Pine Island Glacier Ice-Shelf (PIGIS) has been thinning rapidly over recent decades, resulting in a progressive drawdown of the inland ice and an upstream migration of the grounding line. The resultant ice loss from Pine Island Glacier (PIG) and its neighboring ice streams presently contributes an estimated 10% to global sea-level rise, motivating efforts to constrain better the rate of future ice retreat. One route towards gaining a better understanding of the processes required to underpin physically-based projections is provided by examining assemblages of landforms and sediment exposed over recent decades by the ongoing ungrounding of PIG. Here we present high-resolution bathymetry and sub-bottom-profiler data acquired by autonomous underwater vehicle (AUV) surveys beneath PIGIS in 2009 and 2014 respectively. We identify landforms and sediments associated with grounded-ice flow, proglacial and subglacial sediment transport, overprinting of lightly-grounded ice-shelf keels and stepwise grounding-line retreat. The location of a submarine ridge (Jenkins Ridge) coincides with a transition from exposed crystalline bedrock to abundant sediment cover potentially linked to a thick sedimentary basin extending upstream of the modern grounding line. The capability of acquiring high-resolution data from AUV platforms enable observations of landforms and understanding of processes on a scale that is not possible in standard offshore geophysical surveys.
Bibliographical noteThis work was supported by funding from the UK Natural Environment Research Council (NERC) iSTAR Programme Grants NE/J005665/2 and NE/J005770/1 and NERC Grant NE/G001367/1. DD was supported by NERC Training Grant NE/K011189/1. FON was supported by NSF grant ANT-838735. MS was supported by NERC Grant NE/J004766/1. AJ We thank the Autosub technical teams led by Steve McPhail and the Captain and cruise participants of RRS James Clark Ross cruise JR294/295 and RVIB Nathaniel B Palmer cruise NBP09-01 for conducting the AUV operations. We thank Julian Dowdeswell and two anonymous reviewers for constructive reviews which improved the clarity of the manuscript. Data used in this article can be obtained from the UK Polar Data Centre.
- Pine Island Glacier
- West Antarctic Ice Sheet
- autonomous underwater vehicle
- ice sheet dynamics
- marine geophysics