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).