# Great Oxidation Event **Entity class:** Event or historical development **Domain:** Earth History / Evolution / Geochemistry **Doc Type:** Canonical Wiki Node **Maturity:** Developing ## Definition The **Great Oxidation Event** is the first sustained rise of free oxygen in Earth's atmosphere, beginning roughly 2.4 billion years ago, driven by oxygenic photosynthesis in cyanobacteria. Oxygen, a metabolic waste product, accumulated once geological sinks could no longer absorb it. ## Consequences Oxygen was toxic to much of the anaerobic life that had dominated the planet, and anaerobic metabolisms retreated into anoxic refuges such as sediments, deep soils and, later, the guts of animals, where they persist today. The same oxygen made aerobic respiration possible, yielding roughly an order of magnitude more energy per molecule of glucose; it built the ozone layer; and it opened the long path to complex multicellular life. ## Corpus Context [[articles/There Is Only One Rocket on the Pad|There Is Only One Rocket on the Pad]] uses the event as the oldest precedent for [[wiki/The Bloom|the Bloom]]: a single transition that was an extinction-level pressure from inside the anaerobic world and a genesis from outside it. The event was itself a microbial bloom, which is the source of the term. ## Evidence Boundary - **Established:** the rise of atmospheric oxygen roughly 2.4 to 2.1 billion years ago, recorded in sulfur isotopes and sedimentary geochemistry. - **Strongly indicated:** cyanobacterial photosynthesis as the oxygen source. - **Unresolved:** the scale of anaerobic extinction, and the delay between the origin of oxygenic photosynthesis and atmospheric accumulation, both active research questions. ## Relationships - **Precedent for:** [[wiki/The Bloom|The Bloom]] - **Class:** [[wiki/Regime Shift|Regime Shift]] · [[wiki/Major Evolutionary Transitions|Major Evolutionary Transitions]] - **Mechanism:** [[wiki/Dissipative Structure|Dissipative Structure]] ## Sources / Provenance - Holland, Heinrich D. "The Oxygenation of the Atmosphere and Oceans." *Philosophical Transactions of the Royal Society B* 361, no. 1470 (2006): 903–915. - Lyons, Timothy W., Christopher T. Reinhard, and Noah J. Planavsky. "The Rise of Oxygen in Earth's Early Ocean and Atmosphere." *Nature* 506 (2014): 307–315.