Earth's breathable atmosphere tied to plate tectonics?
Friday, June 20, 2014 - 07:30
in Earth & Climate
The rise of oxygen is one of the biggest puzzle in Earth's history. Our planet's atmosphere started out oxygen-free. Then, around 3.5 billion years ago, tiny microbes called cyanobacteria (or blue-green algae) learned out to carry out photosynthesis. They began using energy from sunlight to make their food from carbon dioxide and water, giving off oxygen as waste.