shape of ice shelf cavities are a major source of uncertainty in understanding ice‐ocean interactions. This limits assessments of the response of the Antarctic ice sheets to climate change. Here we use vibroseis seismic reflection surveys to map the bathymetry beneath the Ekström Ice Shelf, Dronning Maud Land. The new bathymetry reveals an inland‐sloping trough, reaching depths of 1,100 m below sea level, near the current grounding line, which we attribute to erosion by palaeo‐ice streams. The trough does not cross‐cut the outer parts of the continental shelf. Conductivity‐temperature‐depth profiles within the ice shelf cavity reveal the presence of cold water at shallower depths and tidal mixing at the ice shelf margins. It is unknown if warm water can access the trough. The new bathymetry is thought to be representative of many ice shelves in Dronning Maud Land, which together regulate the ice loss from a substantial area of East Antarctica.

Highlights

Ice shelves surrounding Antarctica act as buttresses, restraining ice discharge from the continent into the oceans, and regulating Antarctic contributions to sea level rise (Dupont & Alley, 2005)
We have presented new bathymetry data from under the Ekström Ice Shelf, Dronning Maud Land, Antarctica
The Ekström Ice Shelf cavity is currently one of the best mapped in Antarctica

Summary

Introduction

Ice shelves surrounding Antarctica act as buttresses, restraining ice discharge from the continent into the oceans, and regulating Antarctic contributions to sea level rise (Dupont & Alley, 2005). The continental shelf is narrow (Figure 1b), meaning the ice shelves of DML are in close proximity to Warm Deep Water (WDW) masses which flow along the continental slope, making this a potentially sensitive region to future change (Hattermann, 2018; Heywood et al, 2013; Thompson et al, 2018). It has been highlighted as susceptible to marine ice sheet instability (Morlighem et al, 2020; Ritz et al, 2015). They show the urgent need for more measurements of sub-ice-shelf bathymetry along the coast of this sector of Antarctica and for many other ice shelves, where the bathymetry is poorly constrained

Data and Methods

Results and Discussion

Conclusions