Carbon sequestration is the uptake and storage of carbon dioxide from the atmosphere by carbon ‘sinks’. Approximately half the mass of a tree is carbon, making forests terrestrial carbon sinks. Forest vegetation absorb atmospheric CO2 and lock the carbon in their tissues while they are growing, retaining it in their biomass. Soil organic matter, derived from dead plant and animal material, is also an important store of carbon. A variable portion of this stocked carbon is, however, released if the forest vegetation is cut down and if soils are disturbed. Forest clearance is, in fact, responsible for 20% of the global carbon dioxide emissions, more than the combined global emissions of cars, boats and planes.