Earth may have got its oxygen from blue-green algae

According to a recent study, a whiff from blue-green algae was likely responsible for the Earth's oxygen.

Earth's oxygen-rich atmosphere emerged in whiffs from a kind of blue-green algae in shallow oceans around 2.5 billion years ago, according to the study from Canadian and US scientists.

These whiffs of oxygen likely happened in the following 100 million years, changing the levels of oxygen in Earth's atmosphere until enough accumulated to create a permanently oxygenated atmosphere around 2.4 billion years ago - a transition widely known as the Great Oxidation Event.

The onset of Earth's surface oxygenation was likely a complex process characterized by multiple whiffs of oxygen until a tipping point was crossed, said Brian Kendall of the University of Waterloo. "Until now, we haven't been able to tell whether oxygen concentrations 2.5 billion years ago were stable or not. These new data provide a much more conclusive answer to that question."

The study is published in Science Advances.