The Continuing Puzzle of the Great Oxidation Event

Alex L. Sessions*, David M. Doughty, Paula V. Welander, Roger E. Summons, Dianne K. Newman

*Corresponding author for this work

    Research output: Contribution to journalReview articlepeer-review

    146 Citations (Scopus)


    The rise of atmospheric O2 was a milestone in the history of life. Although O2 itself is not a climate-active gas, its appearance would have removed a methane greenhouse present on the early Earth and potentially led to dramatic cooling. Moreover, by fundamentally altering the biogeochemical cycles of C, N, S and Fe, its rise first in the atmosphere and later in the oceans would also have had important indirect effects on Earth's climate. Here, we summarize major lines of evidence from the geological literature that pertain to when and how O2 first appeared in significant amounts in the atmosphere. On the early Earth, atmospheric O2 would initially have been very low, probably <10-5 of the present atmospheric level. Around 2.45 billion years ago, atmospheric O2 rose suddenly in what is now termed the Great Oxidation Event. While the rise of oxygen has been the subject of considerable attention by Earth scientists, several important aspects of this problem remain unresolved. Our goal in this review is to provide a short summary of the current state of the field, and make the case that future progress towards solving the riddle of oxygen will benefit greatly from the involvement of molecular biologists.

    Original languageEnglish
    JournalCurrent Biology
    Issue number14
    Publication statusPublished - 28 Jul 2009


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