Editing Carbon cycle (section)

===Terrestrial biosphere===
[[File:Carbon stored in ecosystems.png|thumb|right|upright=1.35|Amount of carbon stored in Earth's various terrestrial ecosystems, in gigatonnes.<ref name="janow">{{cite report |doi=10.2737/WO-GTR-95 |doi-access=free |title=Considering Forest and Grassland Carbon in Land Management |date=2017 |last1=Janowiak |first1=M. |last2=Connelly |first2=W.J. |last3=Dante-Wood |first3=K. |last4=Domke |first4=G.M. |last5=Giardina |first5=C. |last6=Kayler |first6=Z. |last7=Marcinkowski |first7=K. |last8=Ontl |first8=T. |last9=Rodriguez-Franco |first9=C. |last10=Swanston |first10=C. |last11=Woodall |first11=C.W. |last12=Buford |first12=M. |publisher=United States Department of Agriculture, Forest Service }}</ref>]]
{{Main|Terrestrial biological carbon cycle}}

The terrestrial biosphere includes the organic carbon in all land-living organisms, both alive and dead, as well as carbon stored in [[soil]]s. About 500 gigatons of carbon are stored above ground in plants and other living organisms,<ref name=Prentice_etal_2001/> while soil holds approximately 1,500 gigatons of carbon.<ref>{{cite journal|last1=Rice|first1=Charles W.|title=Storing carbon in soil: Why and how?|journal=Geotimes|date=January 2002|volume=47|issue=1|pages=14&ndash;17|url=http://www.geotimes.org/jan02/feature_carbon.html|access-date=5 April 2018|archive-url=https://web.archive.org/web/20180405153123/http://www.geotimes.org/jan02/feature_carbon.html|archive-date=5 April 2018|url-status=live|df=dmy-all}}</ref> Most carbon in the terrestrial biosphere is organic carbon,<ref>{{cite journal|doi=10.1111/gcbb.12401|title=Investigating the biochar effects on C-mineralization and sequestration of carbon in soil compared with conventional amendments using the stable isotope (δ<sup>13</sup>C) approach|journal=GCB Bioenergy|volume=9|issue=6|pages=1085–1099|year=2016|last1=Yousaf|first1=Balal|last2=Liu|first2=Guijian|last3=Wang|first3=Ruwei|last4=Abbas|first4=Qumber|last5=Imtiaz|first5=Muhammad|last6=Liu|first6=Ruijia|doi-access=free}}</ref>  while about a third of [[soil carbon]] is stored in inorganic forms, such as [[calcium carbonate]].<ref name=Lal-2008>{{Cite journal |doi=10.1039/b809492f |title=Sequestration of atmospheric CO<sub>2</sub> in global carbon pools |last=Lal |first=Rattan |journal=Energy and Environmental Science |volume=1 |pages=86–100 |year=2008|issue=1 |bibcode=2008EnEnS...1...86L }}</ref> Organic carbon is a major component of all organisms living on Earth. [[Autotrophs]] extract it from the air in the form of carbon dioxide, converting it to organic carbon, while [[heterotrophs]] receive carbon by consuming other organisms.

Because carbon uptake in the terrestrial biosphere is dependent on biotic factors, it follows a diurnal and seasonal cycle. In CO<sub>2</sub> measurements, this feature is apparent in the [[Keeling curve]]. It is strongest in the northern [[Hemisphere of the Earth|hemisphere]] because this hemisphere has more land mass than the southern hemisphere and thus more room for ecosystems to absorb and emit carbon.

[[File:SRS1000 being used to measure soil respiration in the field..jpg|thumb|upright=1.2|left|A portable soil respiration system measuring soil CO<sub>2</sub> flux.]]

Carbon leaves the terrestrial biosphere in several ways and on different time scales. The [[combustion]] or [[Cellular respiration|respiration]] of organic carbon releases it rapidly into the atmosphere. It can also be exported into the ocean through rivers or remain sequestered in soils in the form of inert carbon.<ref>{{cite journal |doi=10.1016/j.ecolind.2017.04.049 |title=The carbon flux of global rivers: A re-evaluation of amount and spatial patterns |journal=Ecological Indicators |volume=80 |pages=40–51 |year=2017 |last1=Li |first1=Mingxu |last2=Peng |first2=Changhui |last3=Wang |first3=Meng |last4=Xue |first4=Wei |last5=Zhang |first5=Kerou |last6=Wang |first6=Kefeng |last7=Shi |first7=Guohua |last8=Zhu |first8=Qiuan |bibcode=2017EcInd..80...40L }}</ref> Carbon stored in soil can remain there for up to thousands of years before being washed into rivers by [[erosion]] or released into the atmosphere through [[soil respiration]]. Between 1989 and 2008 soil respiration increased by about 0.1% per year.<ref>{{cite journal |doi=10.1038/nature08930 |pmid=20336143 |title=Temperature-associated increases in the global soil respiration record |journal=Nature |volume=464 |issue=7288 |pages=579–582 |year=2010 |last1=Bond-Lamberty |first1=Ben |last2=Thomson |first2=Allison |bibcode=2010Natur.464..579B |s2cid=4412623 }}</ref> In 2008, the global total of CO<sub>2</sub> released by soil respiration was roughly 98 billion tonnes{{citation needed|date=April 2024}}, about 3 times more carbon than humans are now putting into the atmosphere each year by burning fossil fuel (this does not represent a net transfer of carbon from soil to atmosphere, as the respiration is largely offset by inputs to soil carbon).{{citation needed|date=April 2024}} There are a few plausible explanations for this trend, but the most likely explanation is that increasing temperatures have increased rates of decomposition of [[soil organic matter]], which has increased the flow of CO<sub>2</sub>. The length of carbon sequestering in soil is dependent on local climatic conditions and thus changes in the course of [[climate change]].<ref name="Varney">{{cite journal |last1=Varney |first1=Rebecca M. |last2=Chadburn |first2=Sarah E. |last3=Friedlingstein |first3=Pierre |last4=Burke |first4=Eleanor J. |last5=Koven |first5=Charles D. |last6=Hugelius |first6=Gustaf |last7=Cox |first7=Peter M. |title=A spatial emergent constraint on the sensitivity of soil carbon turnover to global warming |journal=Nature Communications |date=2 November 2020 |volume=11 |issue=1 |page=5544 |doi=10.1038/s41467-020-19208-8 |pmid=33139706 |pmc=7608627 |bibcode=2020NatCo..11.5544V }}</ref> <!-- From pre-industrial era to 2010, the terrestrial biosphere represented a net source of atmospheric CO<sub>2</sub> prior to 1940, switching subsequently to a net sink.<ref>{{cite journal |last1=Huang |first1=Junling |last2=McElroy |first2=Michael B. |title=The contemporary and historical budget of atmospheric CO 2 1 This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career. |journal=Canadian Journal of Physics |date=August 2012 |volume=90 |issue=8 |pages=707–716 |doi=10.1139/p2012-033 }}</ref> -->

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{| class=wikitable align="right" style="text-align:left; font-size:0.9em"
|+ Size of major carbon pools on the Earth (year 2000 estimates)<ref name=GlobalCarbonCycle/>
! Pool !! Quantity<br>(gigatons)
|-
| Atmosphere || 720
|-
| Ocean (total) || 38,400
|-
| style="padding-left: 2em" | Total inorganic || 37,400
|-
| style="padding-left: 2em" | Total organic || 1,000
|-
| style="padding-left: 2em" | Surface layer || 670
|-
| style="padding-left: 2em" | Deep layer || 36,730
|-
| [[Lithosphere]] || 
|-
| style="padding-left: 2em" | Sedimentary carbonates || > 60,000,000
|-
| style="padding-left: 2em" | [[Kerogen]]s || 15,000,000
|-
| Terrestrial biosphere (total) || 2,000
|-
| style="padding-left: 2em" | Living biomass || 600 – 1,000
|-
| style="padding-left: 2em" | Dead biomass || 1,200
|-
| Aquatic biosphere || 1 – 2
|-
| Fossil fuels (total) || 4,130
|-
| style="padding-left: 2em" | Coal || 3,510
|-
| style="padding-left: 2em" | Oil || 230
|-
| style="padding-left: 2em" | Gas || 140
|-
| style="padding-left: 2em" | Other ([[peat]]) || 250
|}