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CO2drawdown following the middle Miocene expansion of the Antarctic Ice Sheet

CO2drawdown following the middle Miocene expansion of the Antarctic Ice Sheet
CO2drawdown following the middle Miocene expansion of the Antarctic Ice Sheet
The development of a permanent, stable ice sheet in East Antarctica happened during the middle Miocene, about 14 million years (Myr) ago. The middle Miocene therefore represents one of the distinct phases of rapid change in the transition from the “greenhouse” of the early Eocene to the “icehouse” of the present day. Carbonate carbon isotope records of the period immediately following the main stage of ice sheet development reveal a major perturbation in the carbon system, represented by the positive ?13C excursion known as carbon maximum 6 (“CM6”), which has traditionally been interpreted as reflecting increased burial of organic matter and atmospheric pCO2 drawdown. More recently, it has been suggested that the ?13C excursion records a negative feedback resulting from the reduction of silicate weathering and an increase in atmospheric pCO2. Here we present high-resolution multi-proxy (alkenone carbon and foraminiferal boron isotope) records of atmospheric carbon dioxide and sea surface temperature across CM6. Similar to previously published records spanning this interval, our records document a world of generally low (~300?ppm) atmospheric pCO2 at a time generally accepted to be much warmer than today. Crucially, they also reveal a pCO2 decrease with associated cooling, which demonstrates that the carbon burial hypothesis for CM6 is feasible and could have acted as a positive feedback on global cooling.
pCO2, middle Miocene, ice sheets, alkenone ?13C, boron ?11B
0883-8305
42-53
Badger, Marcus P.S.
f1bb5cb5-b886-4676-a2d2-f58a748301ff
Lear, Caroline H.
c0caf74d-ed6c-4b04-b5c8-de8fc794943c
Pancost, Richard D.
5914e19e-7777-4304-9fd8-86e2e9cfe8a1
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Bailey, Trevor R.
1584c7d5-e612-4990-9998-eb867de77cc2
Leng, Melanie J.
71755042-2b5f-44a6-8420-019f13a4a946
Abels, Hemmo A.
c7efedf0-b992-4a96-9885-72aa9d07f3eb
Badger, Marcus P.S.
f1bb5cb5-b886-4676-a2d2-f58a748301ff
Lear, Caroline H.
c0caf74d-ed6c-4b04-b5c8-de8fc794943c
Pancost, Richard D.
5914e19e-7777-4304-9fd8-86e2e9cfe8a1
Foster, Gavin L.
fbaa7255-7267-4443-a55e-e2a791213022
Bailey, Trevor R.
1584c7d5-e612-4990-9998-eb867de77cc2
Leng, Melanie J.
71755042-2b5f-44a6-8420-019f13a4a946
Abels, Hemmo A.
c7efedf0-b992-4a96-9885-72aa9d07f3eb

Badger, Marcus P.S., Lear, Caroline H., Pancost, Richard D., Foster, Gavin L., Bailey, Trevor R., Leng, Melanie J. and Abels, Hemmo A. (2013) CO2drawdown following the middle Miocene expansion of the Antarctic Ice Sheet. Paleoceanography, 28 (1), 42-53. (doi:10.1002/palo.20015).

Record type: Article

Abstract

The development of a permanent, stable ice sheet in East Antarctica happened during the middle Miocene, about 14 million years (Myr) ago. The middle Miocene therefore represents one of the distinct phases of rapid change in the transition from the “greenhouse” of the early Eocene to the “icehouse” of the present day. Carbonate carbon isotope records of the period immediately following the main stage of ice sheet development reveal a major perturbation in the carbon system, represented by the positive ?13C excursion known as carbon maximum 6 (“CM6”), which has traditionally been interpreted as reflecting increased burial of organic matter and atmospheric pCO2 drawdown. More recently, it has been suggested that the ?13C excursion records a negative feedback resulting from the reduction of silicate weathering and an increase in atmospheric pCO2. Here we present high-resolution multi-proxy (alkenone carbon and foraminiferal boron isotope) records of atmospheric carbon dioxide and sea surface temperature across CM6. Similar to previously published records spanning this interval, our records document a world of generally low (~300?ppm) atmospheric pCO2 at a time generally accepted to be much warmer than today. Crucially, they also reveal a pCO2 decrease with associated cooling, which demonstrates that the carbon burial hypothesis for CM6 is feasible and could have acted as a positive feedback on global cooling.

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More information

Published date: March 2013
Keywords: pCO2, middle Miocene, ice sheets, alkenone ?13C, boron ?11B
Organisations: Geochemistry

Identifiers

Local EPrints ID: 356549
URI: https://eprints.soton.ac.uk/id/eprint/356549
ISSN: 0883-8305
PURE UUID: 1aeb51ee-53c7-4ce8-a128-502eb5bc4c16

Catalogue record

Date deposited: 06 Sep 2013 15:13
Last modified: 18 Jul 2017 03:38

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