Study Suggests Earth's Slowing Rotation Led to More Oxygen in Atmosphere

A new study suggests Earth’s supply of oxygen developed thanks to the planet’s gradually slowing rotation creating longer days that allowed a certain form of algae to admit more oxygen as a byproduct of its metabolic process.

The study, published Monday in the scientific journal Nature Geoscience, suggests that about 2.4 billion years ago there was so little oxygen in Earth's atmosphere, it could barely be measured, so no animal or plant life as we know it could exist. Much of the life on Earth consisted of tiny microbes, among them, a blue-green form of algae called cyanobacteria, which breathed in carbon dioxide and exhaled oxygen in the earliest form of photosynthesis. The researchers say about 400 million years ago, the Earth took a relatively enormous leap in the amount of oxygen in its atmosphere, growing from nearly imperceptible levels to one-tenth the amount of oxygen it has now.