Additionaly,naturally occuring forest fires release CO2 when the vegitation is burned.The disturbance caused by this change is followed by a longer term uptake of CO2 by regrowth of vegitation lasting years to decades after the fire.
Atmospheric concentrations of CO2 have increased by nearly 25% over the past 20 years, this is due to the fact that CO2 isnt chemically active and therefore emissions either accumulate in the atmosphere or are taken up by the oceans or by terrestrial biosphere (vegetation and/or soil).
One of the major contributers to CO2 emissions (80% of the annual emission from the Earth to the atmosphere) is the burning of fossil fuels.
Fossil fuels include coal, oil, and natural gas. People burn fossil fuels, as well as fresh vegetation, to release the energy stored in them. The energy is used for heat, operating automobiles, etc. The chemical process of burning fuel (known as combustion) is the same as respiration and decomposition:6 O2 + C6H12O6 ------> 6 H2O + 6 CO2.
Savana fires and vegetation/soils from tropical deforestation are also causes of CO2 emissions
Author: Julia Allbutt, document modification date: 29th May 2003