CO₂ drawdown following the middle Miocene expansion of the Antarctic Ice Sheet

Badger, Marcus P.S.; Lear, Caroline H.; Pancost, Richard D.; Foster, Gavin L.; Bailey, Trevor R.; Leng, Melanie J. and Abels, Hemmo A. (2013). CO₂ drawdown following the middle Miocene expansion of the Antarctic Ice Sheet. Paleoceanography, 28(1) pp. 42–53.

DOI: https://doi.org/10.1002/palo.20015

URL: http://dx.doi.org/10.1002/palo.20015

Abstract

The development of a permanent, stable ice sheet in East Antarctica happened during the middle Miocene, about 14 Myr (million years) 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 δ¹³C 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 δ¹³C 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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• Item ORO ID
• 45568
• Item Type
• Journal Item
• ISSN
• 0883-8305
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Not Set	NE/D008654/1	NERC (Natural Environment Research Council)
  Not Set	NE/D010241/1	NERC (Natural Environment Research Council)
  Not Set	Not Set	National Museum, Wales

• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Depositing User
• Marcus Badger