What is the Origin of Air?
The origin of air as we know it begins with the Oxygen Catastrophe, also known as the Great Oxidation, which occurred about 2.7 billion years ago. Prior to this, the level of oxygen in the air was approximately 1/50th of a percent. This is similar to the level of oxygen present in the atmosphere of Mars, about 1/5th of a percent. Like modern-day Mars, the atmosphere of early Earth was primarily carbon dioxide. Today, the atmosphere contains 20% oxygen, and only 0.038% carbon dioxide, making the air thoroughly breathable for oxygen-dependent organisms such as ourselves. With the advent of oxyphotosynthesis in microorganisms, this carbon dioxide was progressively consumed, creating the “waste product” of elemental oxygen. The Oxygen Catastrophe is clearly demarcated in the geological record by the introduction of large amounts of oxygenated iron (rust). These relics are called banded iron formations. The event is called a “catastrophe” because oxygen is toxic to anaerobic organisms, whic
