Editing Carbon cycle (section)

===Geosphere===
{{Main|Carbonate–silicate cycle}}
[[File:Global carbon stocks.png|thumb|left|upright=1.8|Diagram showing relative sizes (in gigatonnes) of the main storage pools of carbon on Earth. Cumulative changes (thru year 2014) from land use and emissions of fossil carbon are included for comparison.<ref name="janow"/>]]
The geologic component of the carbon cycle operates slowly in comparison to the other parts of the global carbon cycle. It is one of the most important determinants of the amount of carbon in the atmosphere, and thus of global temperatures.<ref name=NASA>{{Cite web |title=The Slow Carbon Cycle |url=http://earthobservatory.nasa.gov/Features/CarbonCycle/page2.php |publisher=NASA |access-date=2012-06-24 |archive-url=https://web.archive.org/web/20120616151904/http://earthobservatory.nasa.gov/Features/CarbonCycle/page2.php |archive-date=16 June 2012 |url-status=live |df=dmy-all |date=2011-06-16 }}</ref>

Most of the Earth's carbon is stored inertly in the Earth's [[lithosphere]].<ref name=GlobalCarbonCycle/> Much of the carbon stored in the Earth's mantle was stored there when the Earth formed.<ref name=DiVenere2012>[http://www.columbia.edu/~vjd1/carbon.htm The Carbon Cycle and Earth's Climate] {{Webarchive|url=https://web.archive.org/web/20030623195122/http://www.columbia.edu/~vjd1/carbon.htm |date=23 June 2003 }} Information sheet for Columbia University Summer Session 2012 Earth and Environmental Sciences Introduction to Earth Sciences I</ref> Some of it was deposited in the form of organic carbon from the biosphere.<ref name=Berner1999>{{cite journal |last1=Berner |first1=Robert A. |title=A New Look at the Long-term Carbon Cycle|journal=GSA Today |date=November 1999 |volume=9 |issue=11 |pages=1&ndash;6 |url=https://www.geosociety.org/gsatoday/archive/9/11/pdf/gt9911.pdf |archive-url=https://web.archive.org/web/20190213183546/https://www.geosociety.org/gsatoday/archive/9/11/pdf/gt9911.pdf |archive-date=2019-02-13 |url-status=live }}</ref> Of the carbon stored in the geosphere, about 80% is [[limestone]] and its derivatives, which form from the sedimentation of [[calcium carbonate]] stored in the shells of marine organisms. The remaining 20% is stored as [[kerogen]]s formed through the sedimentation and burial of terrestrial organisms under high heat and pressure. Organic carbon stored in the geosphere can remain there for millions of years.<ref name=NASA/>

Carbon can leave the geosphere in several ways. Carbon dioxide is released during the [[metamorphism]] of carbonate rocks when they are [[Subduction|subducted]] into the Earth's mantle. This carbon dioxide can be released into the atmosphere and ocean through [[Volcanism|volcanoes]] and [[Hotspot (geology)|hotspots]].<ref name=DiVenere2012/> It can also be removed by humans through the direct extraction of kerogens in the form of [[fossil fuels]]. After extraction, fossil fuels are burned to release energy and emit the carbon they store into the atmosphere.

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