Ice core evidence for atmospheric oxygen decline since the Mid-Pleistocene transition

The history of atmospheric oxygen (PO(2)) and the processes that act to regulate it remain enigmatic because of difficulties in quantitative reconstructions using indirect proxies. Here, we extend the ice-core record of PO(2) using 1.5-million-year-old (Ma) discontinuous ice samples drilled from All...

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Bibliographic Details
Published in:Science Advances
Main Authors: Yan, Yuzhen, Brook, Edward J., Kurbatov, Andrei V., Severinghaus, Jeffrey P., Higgins, John A.
Format: Text
Language:English
Published: American Association for the Advancement of Science 2021
Subjects:
Earth
Environmental
Ecological
and Space Sciences
Allan Hills
East Antarctica
Antarc*
Antarctica
ice core
Online Access:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8673763/
http://www.ncbi.nlm.nih.gov/pubmed/34910502
https://doi.org/10.1126/sciadv.abj9341
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Summary:The history of atmospheric oxygen (PO(2)) and the processes that act to regulate it remain enigmatic because of difficulties in quantitative reconstructions using indirect proxies. Here, we extend the ice-core record of PO(2) using 1.5-million-year-old (Ma) discontinuous ice samples drilled from Allan Hills Blue Ice Area, East Antarctica. No statistically significant difference exists in PO(2) between samples at 1.5 Ma and 810 thousand years (ka), suggesting that the Late-Pleistocene imbalance in O(2) sources and sinks began around the time of the transition from 40- to 100-ka glacial cycles in the Mid-Pleistocene between ~1.2 Ma and 700 ka. The absence of a coeval secular increase in atmospheric CO(2) over the past ~1 Ma requires negative feedback mechanisms such as Pco(2)-dependent silicate weathering. Fast processes must also act to suppress the immediate Pco(2) increase because of the imbalance in O(2) sinks over sources beginning in the Mid-Pleistocene.

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