According to new research from Canadian and US scientists revealed that a burst of Oxygen production by photosynthetic cyanobacteria temporarily increased Oxygen concentrations in Earth’s atmosphere and shallow oceans roughly 2.5 billion years ago. It means, whiffs from blue-green algae was likely responsible for the Earth’s oxygen.

The new data suggest that these whiffs of oxygen likely happened in the following 100 million years, changing the levels of oxygen in Earth’s atmosphere until enough oxygen finally 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 O2 until a tipping point was crossed,” said Brian Kendall, a professor of Earth and Environmental Sciences at 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.”

“We are tracking atmospheric changes through time to understand how oxygen increased to the level needed to support complex life,” says Rob Creaser, professor of earth and atmospheric sciences at the University of Alberta. “When the Earth first formed, there was no oxygen in the atmosphere. Our analytical facilities here at the U of A allowed us to conduct precise analyses of this rock sample to understand the tempo at which that oxygen built up through photosynthesis.

The findings are presented in a paper published this month in Science Advances from researchers at Waterloo, University of Alberta, Arizona State University, University of California Riverside, and Georgia Institute of Technology. This new study is a follow up to work published in 2007 by the same group indicating that a small amount of O2 was present on Earth’s surface 2.5 billion years ago.