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Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e

Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e
Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e

Environmental conditions during Marine Isotope Stage (MIS) 5e (130-116 ka) represent an important "process analogue"for understanding the climatic responses to present and future anthropogenic warming. The response of Antarctic sea ice to global warming is particularly uncertain due to the short length of the observational record. Reconstructing Antarctic winter sea-ice extent during MIS 5e therefore provides insights into the temporal and spatial patterns of sea-ice change under a warmer-than-present climate. This study presents new MIS 5e records from nine marine sediment cores located south of the Antarctic Polar Front between 55 and 70°S. Winter sea-ice extent and sea-surface temperatures are reconstructed using marine diatom assemblages and a modern analogue technique transfer function, and changes in these environmental variables between the three Southern Ocean sectors are investigated. The Atlantic and East Indian sector records show much more variable MIS 5e winter sea-ice extent and sea-surface temperatures than the Pacific sector records. High variability in the Atlantic sector winter sea-ice extent is attributed to high glacial meltwater flux in the Weddell Sea, indicated by increased abundances of the diatom species Eucampia antarctica and Fragilariopsis cylindrus. The high variability in the East Indian sector winter sea-ice extent is conversely believed to result from large latitudinal migrations of the flow bands of the Antarctic Circumpolar Current, inferred from latitudinal shifts in the sea-surface temperature isotherms. Overall, these findings suggest that Pacific sector winter sea ice displays a low sensitivity to warmer climates. The different variability and sensitivity of Antarctic winter sea-ice extent in the three Southern Ocean sectors during MIS 5e may have significant implications for the Southern Hemisphere climatic system under future warming.

1814-9332
129-146
Chadwick, Matthew
aaf95186-1d37-4866-8899-13abb9b7257a
Allen, Claire S.
7c197775-c25e-4555-84e3-b4621354aac0
Sime, Louise C.
27e4dd9a-2b54-4f4c-b345-31fff4a2f2b6
Crosta, Xavier
3ee8d28c-87aa-42e9-9f5e-218e81fa53f3
Hillenbrand, Claus-dieter
8dc0c76e-e79b-4c8f-90ed-07035aabab98
Chadwick, Matthew
aaf95186-1d37-4866-8899-13abb9b7257a
Allen, Claire S.
7c197775-c25e-4555-84e3-b4621354aac0
Sime, Louise C.
27e4dd9a-2b54-4f4c-b345-31fff4a2f2b6
Crosta, Xavier
3ee8d28c-87aa-42e9-9f5e-218e81fa53f3
Hillenbrand, Claus-dieter
8dc0c76e-e79b-4c8f-90ed-07035aabab98

Chadwick, Matthew, Allen, Claire S., Sime, Louise C., Crosta, Xavier and Hillenbrand, Claus-dieter (2022) Reconstructing Antarctic winter sea-ice extent during Marine Isotope Stage 5e. Climate of the Past, 18 (1), 129-146. (doi:10.5194/cp-18-129-2022).

Record type: Article

Abstract

Environmental conditions during Marine Isotope Stage (MIS) 5e (130-116 ka) represent an important "process analogue"for understanding the climatic responses to present and future anthropogenic warming. The response of Antarctic sea ice to global warming is particularly uncertain due to the short length of the observational record. Reconstructing Antarctic winter sea-ice extent during MIS 5e therefore provides insights into the temporal and spatial patterns of sea-ice change under a warmer-than-present climate. This study presents new MIS 5e records from nine marine sediment cores located south of the Antarctic Polar Front between 55 and 70°S. Winter sea-ice extent and sea-surface temperatures are reconstructed using marine diatom assemblages and a modern analogue technique transfer function, and changes in these environmental variables between the three Southern Ocean sectors are investigated. The Atlantic and East Indian sector records show much more variable MIS 5e winter sea-ice extent and sea-surface temperatures than the Pacific sector records. High variability in the Atlantic sector winter sea-ice extent is attributed to high glacial meltwater flux in the Weddell Sea, indicated by increased abundances of the diatom species Eucampia antarctica and Fragilariopsis cylindrus. The high variability in the East Indian sector winter sea-ice extent is conversely believed to result from large latitudinal migrations of the flow bands of the Antarctic Circumpolar Current, inferred from latitudinal shifts in the sea-surface temperature isotherms. Overall, these findings suggest that Pacific sector winter sea ice displays a low sensitivity to warmer climates. The different variability and sensitivity of Antarctic winter sea-ice extent in the three Southern Ocean sectors during MIS 5e may have significant implications for the Southern Hemisphere climatic system under future warming.

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Accepted/In Press date: 2 December 2021
e-pub ahead of print date: 24 January 2022
Published date: 1 March 2022

Identifiers

Local EPrints ID: 468095
URI: http://eprints.soton.ac.uk/id/eprint/468095
ISSN: 1814-9332
PURE UUID: 5a7204ce-d331-4d1c-a454-efc1b28d58c3

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Date deposited: 02 Aug 2022 17:04
Last modified: 02 Aug 2022 17:05

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Contributors

Author: Matthew Chadwick
Author: Claire S. Allen
Author: Louise C. Sime
Author: Xavier Crosta
Author: Claus-dieter Hillenbrand

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