Figure 1. Increase in the CO 2 and methane concentrations in the atmosphere and the amounts of carbon cycled annually between atmosphere and oceans as well as continents. (a) Increase of CO 2 in ppm (parts per million) between 1979 and 2008. (b) Increase of methane in ppb (parts per billion) between 1984 and 2008. The zigzag fluctuations of the curves reflect seasonal variations. (c) The carbon cycle above the continents and above the oceans. Data in gigatons (Gt) of carbon. Total carbon in the atmosphere is given; all other data show annual fluxes. (Sources: NOAA, National Oceanic and Atmospheric Administration; SIO, Scripps Institution of Oceanography; G.A. Olah, A. Goeppert and G.K.S. Prakash: Beyond Oil and Gas: The Methanol Economy, Wiley-VCH Verlag GmbH [2006]; R.A. Houghton: Balancing the global carbon budget, Annu. Rev. Earth. Planet Sci. 35, 313347 [2007].)
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