Common Misconceptions

⚠️ Common Misconceptions

Misconception 1: "Oxygen has always been in Earth's atmosphere"

Completely wrong. For the first billion years of Earth's existence, there was virtually no free oxygen in the atmosphere. Oxygen only began to accumulate around 2.5 billion years ago as cyanobacteria evolved and began photosynthesising. If early Earth had the same atmosphere as today, the first life could not have evolved — early organisms were anaerobic and oxygen was actually toxic to them.

Misconception 2: "The early atmosphere was mainly nitrogen like today"

Wrong — Earth's early atmosphere was mainly carbon dioxide (like Venus and Mars today), with some water vapour, methane, and ammonia. Nitrogen accumulated gradually over billions of years. The current 78% nitrogen atmosphere is the result of billions of years of atmospheric processing.

Misconception 3: "CO₂ is a trace gas so it doesn't matter"

Although CO₂ is only 0.04% of the atmosphere, it has a disproportionate effect on temperature because it is a powerful greenhouse gas. Even small increases in CO₂ concentration significantly enhance the greenhouse effect. From 280 ppm (pre-industrial) to 420 ppm today — a 50% increase — is already causing measurable global warming.