Existing and potential evidence for Holocene grounding-line retreat and readvance in Antarctica

Johnson, Joanne S., Venturelli, Ryan A., Balco, Greg, Allen, Claire S., Braddock, Scott, Campbell, Seth, Goehring, Brent M., Hall, Brenda L., Neff, Peter D., Nichols, Keir A., Rood, Dylan H., Thomas, Elizabeth R. and Woodward, John (2021) Existing and potential evidence for Holocene grounding-line retreat and readvance in Antarctica. Cryosphere Discussions. p. 360. ISSN 1994-0432 (In Press)

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Official URL: https://doi.org/10.5194/tc-2021-360

Abstract

Widespread existing geological records from above the modern ice-sheet surface and outboard of the current ice margin show that the Antarctic Ice Sheet (AIS) was much more extensive at the Last Glacial Maximum (~20 ka) than at present. However, whether it was ever smaller than present during the last few millennia, and (if so) by how much, is known only for a few locations because direct evidence lies within or beneath the ice sheet, which is challenging to access. Here, we describe how retreat and readvance (henceforth “readvance”) of AIS grounding lines during the Holocene could be detected and quantified using subglacial bedrock, subglacial sediments, marine sediment cores, relative sea-level (RSL) records, radar data, and ice cores. Of these, only subglacial bedrock and subglacial sediments can provide direct evidence for readvance. Marine archives are of limited utility because readvance commonly covers evidence of earlier retreat. Nevertheless, stratigraphic transitions documenting change in environment may provide support for direct evidence from subglacial records, as can the presence of transgressions in RSL records. With independent age control, past changes in ice structure and flow patterns revealed by radar can be used to infer ice volume changes commensurate with readvance. Since ice cores capture changes in surface mass balance, elevation, and changes in atmospheric and oceanic circulation that are known to drive grounding-line migration, they also have potential for identifying readvance. A multidisciplinary approach is likely to provide the strongest evidence for or against a smaller-than-present AIS in the Holocene.

Item Type: Article
Additional Information: Funding information: The authors are grateful for many insightful conversations with the following colleagues that helped formulate the ideas presented here: Robert Ackert (Harvard University), Alex Brisbourne, Claus-Dieter Hillenbrand, Kelly Hogan, Rob Larter, and James Smith (British Antarctic Survey), Chloe Gustafson (Scripps Institute of Oceanography), Ruthie Halberstadt (University of Massachusetts Amherst), Pippa Whitehouse (Durham University), David Pollard (Penn State University), Martin Siegert (Imperial College London). Thank you also to Kate Winter (Northumbria University) who helped prepare Fig. 6. This work is from the Geological History Constraints project, a component of the International Thwaites Glacier Collaboration (ITGC). Support from National Science Foundation (NSF: Grant OPP-1738989) and Natural Environment Research Council (NERC: Grants NE/S006710/1, NE/S00663X/1 and NE/S006753/1). SC is also supported by National Science Foundation Antarctic Earth Sciences Grant 17449949. ITGC Contribution No. 060.
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: John Coen
Date Deposited: 21 Dec 2021 10:21
Last Modified: 21 Dec 2021 10:30
URI: http://nrl.northumbria.ac.uk/id/eprint/48031

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