2.3 Biogeochemical Cycles of the Green World (Planet Earth)
39
Fig. 2.5 Phase change diagram, Source: Encyclopædia Britannica (2011a)
2.3.2 Carbon Cycle
The carbon cycle is a type of the biogeochemical cycle and is a term used for
describing the ways carbon moves between the atmosphere, biosphere, hydrosphere,
and lithosphere (see Fig. 2.6). Carbon is critical for the sustenance of various
functions of the planet. It is a significant component of various minerals and
living beings. These spheres act as carbon sinks or reservoirs in the short-term
or long-term. As the Earth is a dynamic environment, processes like respiration,
decomposition, and erosion continually shift carbon between reservoirs (Prentice
et al. 2001). Carbon enters is stored and leaves the various Earth spheres using
various methods and quantities.
In the atmosphere, carbon is stored in the form of carbon dioxide (CO 2 ) and
methane (CH 4 ); greenhouse gases that absorb and retain heat. Living organisms
release CO 2 into the atmosphere through respiration. Photosynthesis and dissolution
are essential processes for removing this gas from the atmosphere. Methane is
released into the atmosphere through processes such as decomposition, combustion
of fossil fuels, and animal emissions.
In the biosphere, all organisms have organic carbon by removing it from
atmospheric CO 2 through photosynthesis or the consumption of other organisms
(Prentice et al. 2001). Often, carbon is retained until an organism decomposes to
39
Fig. 2.5 Phase change diagram, Source: Encyclopædia Britannica (2011a)
2.3.2 Carbon Cycle
The carbon cycle is a type of the biogeochemical cycle and is a term used for
describing the ways carbon moves between the atmosphere, biosphere, hydrosphere,
and lithosphere (see Fig. 2.6). Carbon is critical for the sustenance of various
functions of the planet. It is a significant component of various minerals and
living beings. These spheres act as carbon sinks or reservoirs in the short-term
or long-term. As the Earth is a dynamic environment, processes like respiration,
decomposition, and erosion continually shift carbon between reservoirs (Prentice
et al. 2001). Carbon enters is stored and leaves the various Earth spheres using
various methods and quantities.
In the atmosphere, carbon is stored in the form of carbon dioxide (CO 2 ) and
methane (CH 4 ); greenhouse gases that absorb and retain heat. Living organisms
release CO 2 into the atmosphere through respiration. Photosynthesis and dissolution
are essential processes for removing this gas from the atmosphere. Methane is
released into the atmosphere through processes such as decomposition, combustion
of fossil fuels, and animal emissions.
In the biosphere, all organisms have organic carbon by removing it from
atmospheric CO 2 through photosynthesis or the consumption of other organisms
(Prentice et al. 2001). Often, carbon is retained until an organism decomposes to