Changes

: Once [[organism]]s [[Evolution by Natural Selection|evolved]] which could get [[energy]] from sunlight via [[photosynthesis]] the [[Carbon Dioxide]] in the '''atmosphere''' decreased and [[Oxygen]] began to increase.

: [[Carbon Dioxide]] was also removed from the '''atmosphere''' when it [[dissolve]]d in the [[ocean]] and was used by some sea [[organism]]s to form hard [[Calcium Carbonate]] shells.

===Equilibrium of the Earth's Atmosphere===