Earth, it now unfolds, had substantial levels of oxygen about 600 million years before the so-called Great Oxidation Event.
Earth, it now unfolds, had substantial levels of oxygen about 600 million years earlier than thought.
Findings published this week in Nature suggest that Earth’s atmosphere was already somewhat oxygenated, if not quite oxygen rich, about 3 billion years ago. That revises previous timelines of our planet, which had put the first rumblings of oxygenation about 2.3 billion years ago, at the beginning of what is known as the Great Oxidation Event.
“Instead of a simple two-stage Early Earth model with anoxic atmosphere prior to 2.4 billion years ago and oxic conditions ever after, we had at least 600 million years long transition phase,” says Michael Bau, a geoscience professor at Jacobs University, in Germany, and an author on the paper.
The tale of Earth’s oxidization is often told like this: For the first 2 billion years of Earth’s existence, the mottled, volcano-pocked planet had little oxygen – about 0.00001 percent of current levels. But about 2.3 billion years ago, there was a dramatic change. In what was perhaps the happiest moment in Earth’s existence, photosynthesizing bacteria enjoying the sunlight began, in an unusually productive feat for sunbathers, to process it into oxygen.