Slide 21: The greenhouse effect
To some extent, life on earth is contingent on the greenhouse effect - without it the earth's surface temperature would be considerably below the freezing point of water.
Certain gases are opaque at infra-red light frequencies. These include methane, water vapour, nitrous oxides, ozone, and most importantly, CO2.
Some short wave solar radiation is converted to long wave infra red at the earth's surface. This is then absorbed by greenhouse gases, raising the atmospheric temperature.
As the proportion of greenhouse gases in the atmosphere increases, so does the potential for absorption of radiation, effectively raising the temperature.
This effect, and the dangers of increased carbon dioxide emissions was outlined by Svante Arrhenius over a century ago! (Arrhenius, 1896).
S. Arrhenius, Phila. Mag. 41, 237 (1896).