Oxygen Oasis Discovered in Antarctic Lake

A little oxygenated slice of paradise survives deep in an icy Antarctic lake, providing a window into what life on Earth may have been like before oxygen permeated the atmosphere. Earth's atmosphere was relatively oxygen-free until about 2.4 billion years ago, when photosynthetic bacteria started pumping out oxygen as a waste product in the process of transforming sunlight into energy. This "Great Oxidation Event" reflects the point at which oxygen became widespread, but researchers now think ph