5. Role of Vegetation in Reducing CO₂

There are four principal reservoirs of regions of the earth through which carbon flows systematically: the atmosphere, the terrestrial biosphere, the oceans, and the geosphere, which include all forms of fossil. Carbon can be transferred between reservoirs and forms a network called the carbon cycle. The burning of fossil fuel, for example, currently generates an amount of CO₂ equivalent to 5 gigatons (10¹⁵ g = 1 Gt) of carbon annually. This carbon represents an additional transfer from the geosphere to the atmosphere relative to the balanced natural exchange of about 100 Gt C annually between the atmosphere and each of the remaining major carbon reservoirs resulting in a net increase of CO₂ concentration in the atmosphere (Blasing TJ. Background: carbon cycle, climate and vegetation response. In: White MR (ed) Characterization of information requirements for studies of CO₂ effects: water resources, agricultures, fisheries, forests and human health. United States Department of Energy, Washington, DC, 1985). Similarly, when a forest absorbs CO₂, deforestation, especially when the forest is burnt, adds considerable quantities of CO₂ to the atmosphere. CO₂ is also released when the forest vegetation decays and through the drowning forest. For example, a single dam, reservoir of the Balbina dam in the Brazilian Amazon, will yield as much CO₂ as would be produced by a coal-fired plant with a similar generating capacity operating for 100 years (Anon. Rainforest destruction: causes effects and false solutions. World Rainforest Movement, Malaysia, Jutaprint, 1991).