How can minor atmospheric gases have such a large impact on climate?
The major gases, nitrogen (N2), oxygen (O2), and argon (Ar), which together comprise about 99.8% of the atmosphere, do not absorb visible light, nor infrared light. If the atmosphere contained only those three gases, the radiation would go right through without any effect on the heating of the atmosphere or surface. That leaves it to the minor gases such as water vapor, carbon dioxide, methane, nitrous oxide, ozone, and others to absorb infrared light. The total mass of the atmosphere is very large, about 5 x 1021 grams, or 5 million times a billion metric ton. The amounts of the minor gases are therefore still very large, sufficient to cause the absorption of a major fraction of infrared light in the atmosphere.
