Carbon cycles, global biosphere

Carbon. Most of the Earth s supply of carbon is stored in carbonate rocks in the Hthosphere. Normally the circulation rate for Hthospheric carbon is slow compared with that of carbon between the atmosphere and biosphere. The carbon cycle has received much attention in recent years as a result of research into the possible relation between increased atmospheric carbon dioxide concentration, most of which is produced by combustion of fossil fuel, and the "greenhouse effect," or global warming. Extensive research has been done on the rate at which carbon dioxide might be converted to cellulose and other photosyntheticaHy produced organic compounds by various forms of natural and cultivated plants. Estimates also have been made of the rate at which carbon dioxide is released to soil under optimum conditions by various kinds of plant cover, such as temperature-zone deciduous forests, cultivated farm crops, prairie grassland, and desert vegetation. 

The global carbon cycle is the continuous movement of carbon between the living and nonliving portions of the biosphere, driven in part by biological processes and resulting in a constant supply of carbon to life (Figure 1). The... 

Olson, J. S. Pfoderer, H. A. Chan, Y. H. Changes in the Global Carbon Cycle and the Biosphere ORNL/EIS-109, Oak Ridge National Laboratory Oak Ridge, TN, 1978. 

This treatment of the carbon cycle is intended to give an account of the fundamental aspects of the carbon cycle from a global perspective. After a presentation of the main characteristics of carbon on Earth (Section 11.2), four sections follow 11.3, about the carbon reservoirs within the atmosphere, the hydrosphere, the biosphere... 

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.)...

Post, W. M., King, A. W. and Wullschleger, S. D. (1997). Historical variations in terrestrial biospheric carbon storage, Global Biogeochem. Cycles 11, 99-109. 

Hudson R. J. M. et al. (1994). Modeling the global carbon cycle Nitrogen fertilization of the terrestrial biosphere and the "missing" CO2 sink. Global Bio-geochem. Cycles 8, 307-333. 

Sources http //www. Idea. Columbia. edu/edu/deesA/1003/lectures/global carbon cycle/index. html and http //en.wikipedia.org/wiki/Carbon cycle0ln the biosphere ... 

To analyze the dynamics of C02 in the biosphere, it is important to take into account the maximum possible number of its reservoirs and fluxes as well as their spatial distribution. It is in this that numerous global models of the carbon cycle differ. The present level of these studies does not allow us to answer the principal question as to how extensive is information in the database about the supplies and fluxes of carbon. Therefore, many authors analyzing the dynamic characteristics... 

Tarko A.M. (2001). Investigation of global biosphere processes with the aid of a global spatial carbon dioxide cycle model. Proceedings of the Sixth International Carbon Dioxide Conference, Extended Abstracts (October 1-2, 2001, Tohoku University, Sendai, Japan), Yol. 2, pp. 899-902. 

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... 

Carbon-cycle responses to Holocene climate change have been hypothesized to explain the atmospheric CO2 and CH4 trends observed in the ice-core record of this period. The early Holocene expansion of terrestrial vegetation and soils in areas that were previously glaciated has been suggested as the cause of the early Holocene decrease in CO2 (Indermuhle et al., 1999). Likewise, the increase in atmospheric CO2 between 8 ka and I ka has been attributed to a release of biospheric carbon caused by a global trend during... 

Figure 1.5 extends this notion to the geochemical level which shows an estimate of the influence of the global biosphere carbon and oxygen cycles on the fluxes of major elements through the terrestrial reservoirs, and includes the effects of both primary and secondary biogeochemical processes. 

The exchange of CO2 between atmosphere and terrestrial biota is one of the prime links in the global carbon cycle. This is seen by studying the variations of C in the atmosphere. Figure 11-9 presents atmospheric <5 C for the years 1956 and 1978. The lines are consistent with addition or subtraction of CO2 with a d C of about — 27%o. This CO2 could be derived from either fossil fuel or plants. It cannot be oceanic, since surface water DIC has a 6 C of about + 2%o (Kroopnick, 1980). This confirms that the annual P Oj variations are primarily due to exchange with the terrestrial biosphere, and not caused by seasonal exchange with the oceans. 

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