The carbon cycle is an essential part of life on Earth. About half the dry weight of most living organisms is carbon.[citation needed] It plays an important role in the structure, biochemistry, and nutrition of all living cells. Living biomass holds about 550 gigatons of carbon,[1] most of which is made of terrestrial plants (wood), while some 1,200 gigatons of carbon are stored in the terrestrial biosphere as dead biomass.[2]
Carbon is cycled through the terrestrial biosphere with varying speeds, depending on what form it is stored in and under which circumstances.[3] It is exchanged most quickly with the atmosphere, although small amounts of carbon leave the terrestrial biosphere and enter the oceans as dissolved organic carbon (DOC).
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- ^ Falkowski P, Scholes RJ, Boyle E, Canadell J, Canfield D, Elser J, Gruber N, Hibbard K, Högberg P, Linder S, Mackenzie FT, Moore B, Pedersen T, Rosenthal Y, Seitzinger S, Smetacek V, Steffen W (October 2000). "The global carbon cycle: a test of our knowledge of earth as a system". Science. 290 (5490): 291–6. Bibcode:2000Sci...290..291F. doi:10.1126/science.290.5490.291. PMID 11030643.
- ^ Prentice, I.C. (2001). "The carbon cycle and atmospheric carbon dioxide". Climate change 2001: the scientific basis: contribution of Working Group I to the Third Assessment Report of the Intergouvernmental Panel on Climate Change / Houghton, J.T. [edit.] Retrieved 31 May 2012.