Great #Oxygenation #Event, which occurred around 2.4 billion years ago, was one of the biggest #transformations of our planet. Before it, there was practically no oxygen in the #atmosphere; after, there wa. Tthe rise of oxygen is sen as life triumphantly terraforming a passive planet. But we’re learning now that Earth was an active participant, and it took two more big lifts of oxygen over the succeeding #2billionyears before it reached breathable levels.

https://arstechnica.com/science/2023/05/the-complicated-history-of-how-the-earths-atmosphere-became-breathable/