Global carbon cycle reservoirs

Fig. 11-18 A four-box model of the global carbon cycle. Reservoir inventories are given in moles and fluxes in mol/yr. The turnover time of CO2 in each reservoir with respect to the outgoing flux is shown in brackets. (Reprinted with permission from L. Machta, The role of the oceans and biosphere in the carbon dioxide cycle, in D. Dryssen and D. Jagner (1972). "The Changing Chemistry of the Oceans," pp. 121-146, John Wiley.)...

Figure 1. The global carbon cycle. Estimates of reservoir size and annual fluxes are from Post et al. (4), Vegetation carbon reservoir was estimated from latest carbon density estimates. All values except the atmospheric reservoir are approximate only. All values are in gigatons. Fluxes are next to the arrows and are in gigatons ear.

Fig. 11-1 Major reservoirs and fluxes of the global carbon cycle, including time scales. Numbers given are Pg C (1 Pg C = lO g C) Pg C/yr, respectively. (After Sundquist, 1993.)...

Additional material on this subject is provided in the supplemental information for Chapter 25.4 that is available online at http //elsevierdirect.eom/companions/9780120885305. Key topics covered are the role of tectonism in the geologic carbon cycle and how the evolution of pelagic calcifiers in the Phanerozoic led to the development of feedbacks, some stabilizing and some destabilizing, that act on the atmospheric COj reservoir. Also included is a short summary of how the global carbon cycle interacts with the atmospheric O2 and sulfur cycles. 

FIGURE 14.11 Summary of global carbon cycle. Amount (in gigatons of C = 109 metric tons = fO1 g of C). Reservoirs are shown in parentheses, and fluxes (gigatons of C per year) are indicated by arrows. Note that the time scales associated with the various processes vary (adapted from IPCC, 1996). 

Major efforts have been made to sharpen this sketch of the global carbon cycle. In part such work consists of quantitative system modelling fe.g., Bolin, 1981), where the chief gains derive from the need to grasp and quantify the nature of the various exchange processes. For the rest, the effort is directed primarily towards actual measurement of the fluxes, or of reservoir content (e.g., Woodwell et al., 1978 Ajtay et al., 1979 Olson, 1982). 

The place of the biological pump in the global carbon cycle is illustrated in Figure 2. The atmosphere exchanges carbon with essentially three reservoirs the ocean, the terrestrial biosphere, and the geosphere. The ocean holds —50 times as much carbon as does the atmosphere, and... 

The global carbon cycle refers to the exchanges of carbon within and between four major reservoirs the atmosphere, the oceans, land, and fossil fuels. Carbon may be transferred from one reservoir to another in seconds (e.g., the fixation... 

Figure 15.19 gives a description of the global carbon cycle. The inventories of the various reservoirs were already given in Table 4.1, where we noticed that the atmosphere is a relatively small reservoir with large fluxes, so that the residence time of C in the atmosphere is only a few years. The carbon system is not at steady state. Because of fossil fuel combustion and possibly also because of deforestation, the inventories of C in the atmosphere and hydrosphere are increasing. The flux related to fossil fiiel combustion is nearly 1 % of the total atmospheric CO2 reservoir. The flux due to land use is more con-troversal but is probably 1-2 X 10 mol C . As the summary at the bottom... 

The global carbon cycle. Values in brackets are preanthropogenic reservoir sizes in Pg (10 g) values on the arrows are fluxes in Pgy . Dashed lines represent the long-term carbon cycle determined by weathering. Values are normalized to the flux of Die from rivers (see Chapter 2). Solid arrows are the shorter-term carbon fluxes associated with photosynthesis and respiration. 

Fig. 7.9 A simplified version of the global carbon cycle for the 1980s. The numbers in boxes indicate the reservoir size in GtC. Arrows represent fluxes and the associated numbers indicate the magnitude of the flux in GtC r. After IPCC (2001). With permission of the Intergovernmental Panel on Climate Change.

Figure 10. The global carbon cycle, showing the reservoirs (in 10 Ions per year) relevant to the anthropogenic perturbation as annual averages over the period 1980 to 1989 (Erswaren et al, 1993 Potter et al, 1993 Siegenthaler and Sarmiento, 1993 Schimel ei al, 2000).

Fig. 11-1 Major reservoirs and fluxes of global carbon cycle.

Fig. 11-24 A summary of the global carbon cycle as described in the text. Reservoir contents are given in Pg C and fluxes in PgC/year.

Fig. 6.1 Simplified summary of the preindustrial global carbon cycle, showing approximate sizes of the main reservoirs (variously shaped boxes) and annual fluxes (arrows) in Gt (1015g) of carbon (after several sources, including Bolin et al. 1979, 1983 Kempe 1979 Mopper Degens 1979 DeVooys 1979 Siegenthaler Sarmiento 1993 Sundquist 1993 Arthur 2000 Falkowski et al. 2000). Reactive sediments are capable of exchanging material with the water column.

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