Global and Temporal Perspective

The first strand of evidence for the global ocean uptake comes from models of the ocean carbon cycle. These generally combine descriptions of the relevant carbonate chemistry with some representation of tracer transport in the ocean. As well they need a model (usually highly simplified) of the biological processes in the ocean and finally some parameterization of the surface fluxes of 

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The second line of evidence comes from the time trends of some atmospheric species, mainly CO, and oxygen. Developing the oxygen budget of the atmosphere, which contains some problematic terms, is beyond the scope of this chapter. Briefly, the global, lojig-term budgets for O2/N2 and CO2 can be written schematically as 

FIGURE 1 Several estimates of the zonal mean flux (Mt C year per degree latitude) from the ocean into the atmosphere. The three blue lines are taken from OCMIP (Orr, 1997), the red line from a regionally aggregated estimate of Takahashi et al. (1997) and the four green lines from four atmospheric inversions as described in the text. 

Fossil-fuel source. Note that this has a significant impact on the terrestrial uncertainty because of its high oxygen-carbon stoichiometric ratio. 

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