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Earth's early atmosphere before life contained almost no free oxygen, and oxygen levels rose substantially only after cyanobacteria began photosynthesis, in the Great Oxidation Event roughly 2.4 billion years ago.
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INSUFFICIENT LEANING
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10 sources for · 0 against
Is it true that Earth's early atmosphere before life contained almost no free oxygen, and oxygen levels rose substantially only after cyanobacteria began photosynthesis, in the Great Oxidation Event roughly 2.4 billion years ago?
Unclear. Multiple peer-reviewed sources confirm that Earth's atmosphere shifted from anoxic to oxygenated conditions around 2.4 billion years ago in the Great Oxidation Event, and one notes oxygenic photosynthesis emerged hundreds of millions of years earlier. None directly establishes that the pre-life atmosphere contained almost no free oxygen or that cyanobacterial photosynthesis specifically drove the rise.
Verdict: PARTIAL LEAN · 10 sources for, 0 against · Last checked
Evidence for · 10
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PW, C., I, S., MA, K., J, H., LL, N., JD, H., S, W., & M, F. (2026). Revisiting the greatness of Earth's great oxidation.. doi.org. https://doi.org/10.1038/s43247-026-03518-8
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More for · 9
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Cooke, G., Marsh, D., Walsh, C., Sainsbury-Martinez, F., & Braam, M. (2026). The oxygen valve on hydrogen escape since the great oxidation event. doi.org. https://doi.org/10.5194/cp-22-483-2026
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Biogeochemical impact of nickel and urea in the great oxidation event. (n.d.). cir.nii.ac.jp. https://cir.nii.ac.jp/crid/1050023859260239232
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A POSSIBLE RELATIONSHIP BEWTEEN THE GREAT OXIDATION EVENT AND THE PALEOPROTEROZOIC SNOWBALL EARTH EVENT. (n.d.). cir.nii.ac.jp. https://doi.org/10.50968/vivaorigino.45_5
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Oceanic nickel depletion and a methanogen famine before the Great Oxidation Event. (2009). insu.hal.science. https://doi.org/10.1038/nature07858
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Long-term evolution of terrestrial weathering and its link to Earth's oxygenation. (2022). hal.science. https://doi.org/10.1016/j.epsl.2022.117490
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Jaziri, A. Y., Charnay, B., Selsis, F., Leconte, J., & Lefèvre, F. (2022). Dynamics of the Great Oxidation Event from a 3D photochemical–climate model. doi.org. https://doi.org/10.5194/cp-18-2421-2022
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Horne, J. E. & Goldblatt, C. (2024). EONS: A New Biogeochemical Model of Earth's Oxygen, Carbon, Phosphorus, and Nitrogen Systems From the Archean to the Present. doi.org. https://doi.org/10.1029/2023gc011252
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Destabilization of deep oxidized mantle drove the Great Oxidation Event. (n.d.). cir.nii.ac.jp. https://doi.org/10.1126/sciadv.abg1626
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A productivity collapse to end Earth’s Great Oxidation. (n.d.). cir.nii.ac.jp. https://doi.org/10.1073/pnas.1900325116
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