The Earth’s Early Atmosphere

Theories on the development of Earth’s atmosphere have changed and developed over the years as science has progressed.

Evidence for the early atmosphere is not enough because the Earth formed approximately 4.6 billion years ago. Scientists do not know the accurate composition of the Earth’s early atmosphere because it was too long ago.

One theory suggests that the Earth’s early atmosphere was intense volcanic activity. The surface of the Earth was covered by volcanoes that released gases that formed the Earth’s early atmosphere. Earth’s early atmosphere was very similar to the atmospheres of Mars and Venus today.

Earth's early atmospheres have a large amount of carbon dioxide with little or no oxygen gas.

As the earth cooled, water vapour condensed to form the oceans.

When the oceans formed, most of the carbon dioxide was taken out of the atmosphere by being dissolved into the oceans.

Carbonate compounds were then precipitated as sedimentary rocks, reducing the amount of carbon dioxide in the atmosphere.

The evolution of green plants and Algae helped to decrease the amount of carbon dioxide in the atmosphere by photosynthesis.

Compared with the percentage of carbon dioxide in the Earth’s early atmosphere there is not much carbon dioxide in the Earth’s atmosphere today because it has been absorbed by green plants or used for photosynthesis.

The percentage of argon in the Earth’s atmosphere today is the same as it was in the Earth’s early atmosphere because argon is unreactive.