From: University of Exeter
Published February 2, 2017 10:46 AM

Low level of oxygen in Earth's middle ages delayed evolution for two billion years

New research by the University of Exeter explains how oxygen was trapped at such low levels. Professor Tim Lenton and Dr Stuart Daines, of the University of Exeter Geography department, created a computer model to explain how oxygen stabilised at low levels and failed to rise any further, despite oxygen already being produced by early photosynthesis. Their research helps explain why the ‘Great Oxidation Event’, which introduced oxygen into the atmosphere around 2.4 billion years ago, did not generate modern levels of oxygen.

In their paper, published in Nature Communications, 'Atmospheric oxygen regulation at low Proterozoic levels by incomplete oxidative weathering of sedimentary organic carbon', the University of Exeter scientists explain how organic material - the dead bodies of simple lifeforms - accumulated in the earth’s sedimentary rocks. After the Great Oxidation, and once plate tectonics pushed these sediments to the surface, they reacted with oxygen in the atmosphere for the first time.

The more oxygen in the atmosphere, the faster it reacted with this organic material, creating a regulatory mechanism whereby the oxygen was consumed by the sediments at the same rate at which it is produced.

Read more at University of Exeter

Image Credits: NASA

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