Scientists have now dated the 'Great Oxidation Event' to just before the planet's first 'snowball' period.
Earth's thermostat can fail spectacularly at times. Around 700 million years ago, huge volcanic eruptions triggered "Snowball Earth".
Is this where it all began?
Glaciers once covered most of Earth's surface and reflected the sun's heat back into space.
More evidence that planet Earth has gone through various frozen phases.