Because of our heavy use of fossil fuels, the amount of carbon dioxide in the atmosphere has been increasing since the industrial revolution. The destruction of forests which use carbon dioxide also contributes to the increase in carbon dioxide.
Most of the light energy from the sun is emitted in wavelengths shorter than 4,000 nanometers (.000004 meters). The heat energy released from the earth, however, is released in wavelengths longer than 4,000 nanometers. Carbon dioxide doesn't absorb the energy from the sun, but it does absorb some of the heat energy released from the earth. When a molecule of carbon dioxide absorbs heat energy, it goes into an excited unstable state. It can become stable again by releasing the energy it absorbed. Some of the released energy will go back to the earth and some will go out into space.
So in effect, carbon dioxide lets the light energy in, but doesn't let all of the heat energy out, similar to a greenhouse.
Nitrous oxide is known to have a significant global climatologic impact as a naturally occurring greenhouse gas. After carbon dioxide and methane, nitrous oxide is the third most climatologically significant greenhouse gas. Greenhouse gases act like a warming blanket in the troposphere and prevent radiative cooling. Nitrous oxide is a particularly potent greenhouse gas with 300 times the global warming potential of carbon dioxide over 100 yr, according to the Intergovernmental Panel on Climate Change.2 It seems prudent to include the climatologic effects of nitrous oxide as a biologic effect of the gas.
Nitrous oxide, in contrast, has a long atmospheric lifetime of approximately 120 yr.* The vast majority of atmospheric nitrous oxide from human activity is released from combustion and agricultural soils, particularly after the use of nitrogenous fertilizers.