<img src=”https://naked-science.ru/wp-content/uploads/2025/03/volcanic-eruptions-oxygen-early-earth-atmosphere-1600.jpg” alt=”Ancient volcanoes likely laid the foundation for an oxygen-rich atmosphere”/>The atmosphere contains approximately 21 percent oxygen, without which life on our planet is impossible. However, billions of years ago, oxygen was practically absent there — the main component was carbon dioxide. Scientists have long been trying to understand how exactly the oxygen layer arose, which gave impetus to the development of complex organisms. Researchers from Japan came to the conclusion that large-scale volcanic activity played an important role, launching a chain of events that created the necessary conditions for the appearance of oxygen.