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energy>Jmdonev at 23:20, 18 February 2020

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	[[Category:Done ~~2016~~-01-15]]		[[Category:Done 2020-02-29]]
	''This page discusses the Earth's natural cycle of carbon - to read about human effects on this cycle [[carbon cycle\|click here]]''		''This page discusses the Earth's natural cycle of carbon - to read about human effects on this cycle [[carbon cycle\|click here]]''

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	Human activities are known to be negatively affecting this cycle. As can be seen in the figure above, human input (all red numbers) are causing a net increase in the atmosphere, soil, and oceans. This net increase stems from the fact that humans pull carbon-rich [[fossil fuel]]s from underground that would otherwise not be part of the cycle, and introduce them into it via [[combustion]]. To learn more about this, visit the [[carbon cycle#Human Effect on the Carbon Cycle\|main article]].		Human activities are known to be negatively affecting this cycle. As can be seen in the figure above, human input (all red numbers) are causing a net increase in the atmosphere, soil, and oceans. This net increase stems from the fact that humans pull carbon-rich [[fossil fuel]]s from underground that would otherwise not be part of the cycle, and introduce them into it via [[combustion]]. To learn more about this, visit the [[carbon cycle#Human Effect on the Carbon Cycle\|main article]].

			==For Further Reading==
			*[[Carbon cycle]]
			*[[Carbon pool]]
			*[[Carbon sink]]
			*[[Greenhouse effect]]
			*[[Carbon capture and storage]]
			*Or explore a [[Special:Random\|random page]]
	==References==		==References==
	{{reflist}}		{{reflist}}
			[[Category:Uploaded]]

Jmdonev: 1 revision imported

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Jmdonev at 20:24, 31 December 2015

2015-12-31T20:24:26Z

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[[Category:Done 2016-01-15]]
''This page discusses the Earth's natural cycle of carbon - to read about human effects on this cycle [[carbon cycle|click here]]''

<onlyinclude>The '''natural carbon cycle''' is the flow of [[carbon]] naturally throughout across the globe in various forms, such as [[carbon dioxide]] or [[methane]].</onlyinclude> This carbon moves through the [[atmosphere]], ocean, terrestrial [[biosphere]], and lithosphere. The natural carbon cycle is kept very nearly in balance; animals and plants emit CO2 into the atmosphere through respiration, while plants absorb it through [[photosynthesis]]. The ocean also cycles CO2 with the atmosphere, in an almost perfect balance. This process cycles carbon rapidly, with a typical molecule of CO2 spending only around 5 years in the atmosphere.<ref name=wolf>R. Wolfson, "Carbon: A Closer Look" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 13, sec. 5, pp. 357-361</ref>

Within the broad view of the carbon cycle are various key cycles, ranging from land to air to ocean. Figure 1 below shows all of the cycles that will be talked about on this page.

==Cycles==

The two main cycles are the land-atmosphere cycle, and the ocean-atmosphere cycle. They both occur on very different timescales, with the land cycle occurring at a high rate while the ocean cycle is much slower.

*'''Land-atmosphere''' - this cycle occurs via two main drivers; photosynthesis and respiration. In photosynthesis, carbon dioxide is absorbed from the atmosphere to create a fuel for the plant, while respiration consumes [[oxygen]] and produces carbon dioxide. Respiration also occurs via decaying matter, in which the compounds making up the matter decompose by bacteria which consumes oxygen along with the matter to produce energy and carbon dioxide.<ref name=cc>M. Melieres and C. Marechal, "Warming in the 20th century," in ''Climate Change: Past, Present and Future'' 1st ed., U.K.: Wiley, 2015, ch.29, sec.1, pp. 298-301</ref>

*'''Ocean-atmosphere''' - the driving mechanism for this cycle is the difference in carbon dioxide's partial pressure between the ocean and atmosphere (partial pressure is the [[pressure]] the gas would have if it occupied the entire volume of the mixed solutions, in this case the volume of the ocean and atmosphere). This pressure varies with both the [[temperature]] of the ocean, and the local marine photosynthesis. The lower the ocean temperature is the less carbon is emitted (much like how a warm glass of pop becomes flat more quickly). Therefore some regions of the ocean take in carbon ([[carbon sink]]) while some emit carbon (carbon source).<ref name=cc/>

[[File:Carbon_cycle.jpg|780px|thumb|center|Figure 1. The carbon cycle of the Earth. Numbers represent the mass of carbon in gigatonnes (not the molecules, just carbon alone) that is cycled in a year. '''Yellow''' text is the natural carbon cycle, with '''red''' text showing human effects.<ref>Wikimedia Commons [Online]. (June 5 2015). Available: http://en.wikipedia.org/wiki/Carbon_cycle#/media/File:Carbon_cycle.jpg</ref> Notice that the 9 gigatonnes of carbon that humans are emitting (~35 gigatonnes of carbon dioxide) becomes an extra 4 gigatonnes in the atmosphere, an extra 3 gigatonnes of photosynthesis and an extra 2 gigatonnes in the ocean every year. This is how humans are changing the natural carbon cycle.]]

==Human effect on this natural cycle==
:''[[carbon cycle#Human Effect on the Carbon Cycle|main article]]''

Human activities are known to be negatively affecting this cycle. As can be seen in the figure above, human input (all red numbers) are causing a net increase in the atmosphere, soil, and oceans. This net increase stems from the fact that humans pull carbon-rich [[fossil fuel]]s from underground that would otherwise not be part of the cycle, and introduce them into it via [[combustion]]. To learn more about this, visit the [[carbon cycle#Human Effect on the Carbon Cycle|main article]].

==References==
{{reflist}}

Natural carbon cycle - Revision history

Jmdonev: 1 revision imported

energy>Jmdonev at 23:20, 18 February 2020

Jmdonev: 1 revision imported

Jmdonev at 20:24, 31 December 2015