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Published February 22, 2021 | Supplemental Material + Published
Journal Article Open

High Organic Burial Efficiency Is Required to Explain Mass Balance in Earth's Early Carbon Cycle

Abstract

Earth's carbon cycle maintains a stable climate and biosphere on geological timescales. Feedbacks regulate the size of the surface carbon reservoir, and on million‐year timescales the carbon cycle must be in steady state. A major question about the early Earth is whether carbon was cycled through the surface reservoir more quickly or slowly than it is today. The answer to this question holds important implications for Earth's climate state, the size of the biosphere through time, and the expression of atmospheric biosignatures on Earth‐like planets. Here, we examine total carbon inputs and outputs from the Earth's surface over time. We find stark disagreement between the canonical histories of carbon outgassing and carbon burial, with the former implying high rates of throughput on the early Earth and the latter suggesting sluggish carbon cycling. We consider solutions to this apparent paradox and conclude that the most likely resolution is that high organic burial efficiency in the Precambrian enabled substantial carbon burial despite limited biological productivity. We then consider this model in terms of Archean redox balance and find that in order to maintain atmospheric anoxia prior to the Great Oxidation Event, high burial efficiency likely needed to be accompanied by greater outgassing of reductants. Similar mechanisms likely govern carbon burial and redox balance on terrestrial exoplanets, suggesting that outgassing rates and the redox state of volcanic gases likely play a critical role in setting the tempo of planetary oxygenation.

Additional Information

© 2020. American Geophysical Union. Issue Online: 22 February 2021; Version of Record online: 22 February 2021; Accepted manuscript online: 25 December 2020; Manuscript accepted: 17 December 2020; Manuscript revised: 14 December 2020; Manuscript received: 16 June 2020. The authors thank Cin‐Ty Lee and Katsumi Matsumoto for helpful comments in the review and editorial handling of this manuscript. M. Kipp acknowledges funding from an NSF Graduate Research Fellowship and an Agouron Institute Geobiology Postdoctoral Fellowship. J. Krissansen‐Totton was supported by NASA through the NASA Hubble Fellowship grant HF2‐51437 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. for NASA under contract NAS5‐26555. David C. Catling acknowledges funding from NSF Frontiers in Earth System Dynamics award 1338810 and NASA Exobiology Program grant NNX15AL23G. Data Availability Statement: No new data were presented in this study. All compiled data are presented in the included figures and tables with accompanying references. All model equations are presented in the main text.

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Supplemental Material - 2020gb006707-sup-0001-supporting_information_si-s01.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023