Editing Carbon cycle (section)

==Human influence on fast carbon cycle==
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[[File:Anthropogenic changes in the global carbon cycle.png|thumb|upright=1.7|right|Schematic representation of the overall perturbation of the global carbon cycle caused by anthropogenic activities, averaged from 2010 to 2019.]]

Since the [[Industrial Revolution]], and especially since the end of [[WWII]], human activity has substantially disturbed the global carbon cycle by redistributing massive amounts of carbon from the geosphere.<ref name="nasacc" />   Humans have also continued to shift the natural component functions of the terrestrial biosphere with changes to vegetation and other land use.<ref name=GlobalCarbonCycle/>   Man-made (synthetic) carbon compounds have been designed and mass-manufactured that will persist for decades to millennia in air, water, and sediments as pollutants.<ref>{{cite web |url=https://www.epa.gov/ghgemissions/overview-greenhouse-gases |title=Overview of greenhouse gases |date=23 December 2015 |publisher=U.S. Environmental Protection Agency |access-date=2020-11-02}}</ref><ref name="plaspol">{{cite news |title=The known unknowns of plastic pollution |url=https://www.economist.com/news/international/21737498-so-far-it-seems-less-bad-other-kinds-pollution-about-which-less-fuss-made |access-date=17 June 2018 |newspaper=The Economist |date=3 March 2018}}</ref>   Climate change is amplifying and forcing further indirect human changes to the carbon cycle as a consequence of various positive and negative [[feedback]]s.<ref name="Varney" />

=== Climate change ===
{{Main|Climate change feedback|Effects of climate change on oceans}}

[[File:Climate–carbon cycle feedbacks and state variables.png|thumb|upright=2|right| {{center|'''Climate–carbon cycle feedbacks and state variables<br />as represented in a stylised model'''}} Carbon stored on land in vegetation and soils is aggregated into a single stock c<sub>t</sub>. Ocean mixed layer carbon, c<sub>m</sub>, is the only explicitly modelled ocean stock of carbon; though to estimate carbon cycle feedbacks the total ocean carbon is also calculated.<ref name="Donges2018">{{cite journal |last1=Lade |first1=Steven J. |last2=Donges |first2=Jonathan F. |last3=Fetzer |first3=Ingo |last4=Anderies |first4=John M. |last5=Beer |first5=Christian |last6=Cornell |first6=Sarah E. |last7=Gasser |first7=Thomas |last8=Norberg |first8=Jon |last9=Richardson |first9=Katherine |last10=Rockström |first10=Johan |last11=Steffen |first11=Will |year=2018 |title=Analytically tractable climate–carbon cycle feedbacks under 21st century anthropogenic forcing |journal=Earth System Dynamics |volume=9 |issue=2 |pages=507–523 |bibcode=2018ESD.....9..507L |doi=10.5194/esd-9-507-2018 |doi-access=free |hdl=1885/163968 |hdl-access=free }}{{Creative Commons text attribution notice|cc=by4|url=|author(s)=|vrt=|from this source=yes}}</ref>]]

Current trends in climate change lead to higher ocean temperatures and [[acidity]], thus modifying marine ecosystems.<ref>{{cite journal |last1=Takahashi |first1=Taro |last2=Sutherland |first2=Stewart C. |last3=Sweeney |first3=Colm |last4=Poisson |first4=Alain |last5=Metzl |first5=Nicolas |last6=Tilbrook |first6=Bronte |last7=Bates |first7=Nicolas |last8=Wanninkhof |first8=Rik |last9=Feely |first9=Richard A. |last10=Sabine |first10=Christopher |last11=Olafsson |first11=Jon |last12=Nojiri |first12=Yukihiro |year=2002 |title=Global sea–air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects |journal=Deep Sea Research Part II: Topical Studies in Oceanography |volume=49 |issue=9–10 |pages=1601–1622 |bibcode=2002DSRII..49.1601T |doi=10.1016/S0967-0645(02)00003-6}}</ref> Also, acid rain and polluted runoff from agriculture and industry change the ocean's chemical composition. Such changes can have dramatic effects on highly sensitive ecosystems such as [[coral reef]]s,<ref>{{cite journal |last1=Orr |first1=James C. |last2=Fabry |first2=Victoria J. |last3=Aumont |first3=Olivier |last4=Bopp |first4=Laurent |last5=Doney |first5=Scott C. |last6=Feely |first6=Richard A. |last7=Gnanadesikan |first7=Anand |last8=Gruber |first8=Nicolas |last9=Ishida |first9=Akio |last10=Joos |first10=Fortunat |last11=Key |first11=Robert M. |last12=Lindsay |first12=Keith |last13=Maier-Reimer |first13=Ernst |last14=Matear |first14=Richard |last15=Monfray |first15=Patrick |last16=Mouchet |first16=Anne |last17=Najjar |first17=Raymond G. |last18=Plattner |first18=Gian-Kasper |last19=Rodgers |first19=Keith B. |last20=Sabine |first20=Christopher L. |last21=Sarmiento |first21=Jorge L. |last22=Schlitzer |first22=Reiner |last23=Slater |first23=Richard D. |last24=Totterdell |first24=Ian J. |last25=Weirig |first25=Marie-France |last26=Yamanaka |first26=Yasuhiro |last27=Yool |first27=Andrew |title=Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms |journal=Nature |date=September 2005 |volume=437 |issue=7059 |pages=681–686 |doi=10.1038/nature04095 |pmid=16193043 |bibcode=2005Natur.437..681O |s2cid=4306199 |hdl=1912/370 |url=https://epic.awi.de/id/eprint/13479/1/Orr2005a.pdf |hdl-access=free }}</ref> thus limiting the ocean's ability to absorb carbon from the atmosphere on a regional scale and reducing oceanic biodiversity globally.

The exchanges of carbon between the atmosphere and other components of the Earth system, collectively known as the carbon cycle, currently constitute important negative (dampening) feedbacks on the effect of anthropogenic carbon emissions on climate change. Carbon sinks in the land and the ocean each currently take up about one-quarter of anthropogenic carbon emissions each year.<ref>{{cite journal |last1=Le Quéré |first1=Corinne |last2=Andrew |first2=Robbie M. |last3=Canadell |first3=Josep G. |last4=Sitch |first4=Stephen |last5=Korsbakken |first5=Jan Ivar |last6=Peters |first6=Glen P. |last7=Manning |first7=Andrew C. |last8=Boden |first8=Thomas A. |last9=Tans |first9=Pieter P. |last10=Houghton |first10=Richard A. |last11=Keeling |first11=Ralph F. |last12=Alin |first12=Simone |last13=Andrews |first13=Oliver D. |last14=Anthoni |first14=Peter |last15=Barbero |first15=Leticia |display-authors=29 |year=2016 |title=Global Carbon Budget 2016 |journal=Earth System Science Data |volume=8 |issue=2 |pages=605–649 |bibcode=2016ESSD....8..605L |doi=10.5194/essd-8-605-2016 |doi-access=free |last16=Bopp |first16=Laurent |last17=Chevallier |first17=Frédéric |last18=Chini |first18=Louise P. |last19=Ciais |first19=Philippe |last20=Currie |first20=Kim |last21=Delire |first21=Christine |last22=Doney |first22=Scott C. |last23=Friedlingstein |first23=Pierre |last24=Gkritzalis |first24=Thanos |last25=Harris |first25=Ian |last26=Hauck |first26=Judith |last27=Haverd |first27=Vanessa |last28=Hoppema |first28=Mario |last29=Klein Goldewijk |first29=Kees |last30=Jain |first30=Atul K.|hdl=10871/26418 |hdl-access=free }}</ref><ref name="Donges2018" />

These feedbacks are expected to weaken in the future, amplifying the effect of anthropogenic carbon emissions on climate change.<ref>{{cite book |url=https://research-information.bris.ac.uk/en/publications/8d2134c0-3c0e-4e9b-b4d0-c52b6b8f2dfa |title=Climate Change 2013 - the Physical Science Basis |year=2014 |isbn=9781107415324 |editor1-last=Intergovernmental Panel On Climate Change |pages=465–570 |chapter=Carbon and Other Biogeochemical Cycles |publisher=Cambridge University Press |doi=10.1017/CBO9781107415324.015 |hdl=11858/00-001M-0000-0023-E34E-5}}</ref> The degree to which they will weaken, however, is highly uncertain, with Earth system models predicting a wide range of land and ocean carbon uptakes even under identical atmospheric concentration or emission scenarios.<ref>{{cite journal |last1=Joos |first1=F. |last2=Roth |first2=R. |last3=Fuglestvedt |first3=J. S. |last4=Peters |first4=G. P. |last5=Enting |first5=I. G. |last6=von Bloh |first6=W. |last7=Brovkin |first7=V. |last8=Burke |first8=E. J. |last9=Eby |first9=M. |last10=Edwards |first10=N. R. |last11=Friedrich |first11=T. |last12=Frölicher |first12=T. L. |last13=Halloran |first13=P. R. |last14=Holden |first14=P. B. |last15=Jones |first15=C. |year=2013 |title=Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis |journal=Atmospheric Chemistry and Physics |volume=13 |issue=5 |pages=2793–2825 |bibcode=2013ACP....13.2793J |doi=10.5194/acp-13-2793-2013 |doi-access=free |last16=Kleinen |first16=T. |last17=MacKenzie |first17=F. T. |last18=Matsumoto |first18=K. |last19=Meinshausen |first19=M. |last20=Plattner |first20=G.-K. |last21=Reisinger |first21=A. |last22=Segschneider |first22=J. |last23=Shaffer |first23=G. |last24=Steinacher |first24=M. |last25=Strassmann |first25=K. |last26=Tanaka |first26=K. |last27=Timmermann |first27=A. |last28=Weaver |first28=A. J.|hdl=20.500.11850/58316 |hdl-access=free }}</ref><ref name="Donges2018" /><ref>{{cite news |last1=Hausfather |first1=Zeke |last2=Betts |first2=Richard |title=Analysis: How 'carbon-cycle feedbacks' could make global warming worse |url=https://www.carbonbrief.org/analysis-how-carbon-cycle-feedbacks-could-make-global-warming-worse/ |work=Carbon Brief |date=14 April 2020 }}</ref> [[Arctic methane emissions]] indirectly caused by anthropogenic global warming also affect the carbon cycle and contribute to further warming.

==== Fossil carbon extraction and burning ====
{{See also|Coal mining|Extraction of petroleum}}
[[File:Anthropogenic carbon flows 1850-2018.png|thumb|upright=1.2|right| Detail of anthropogenic carbon flows, showing cumulative mass in gigatons during years 1850–2018 (left) and the annual mass average during 2009–2018 (right).<ref name="gcb19">{{cite journal |last1=Friedlingstein |first1=Pierre |last2=Jones |first2=Matthew W. |last3=O'Sullivan |first3=Michael |last4=Andrew |first4=Robbie M. |last5=Hauck |first5=Judith |last6=Peters |first6=Glen P. |last7=Peters |first7=Wouter |last8=Pongratz |first8=Julia |last9=Sitch |first9=Stephen |last10=Le Quéré |first10=Corinne |last11=Bakker |first11=Dorothee C. E. |last12=Canadell |first12=Josep G. |last13=Ciais |first13=Philippe |last14=Jackson |first14=Robert B. |last15=Anthoni |first15=Peter |last16=Barbero |first16=Leticia |last17=Bastos |first17=Ana |last18=Bastrikov |first18=Vladislav |last19=Becker |first19=Meike |last20=Bopp |first20=Laurent |last21=Buitenhuis |first21=Erik |last22=Chandra |first22=Naveen |last23=Chevallier |first23=Frédéric |last24=Chini |first24=Louise P. |last25=Currie |first25=Kim I. |last26=Feely |first26=Richard A. |last27=Gehlen |first27=Marion |last28=Gilfillan |first28=Dennis |last29=Gkritzalis |first29=Thanos |last30=Goll |first30=Daniel S. |last31=Gruber |first31=Nicolas |last32=Gutekunst |first32=Sören |last33=Harris |first33=Ian |last34=Haverd |first34=Vanessa |last35=Houghton |first35=Richard A. |last36=Hurtt |first36=George |last37=Ilyina |first37=Tatiana |last38=Jain |first38=Atul K. |last39=Joetzjer |first39=Emilie |last40=Kaplan |first40=Jed O. |last41=Kato |first41=Etsushi |last42=Klein Goldewijk |first42=Kees |last43=Korsbakken |first43=Jan Ivar |last44=Landschützer |first44=Peter |last45=Lauvset |first45=Siv K. |last46=Lefèvre |first46=Nathalie |last47=Lenton |first47=Andrew |last48=Lienert |first48=Sebastian |last49=Lombardozzi |first49=Danica |last50=Marland |first50=Gregg |last51=McGuire |first51=Patrick C. |last52=Melton |first52=Joe R. |last53=Metzl |first53=Nicolas |last54=Munro |first54=David R. |last55=Nabel |first55=Julia E. M. S. |last56=Nakaoka |first56=Shin-Ichiro |last57=Neill |first57=Craig |last58=Omar |first58=Abdirahman M. |last59=Ono |first59=Tsuneo |last60=Peregon |first60=Anna |last61=Pierrot |first61=Denis |last62=Poulter |first62=Benjamin |last63=Rehder |first63=Gregor |last64=Resplandy |first64=Laure |last65=Robertson |first65=Eddy |last66=Rödenbeck |first66=Christian |last67=Séférian |first67=Roland |last68=Schwinger |first68=Jörg |last69=Smith |first69=Naomi |last70=Tans |first70=Pieter P. |last71=Tian |first71=Hanqin |last72=Tilbrook |first72=Bronte |last73=Tubiello |first73=Francesco N. |last74=van der Werf |first74=Guido R. |last75=Wiltshire |first75=Andrew J. |last76=Zaehle |first76=Sönke |title=Global Carbon Budget 2019 |journal=Earth System Science Data |date=4 December 2019 |volume=11 |issue=4 |pages=1783–1838 |doi=10.5194/essd-11-1783-2019 |doi-access=free |bibcode=2019ESSD...11.1783F |hdl=20.500.11850/385668 |hdl-access=free }}</ref>]]
The largest and one of the fastest growing human impacts on the carbon cycle and biosphere is the extraction and burning of [[fossil fuels]], which directly transfer carbon from the geosphere into the atmosphere. Carbon dioxide is also produced and released during the [[calcination]] of [[limestone]] for [[clinker (cement)|clinker]] production.<ref>IPCC (2007) [https://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch7s7-4-5.html 7.4.5 Minerals] {{Webarchive|url=https://web.archive.org/web/20160525042327/http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch7s7-4-5.html|date=25 May 2016}} in ''Climate Change 2007'': Working Group III: Mitigation of Climate Change,</ref> Clinker is an industrial [[precursor (chemistry)|precursor]] of [[cement]].

{{As of|2020|}}, about 450 gigatons of fossil carbon have been extracted in total; an amount approaching the carbon contained in all of Earth's living terrestrial biomass.<ref name="gcb19" />  Recent rates of global emissions directly into the atmosphere have exceeded the uptake by vegetation and the oceans.<ref name="NASA-20151112-ab">{{cite web |last1=Buis |first1=Alan |last2=Ramsayer |first2=Kate |last3=Rasmussen |first3=Carol |date=12 November 2015 |title=A Breathing Planet, Off Balance |url=http://www.jpl.nasa.gov/news/news.php?feature=4769 |url-status=live |archive-url=https://web.archive.org/web/20151114055636/http://www.jpl.nasa.gov/news/news.php?feature=4769 |archive-date=14 November 2015 |access-date=13 November 2015 |website=[[NASA]] |df=dmy-all}}</ref><ref name="NASA-20151112b">{{cite web |date=12 November 2015 |title=Audio (66:01) - NASA News Conference - Carbon & Climate Telecon |url=http://www.ustream.tv/recorded/77531778 |url-status=live |archive-url=https://web.archive.org/web/20151117033437/http://www.ustream.tv/recorded/77531778 |archive-date=17 November 2015 |access-date=12 November 2015 |website=[[NASA]] |df=dmy-all}}</ref><ref name="NYT-20151110">{{cite news |last=St. Fleur |first=Nicholas |date=10 November 2015 |title=Atmospheric Greenhouse Gas Levels Hit Record, Report Says |work=[[The New York Times]] |url=https://www.nytimes.com/2015/11/11/science/atmospheric-greenhouse-gas-levels-hit-record-report-says.html |url-status=live |access-date=11 November 2015 |archive-url=https://web.archive.org/web/20151111074131/http://www.nytimes.com/2015/11/11/science/atmospheric-greenhouse-gas-levels-hit-record-report-says.html |archive-date=11 November 2015 |df=dmy-all}}</ref><ref name="AP-20151109">{{cite news |last=Ritter |first=Karl |date=9 November 2015 |title=UK: In 1st, global temps average could be 1 degree C higher |work=[[AP News]] |url=http://apnews.excite.com/article/20151109/climate_countdown-greenhouse_gases-d8a21f0397.html |url-status=live |access-date=11 November 2015 |archive-url=https://web.archive.org/web/20151117021206/http://apnews.excite.com/article/20151109/climate_countdown-greenhouse_gases-d8a21f0397.html |archive-date=17 November 2015 |df=dmy-all}}</ref> These [[carbon sink|sink]]s have been expected and observed to remove about half of the added atmospheric carbon within about a century.<ref name="gcb19" /><ref name=":0" /><ref>{{cite book |title=Intergovernmental Panel on Climate Change Fifth Assessment Report |page=8SM-16 |chapter=Figure 8.SM.4 |chapter-url=https://www.ipcc.ch/site/assets/uploads/2018/07/WGI_AR5.Chap_.8_SM.pdf |archive-url=https://web.archive.org/web/20190313233759/https://www.ipcc.ch/site/assets/uploads/2018/07/WGI_AR5.Chap_.8_SM.pdf |archive-date=2019-03-13 |url-status=live}}</ref> Nevertheless, sinks like the ocean have evolving [[solubility pump|saturation properties]], and a substantial fraction (20–35%, based on [[Coupled Model Intercomparison Project|coupled models]]) of the added carbon is projected to remain in the atmosphere for centuries to millennia.<ref>{{cite journal |last=Archer |first=David |year=2009 |title=Atmospheric lifetime of fossil fuel carbon dioxide |journal=Annual Review of Earth and Planetary Sciences |volume=37 |issue=1 |pages=117–34 |bibcode=2009AREPS..37..117A |doi=10.1146/annurev.earth.031208.100206 |hdl=2268/12933 |doi-access=free |hdl-access=free }}</ref><ref>{{Cite journal |last1=Joos |first1=F. |last2=Roth |first2=R. |last3=Fuglestvedt |first3=J.D. |display-authors=etal |year=2013 |title=Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis |url=https://www.atmos-chem-phys.net/13/2793/2013/ |journal=Atmospheric Chemistry and Physics |volume=13 |issue=5 |pages=2793–2825 |doi=10.5194/acpd-12-19799-2012 |doi-access=free |hdl=20.500.11850/58316 |hdl-access=free }}</ref>

====Halocarbons====
{{See also|Halocarbons|Fluorinated gases}}

Halocarbons are less prolific compounds developed for diverse uses throughout industry; for example as [[solvent]]s and [[refrigerant]]s.  Nevertheless, the buildup of relatively small concentrations (parts per trillion) of [[chlorofluorocarbon]], [[hydrofluorocarbon]], and [[perfluorocarbon]] gases in the atmosphere is responsible for about 10% of the total direct [[radiative forcing]] from all long-lived greenhouse gases (year 2019); which includes forcing from the much larger concentrations of carbon dioxide and methane.<ref>{{Cite web |last1=Butler |first1=J. |last2=Montzka |first2=S. |year=2020 |title=The NOAA Annual Greenhouse Gas Index (AGGI) |url=https://www.esrl.noaa.gov/gmd/aggi/aggi.html |publisher=[[NOAA]] Global Monitoring Laboratory/Earth System Research Laboratories}}</ref>  Chlorofluorocarbons also cause stratospheric [[ozone depletion]]. International efforts are ongoing under the [[Montreal Protocol]] and [[Kyoto Protocol]] to control rapid growth in the industrial manufacturing and use of these environmentally potent gases. For some applications more benign alternatives such as [[hydrofluoroolefin]]s have been developed and are being gradually introduced.<ref>{{cite news |last1=Sciance |first1=Fred |date=October 29, 2013 |title=The Transition from HFC- 134a to a Low -GWP Refrigerant in Mobile Air Conditioners HFO -1234yf |work=General Motors Public Policy Center |url=https://www.epa.gov/sites/production/files/2014-09/documents/sciance.pdf |url-status=live |access-date=1 August 2018 |archive-url=https://web.archive.org/web/20151015181041/http://www2.epa.gov/sites/production/files/2014-09/documents/sciance.pdf |archive-date=2015-10-15}}</ref>

=== Land use changes ===
{{Main|Agriculture|Deforestation}}
Since the invention of agriculture, humans have directly and gradually influenced the carbon cycle over century-long timescales by modifying the mixture of vegetation in the terrestrial biosphere.<ref name=":0">{{cite book |doi=10.1016/S0070-4571(08)70338-8 |chapter=The Current Carbon Cycle and Human Impact |title=Geochemistry of Sedimentary Carbonates |series=Developments in Sedimentology |date=1990 |volume=48 |pages=447–510 |isbn=978-0-444-87391-0 |editor1-first=John W. |editor1-last=Morse |editor2-first=Fred T. |editor2-last=Mackenzie }}</ref> Over the past several centuries, direct and indirect human-caused [[land use]] and land cover change (LUCC) has led to the [[Biodiversity loss|loss of biodiversity]], which lowers ecosystems' resilience to environmental stresses and decreases their ability to remove carbon from the atmosphere. More directly, it often leads to the release of carbon from terrestrial ecosystems into the atmosphere.

Deforestation for agricultural purposes removes forests, which hold large amounts of carbon, and replaces them, generally with agricultural or urban areas. Both of these replacement land cover types store comparatively small amounts of carbon so that the net result of the transition is that more carbon stays in the atmosphere.  However, the effects on the atmosphere and overall carbon cycle can be intentionally and/or naturally reversed with [[reforestation]].{{fact|date=October 2024}}