Three major greenhouse gases are carbon dioxide, methane and nitrous oxide. When these gases are released into the atmosphere and encircle the globe, they absorb some heat radiating from earth and re-radiate it downward. This is similar to the way ultraviolet radiation is reflected off the glass in a greenhouse. Most scientists, says Talbert, agree that the level of carbon dioxide emissions has increased 30 percent since 1850, the advent of the Industrial Revolution and the beginning of the fossil fuel era. In the current carbon cycle, a plant takes in CO2 and retains carbon until it dies and decomposes, then releasing CO2 back into the atmosphere.
Fossil fuel is mostly carbon, created in a carbon cycle that closed millions of years ago.
Burning it releases CO2 in excess of that required by the current carbon cycle. Carbon sequestration is the long-term storage of carbon in the soil and in living and dead vegetation. It is a way to offset carbon dioxide emissions. Therein lies the possibility of agriculture providing a valuable service to society by storing carbon that offsets the CO2 emitted by other sectors, said the scientist. If a carbon credit market was officially established, farmers, ranchers and woodlot owners could be paid for the service of storing carbon in plants and in the soil, Talbert reasons.