This image is from the natural history museum in London .. it was during the archean era that life first arose on earth .. at this time there were no continents, just small islands in a shallow ocean .. there was a vast amount of carbon dioxide in the atmosphere, but since the sun was much fainter back then, the combined effect did not raise earth's temperature to an extreme .. such levels of carbon dioxide would be toxic to the majority of animals alive today, as would the low oxygen levels..