Describe how and why Earth's atmosphere changed throughout the first 2 billion years of its existence?

Question

Describe how and why Earth's atmosphere changed throughout the first 2 billion years of its existence?

Answer 1

These links should prove useful.

Answer 2

There was far more carbon dioxide then but nobody complained.

Answer 3

Great question. In the early atmosphere carbon dioxide was the primary gas and nitrogen/oxygen was about 2% of the total atmosphere. The early atmosphere had 50 times more mass at that time and almost all of the CO2 was absorbed by calcium and magesium into calcite/dolomite formations over a few billion years. As more and more of the CO2 got absorbed into rocks the mass and pressure of the atmosphere was reduced to a point where life could thrive and evolve. As life evolved more CO2 was absorbed into coal and hydrocarbon deposits and the atmosphere lost more mass until it got to where it is now. There are lots of details that need to be discovered about the atmosphere and how it has changed over time.