Abstract
How ice sheets respond to changes in their grounding line is important in understanding ice sheet vulnerability to climate and ocean changes. The interplay between regional grounding line change and potentially diverse ice flow behaviour of contributing catchments is relevant to an ice sheet’s stability and resilience to change. At the last glacial maximum, marine-based ice streams in the western Ross Sea were fed by numerous catchments draining the East Antarctic Ice Sheet. Here we present geomorphological and acoustic stratigraphic evidence of ice sheet reorganisation in the South Victoria Land (SVL) sector of the western Ross Sea. The opening of a grounding line embayment unzipped ice sheet sub-sectors, enabled an ice flow direction change and triggered enhanced flow from SVL outlet glaciers. These relatively small catchments behaved independently of regional grounding line retreat, instead driving an ice sheet readvance that delivered a significant volume of ice to the ocean and was sustained for centuries.
Highlights
How ice sheets respond to changes in their grounding line is important in understanding ice sheet vulnerability to climate and ocean changes
The majority of the East Antarctic Ice Sheet (EAIS) is grounded above sea level, approximately 19 m of sea level equivalent is stored within portions of the EAIS that rest on a bed below sea level and are susceptible to marine forcings[9]
A well-developed suite of glacial landforms is observed on the seafloor throughout the western Ross Sea (Figs. 2–5), within which distinct assemblages are identified that relate to ice flow paths and margin positions during the last deglacial period
Summary
How ice sheets respond to changes in their grounding line is important in understanding ice sheet vulnerability to climate and ocean changes. We present geomorphological and acoustic stratigraphic evidence of ice sheet reorganisation in the South Victoria Land (SVL) sector of the western Ross Sea. The opening of a grounding line embayment unzipped ice sheet sub-sectors, enabled an ice flow direction change and triggered enhanced flow from SVL outlet glaciers. Recent interpretations of seafloor glacial geomorphology[20,22], terrestrial outlet glacier ice surface histories[23] and Antarctic-wide numerical ice sheet modelling[5,24] suggest a significant role of the Southern Victoria Land (SVL) sector of the EAIS in governing, and responding to, ice sheet and ice shelf dynamics in the western Ross Sea. Fringed by the Transantarctic Mountains from the LGM grounding position to the present-day calving front, the western Ross Sea is an excellent location for examining the interplay between source outlets and regional grounding line change. These collectively raise questions of the vulnerability, stability or resilience of different ice sheet sectors to grounding line change, and demand analysis of why different sectors may behave in different ways including, in cases such as we present here, advance for a period of centuries in the face of climate warming and sea level rise
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