The carbon budget

Since the beginning of the Industrial Revolution, humans have emitted about 330 10 g CO2—C from the combustion of fossil fuels and cement production 

It is easy to calculate the amount of CO2 accumulated in the atmosphere. The recent CO2 mixing ratio (382 ppm) corresponds to 822 10 g CO2—C. Taking into account the total mass of the atmosphere (5.2 10 g Table 2.2) it follows that  

From these data, the 350 10 g CO2—C of human carbon emissions over the past 107 years would have increased CO2 concentration from 300 to 465 ppm, if it had all stayed there. Since present carbon dioxide concentration is about 382 ppm, 50 % of the cumulative emissions have been absorbed by the environment assuming, of course, that the carbon source is entirely human (there is no doubt). 

we can simply calculate the future CO2 concentration assuming different CO2 based on the slope given by Fig. 2.91 and assuming (which is not self-evi- 

Scenario b) seems to be very optimistic - it results in a constant CO2 mixing ratio of 465 ppm after 2050. It is more likely that carbon capture and sequestration/ storage (CCS) technology (Chapter 2.8.4) becomes important only after 2030 and will capture a maximum of 50 % of the fossil fuel-released CO2. It is also unlikely that the yearly consumption of fossil fuels will be more reduced before 2050 because of the increasing alternative energy source percentage of the total energy consumption. Hence, in 2050 a value of around 500 ppm CO2 seems more likely. 

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These models are too simple to reflect realistic dynamic properties of the carbon budget. Even so, they depend on data that are poorly measured or lacking. Many potentially important compartments are missing or assumed to be unimportant. For example, no model considers carbon transported from terrestrial systems to the oceans through rivers and streams. While the amount is very small, it is continuous and cumulative (25)... 

Wigley, T. M. L. (1993). Balancing the carbon budget Implications for projections of future carbon dioxide concentration changes, Tellus 45B, 409-425. 

The same interstellar abundance is obtained from observations of the UV bump and the 4,430 A band. The abundances inferred for fullerenes are consistent with estimates for the carbon budget in the ISM. 

Janssens, I. A., Freibauer, A., Schlamadinger, B., Ceulemans, R., Ciais, P, Dolman, A. J., Heimann, M., Nabuurs, G. J., Smith, P, Valentini, R., and Schulze, E. D. (2005). The carbon budget of terrestrial ecosystems at country-scale—A European case study. Biogeosciences 2,15-26. 

Figure 6.7. Simplifed soil carbon cycling scheme. Major inputs (plant litter) to and outputs (respiration and erosion) from the soil carbon reservoir. The observed flux of C out of the soil can be modeled by assuming three pools of carbon an active pool with a turnover time on the order of years, an intermediate pool with a turnover time on the order of decades to centuries, and a passive pool with a turnover time on the order of millennia. The decomposition constant is k = 1/t. Subscripts a, i, and p refer to the active, intermediate, and passive C pools, respectively. Adapted with permission from Amundson, R. (2001). The carbon budget in soils. Annu. Rev. Earth Planet. Sci. 29, 535-562.

Analysis of data on the carbon budget within the WCRP studies of GHG removal from the atmosphere in national parks in 13 states of the U.S.A. yielded interesting results (Kondratyev and Krapivin, 2005). According to these data, in these parks the amount of carbon accumulated in the top 20 cm layer of soil constituted 910 kg ha1 yr 1. Hence, over the whole territory of the program (5.6 million ha) the atmosphere was loosing annually 5.1 million tC. 

There is now the possibility of estimating the carbon budget by using data of satellite observations of ocean color made with SeaWiFS and MODIS instruments calibrated by comparing them with observations by the Marine Optical Buoy (MOBY) (Lavender et al., 1998, 2005 Pinkerton et al., 2003). Calibration ensures that errors in the retrieval of chlorophyll concentration in seawater do not exceed 6%, which makes it possible to substantially raise the reliability of estimates of primary production and, hence, of the carbon budget. 

To promptly estimate the carbon supply in forests of the U.S.A., a computer algorithm, called Cole s parallel merge sort algorithm, was developed and used to specify all available data on the carbon budget inventory (Cole, 1988). 

Arnosti, C., and Holmer, M. (1999) Carbohydrate dynamics and contributions to the carbon budget of an organic-rich coastal sediment. Geochim. Cosmochim. Acta 63, 393—403. 

Kofoed, L.H. (1975) The feeding biology of Hydrobia ventrosa Montagu. II. Allocation of the carbon budget and the significance of the secretion of dissolved organic material. J. Exp. Mar. Biol. Ecol. 19, 233-241. 

Joos, F., Plattner, G. K., Stocker, T. F., Koertzinger, A., and Wallace, D. W. R. (2003). Trends in marine dissolved oxygen Imphcations for ocean circulation changes and the carbon budget. EOS Trans. Am. Geophys. Union 84, 197—204. 

The carbonate budget for the oceanic crust Fbas + Fpei can be written as... 

Terrestrial and marine biomarkers have aided in understanding how Arctic shelf systems process, metabolize and sequester carbon (Opsahl etal., 1999). Biomarkers have been used to trace the dispersal of DOC and POC on the Canadian Beaufort shelf, leading to a better understanding of the importance of terrestrial sources to the carbon budget of major riverine-influenced systems (Yunker etal., 1995 Macdonald etal., 1998). 

Sarmiento JL, Murnane R, and Le Quere C (1995) Air-sea CO2 transfer and the carbon budget of the North Atlantic. Philosophical Transactions of the Royal Society of London, series B 343 211-219. 

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 C02. carbon cycle... 

Venkatesan M. I. and Kaplan I. R. (1992) Vertical and lateral transport of organic carbon and the carbon budget in Santa Monica Basin, California. Prog. Oceanogr. 30, 291-312. 

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