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Evolution of the early Antarctic ice ages

Evolution of the early Antarctic ice ages
Evolution of the early Antarctic ice ages
Understanding the stability of the early Antarctic ice cap in the geological past is of societal interest because present-day atmospheric CO2 concentrations have reached values comparable to those estimated for the Oligocene and the Early Miocene epochs. Here we analyze a new high-resolution deep-sea oxygen isotope (δ18O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ∼110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ∼85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ∼110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (∼28.0 My to ∼26.3 My ago) and across the Oligocene−Miocene Transition (∼23.0 My ago). However, the high-amplitude glacial−interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical—indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions.
0027-8424
3867–3872
Liebrand, Diederik
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De Bakker, Anouk T. M.
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Beddow, Helen M.
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Wilson, Paul A.
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Bohaty, Steven M.
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Ruessink, Gerben
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Pälike, Heiko
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Batenburg, Sietske J.
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Hilgen, Frederik J.
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Hodell, David A.
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Huck, Claire E.
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Kroon, Dick
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Raffi, Isabella
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Saes, Mischa J. M.
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Van Dijk, Arnold E.
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Lourens, Lucas J.
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Liebrand, Diederik
e89fd857-7eef-4d88-b9ed-7c2931ee65e7
De Bakker, Anouk T. M.
c4682859-835b-4587-8bf0-16ccb5a25f9f
Beddow, Helen M.
7d12eaf5-0759-4ec6-b051-f0e23699a2d0
Wilson, Paul A.
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Bohaty, Steven M.
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Ruessink, Gerben
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Pälike, Heiko
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Batenburg, Sietske J.
5f05bc69-6654-4673-8279-30e5ae762726
Hilgen, Frederik J.
afa55c8c-67ff-47c9-b1c7-d1f50cc2e253
Hodell, David A.
c9977ae9-d52c-4d74-8f01-08391ec61066
Huck, Claire E.
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Kroon, Dick
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Raffi, Isabella
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Saes, Mischa J. M.
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Van Dijk, Arnold E.
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Lourens, Lucas J.
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Liebrand, Diederik, De Bakker, Anouk T. M., Beddow, Helen M., Wilson, Paul A., Bohaty, Steven M., Ruessink, Gerben, Pälike, Heiko, Batenburg, Sietske J., Hilgen, Frederik J., Hodell, David A., Huck, Claire E., Kroon, Dick, Raffi, Isabella, Saes, Mischa J. M., Van Dijk, Arnold E. and Lourens, Lucas J. (2017) Evolution of the early Antarctic ice ages. Proceedings of the National Academy of Sciences of the United States of America, 114 (15), 3867–3872. (doi:10.1073/pnas.1615440114).

Record type: Article

Abstract

Understanding the stability of the early Antarctic ice cap in the geological past is of societal interest because present-day atmospheric CO2 concentrations have reached values comparable to those estimated for the Oligocene and the Early Miocene epochs. Here we analyze a new high-resolution deep-sea oxygen isotope (δ18O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ∼110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ∼85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ∼110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (∼28.0 My to ∼26.3 My ago) and across the Oligocene−Miocene Transition (∼23.0 My ago). However, the high-amplitude glacial−interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical—indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions.

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Accepted/In Press date: 24 February 2017
e-pub ahead of print date: 27 March 2017
Published date: 11 April 2017
Organisations: Ocean and Earth Science, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 407181
URI: http://eprints.soton.ac.uk/id/eprint/407181
ISSN: 0027-8424
PURE UUID: 827f47a6-936e-4676-b17a-6c69f21cc46d
ORCID for Paul A. Wilson: ORCID iD orcid.org/0000-0001-6425-8906
ORCID for Steven M. Bohaty: ORCID iD orcid.org/0000-0002-1193-7398

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Date deposited: 01 Apr 2017 01:04
Last modified: 31 May 2022 01:36

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Contributors

Author: Diederik Liebrand
Author: Anouk T. M. De Bakker
Author: Helen M. Beddow
Author: Paul A. Wilson ORCID iD
Author: Gerben Ruessink
Author: Heiko Pälike
Author: Sietske J. Batenburg
Author: Frederik J. Hilgen
Author: David A. Hodell
Author: Claire E. Huck
Author: Dick Kroon
Author: Isabella Raffi
Author: Mischa J. M. Saes
Author: Arnold E. Van Dijk
Author: Lucas J. Lourens

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