Carbon cycle

:See CNO cycle for the thermonuclear reaction involving carbon that helps power stars.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere, geosphere, hydrosphere and atmosphere of the Earth. (Other bodies may have carbon cycles, but little is known about them.)

Related Topics:
Biogeochemical cycle - Carbon - Biosphere - Geosphere - Hydrosphere - Atmosphere - Earth

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

All of these components are reservoirs of carbon. The cycle is usually thought of as four main reservoirs of carbon interconnected by pathways of exchange. The reservoirs are the atmosphere, terrestrial biosphere (usually includes freshwater systems), oceans, and sediments (includes fossil fuels). The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest pool of carbon near the surface of the Earth, but most of that pool is not involved with rapid exchange with the atmosphere.

Related Topics:
Ocean - Sediment - Fossil fuel

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The global carbon budget is the balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere - biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for carbon dioxide.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~