If the atmosphere is composed of almost all nitrogen and oxygen, why are we so concerned about the small amounts of
other gasses?
Solar energy (short wave) passes through the air without much effect. When it strikes a surface, such as the ground,
it is converted to heat. That heat radiates back into the air as infrared (long wave) energy. Some gasses, such as carbon
dioxide and methane, are very effective at trapping that infrared light and converting it back into heat. When
the air is warmed as a result of gasses converting infrared radiation back into heat, the air warms. The warming of
the air is the greenhouse effect.
The atmosphere is about 78 percent nitrogen gas (N2) and about 21 percent oxygen gas (O2). The remaining
1 percent is made up of mostly argon gas (Ar), carbon dioxide (CO2), water vapor (H2O), and ozone (O3). There
are two reasons that the other gasses are a concern. First, some gasses can be toxic to living things. Excess ozone
near the surface can harm plants as can gasses like sulfur dioxide. Carbon monoxide is very poisonous to animals,
including humans. The other reason is the greenhouse effect.