LetŐs begin our
examination of the carbon cycle by focusing
on emissions of CO2.
Currently, about 6.3
gigatons of carbon are released into the atmosphere as a result of fossil fuel
burning.
About 40% of this
comes from coal burning, another
40% comes from burning of oil and oil derivatives
(such as gasoline), and the remaining 20%
comes from burning of natural gas (methane).