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

Yuzhen Yan; Edward J Brook; Andrei V Kurbatov; Jeffrey P Severinghaus; John A Higgins

doi:10.1126/sciadv.abj9341

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

Sci Adv. 2021 Dec 17;7(51):eabj9341. doi: 10.1126/sciadv.abj9341. Epub 2021 Dec 15.

Authors

Yuzhen Yan^{1

2}, Edward J Brook³, Andrei V Kurbatov⁴, Jeffrey P Severinghaus⁵, John A Higgins¹

Affiliations

¹ Department of Geosciences, Princeton University, Princeton, NJ, USA.
² Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA.
³ College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
⁴ Climate Change Institute, University of Maine, Orono, ME, USA.
⁵ Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA.

Abstract

The history of atmospheric oxygen (PO₂) 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 PO₂ 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 PO₂ between samples at 1.5 Ma and 810 thousand years (ka), suggesting that the Late-Pleistocene imbalance in O₂ 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 CO₂ over the past ~1 Ma requires negative feedback mechanisms such as Pco₂-dependent silicate weathering. Fast processes must also act to suppress the immediate Pco₂ increase because of the imbalance in O₂ sinks over sources beginning in the Mid-Pleistocene.