A Pleistocene ice core record of atmospheric O 2 concentrations

The history of atmospheric O 2 partial pressures ( P o 2 ) is inextricably linked to the coevolution of life and Earth’s biogeochemical cycles. Reconstructions of past P o 2 rely on models and proxies but often markedly disagree. We present a record of P o 2 reconstructed using O 2 /N 2 ratios from...

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Bibliographic Details
Published in:Science
Main Authors: Stolper, D. A., Bender, M. L., Dreyfus, G. B., Yan, Y., Higgins, J. A.
Other Authors: National Science Foundation
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 2016
Subjects:
ice core
Online Access:http://dx.doi.org/10.1126/science.aaf5445
https://www.science.org/doi/pdf/10.1126/science.aaf5445
Description
Summary:The history of atmospheric O 2 partial pressures ( P o 2 ) is inextricably linked to the coevolution of life and Earth’s biogeochemical cycles. Reconstructions of past P o 2 rely on models and proxies but often markedly disagree. We present a record of P o 2 reconstructed using O 2 /N 2 ratios from ancient air trapped in ice. This record indicates that P o 2 declined by 7 per mil (0.7%) over the past 800,000 years, requiring that O 2 sinks were ~2% larger than sources. This decline is consistent with changes in burial and weathering fluxes of organic carbon and pyrite driven by either Neogene cooling or increasing Pleistocene erosion rates. The 800,000-year record of steady average carbon dioxide partial pressures ( P co 2 ) but declining P o 2 provides distinctive evidence that a silicate weathering feedback stabilizes P co 2 on million-year time scales.

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