NASA-supported scientists have provided additional evidence that molecular oxygen appeared in Earth’s atmosphere at least 2.5 billion years ago as relatively short-lived “whiffs” prior to the oxygenation of the planet’s atmosphere.

Today, oxygen is a major component of our atmosphere and is the gas that humans and other animals breathe to stay alive. However, oxygen hasn’t always been a major part of Earth’s atmospheric composition. What is known as the Great Oxidation Event (GOE) occurred sometime between 2.4 and 2.1 billion years ago, leaving the atmosphere rich in oxygen. This was a powerful turning point in the evolution of life because large and complex organisms on Earth require oxygen to function.

In 2007, Ariel Anbar (Arizona State University) and his team first published evidence of oxygen gas in Earth’s oceans some 2.5 billion years ago. This was interpreted as evidence of a “whiff” of oxygen that predated the GOE. The findings resulted in debate within the scientific community. Now, Anbar and his team have published follow-up work that further supports the “whiff” theory. The paper also highlights the process of scientific debate and the importance of scrutinizing theories derived from data.

Click here to read a press release from Arizona State University regarding this work.

The paper, “Technical comment on “Reexamination of 2.5-Ga ‘whiff’ of oxygen interval points to anoxic ocean before GOE,”” was published in the journal Science Advances.