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{{Use dmy dates|date=December 2019}} {{Use dmy dates|date=December 2019}}
]s have been identified as a possible agent for abrupt changes.]] ]s have been identified as a possible agent for abrupt changes.]]
An '''abrupt climate change''' occurs when the ] is forced to transition at a rate that is determined by the climate system ], and which is more rapid than the rate of change of the ],<ref>{{cite book|url=http://clio.columbia.edu/catalog/10283642?counter=2|title=Abrupt climate change: mechanisms, patterns, and impacts|author1=Harunur Rashid |author2=Leonid Polyak |author3=Ellen Mosley-Thompson | year = 2011|publisher=]| isbn = 9780875904849}}</ref> though it may include sudden forcing events such as ]s.<ref name=def2>{{cite book An '''abrupt climate change''' occurs when the ] is forced to transition at a rate that is determined by the climate system ]. The transition rate is more rapid than the rate of change of the ],<ref>{{cite book|url=http://clio.columbia.edu/catalog/10283642?counter=2|title=Abrupt climate change: mechanisms, patterns, and impacts|author1=Harunur Rashid |author2=Leonid Polyak |author3=Ellen Mosley-Thompson | year = 2011|publisher=]| isbn = 9780875904849}}</ref> though it may include sudden forcing events such as ]s.<ref name=def2>{{cite book
| isbn = 978-0-309-07434-6 | isbn = 978-0-309-07434-6
|author = Committee on Abrupt Climate Change, National Research Council. |author = Committee on Abrupt Climate Change, National Research Council.
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| chapter=Definition of Abrupt Climate Change | chapter=Definition of Abrupt Climate Change
| url=http://www.nap.edu/catalog.php?record_id=10136#toc|doi = 10.17226/10136 | url=http://www.nap.edu/catalog.php?record_id=10136#toc|doi = 10.17226/10136
}}</ref> Abrupt climate change therefore is a variation beyond the ]. Past events include the end of the ],<ref name="SahneyBentonFalconLang 2010RainforestCollapse">{{ cite journal | author= Sahney, S. |author2=Benton, M.J. |author3=Falcon-Lang, H.J. | year=2010 | title= Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica | journal=Geology | volume = 38 | pages = 1079–1082 | doi=10.1130/G31182.1 | issue=12|bibcode = 2010Geo....38.1079S }}</ref> ],<ref name="Broecker">{{Cite journal| author-link=Wallace Smith Broecker| last1=Broecker| first1=W. S. | title = Geology. Was the Younger Dryas triggered by a flood? | volume = 312| journal = ] | issue = 5777 | pages = 1146–1148 | date=May 2006 | issn = 0036-8075 | pmid = 16728622 | doi = 10.1126/science.1123253| s2cid=39544213}}</ref> ]s, ]s and possibly also the ].<ref>{{cite book|isbn=0-309-07434-7|author=National Research Council |year=2002|page=|publisher=National Academy Press|location=Washington, D.C.|title=Abrupt climate change : inevitable surprises|url=https://archive.org/details/abruptclimatecha00boar|url-access=registration}}</ref> The term is also used within the context of ] to describe sudden climate change that is detectable over the time-scale of a human lifetime, possibly as the result of ]<ref>{{Cite journal|first1=J. A. |first2=R. A. |first3=M. |first4=M. |first5=J. |first6=P. |last1=Rial |first7=H. |first8=N. |first9=R. |last10=Reynolds |first10=J. F. |last11=Salas |first11=J. D. |title=Nonlinearities, Feedbacks and Critical Thresholds within the Earth's Climate System |url=http://www.biology.duke.edu/upe302/pdf%20files/jfr_nonlinear.pdf |journal=Climatic Change |volume=65 |pages=11–00 |year=2004 |doi=10.1023/B:CLIM.0000037493.89489.3f |last2=Pielke Sr. |last3=Beniston |last4=Claussen |last5=Canadell |last6=Cox |last7=Held |last8=De Noblet-Ducoudré |last9=Prinn |s2cid=14173232 |url-status=dead |archive-url=https://web.archive.org/web/20130309170355/http://biology.duke.edu/upe302/pdf%20files/jfr_nonlinear.pdf |archive-date=9 March 2013 |hdl=11858/00-001M-0000-0013-A8E8-0 |hdl-access=free }}</ref> or ]. }}</ref> Abrupt climate change therefore is a variation beyond the ]. Past events include the end of the ],<ref name="SahneyBentonFalconLang 2010RainforestCollapse">{{ cite journal | author= Sahney, S. |author2=Benton, M.J. |author3=Falcon-Lang, H.J. | year=2010 | title= Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica | journal=Geology | volume = 38 | pages = 1079–1082 | doi=10.1130/G31182.1 | issue=12|bibcode = 2010Geo....38.1079S }}</ref> ],<ref name="Broecker">{{Cite journal| author-link=Wallace Smith Broecker| last1=Broecker| first1=W. S. | title = Geology. Was the Younger Dryas triggered by a flood? | volume = 312| journal = ] | issue = 5777 | pages = 1146–1148 | date=May 2006 | issn = 0036-8075 | pmid = 16728622 | doi = 10.1126/science.1123253| s2cid=39544213}}</ref> ]s, ]s and possibly also the ].<ref>{{cite book|isbn=0-309-07434-7|author=National Research Council |year=2002|page=|publisher=National Academy Press|location=Washington, D.C.|title=Abrupt climate change : inevitable surprises|url=https://archive.org/details/abruptclimatecha00boar|url-access=registration}}</ref> The term is also used within the context of ] to describe sudden climate change that is detectable over the time-scale of a human lifetime. Such a sudden climate change can be the result of ]<ref>{{Cite journal|first1=J. A. |first2=R. A. |first3=M. |first4=M. |first5=J. |first6=P. |last1=Rial |first7=H. |first8=N. |first9=R. |last10=Reynolds |first10=J. F. |last11=Salas |first11=J. D. |title=Nonlinearities, Feedbacks and Critical Thresholds within the Earth's Climate System |url=http://www.biology.duke.edu/upe302/pdf%20files/jfr_nonlinear.pdf |journal=Climatic Change |volume=65 |pages=11–00 |year=2004 |doi=10.1023/B:CLIM.0000037493.89489.3f |last2=Pielke Sr. |last3=Beniston |last4=Claussen |last5=Canadell |last6=Cox |last7=Held |last8=De Noblet-Ducoudré |last9=Prinn |s2cid=14173232 |url-status=dead |archive-url=https://web.archive.org/web/20130309170355/http://biology.duke.edu/upe302/pdf%20files/jfr_nonlinear.pdf |archive-date=9 March 2013 |hdl=11858/00-001M-0000-0013-A8E8-0 |hdl-access=free }}</ref> or ].


Scientists may use different timescales when speaking of ''abrupt events''. For example, the duration of the onset of the Paleocene–Eocene Thermal Maximum may have been anywhere between a few decades and several thousand years. In comparison, ]s predict that under ongoing ], the Earth's near surface temperature could depart from the usual range of variability in the last 150 years as early as 2047.<ref name=":1">{{cite journal |last1=Mora |first1=C |year=2013 |title=The projected timing of climate departure from recent variability |journal=Nature |volume=502 |issue=7470 |pages=183–187 |bibcode=2013Natur.502..183M |doi=10.1038/nature12540 |pmid=24108050 |s2cid=4471413}}</ref>
Timescales of events described as 'abrupt' may vary dramatically. Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming of +{{convert|10|C-change||disp=x| (+|)}} within a timescale of a few years.<ref>{{cite journal |last1=Grachev |first1=A.M. |last2=Severinghaus |first2=J.P. |title=A revised +10±4&nbsp;°C magnitude of the abrupt change in Greenland temperature at the Younger Dryas termination using published GISP2 gas isotope data and air thermal diffusion constants |journal=Quaternary Science Reviews |volume=24 |issue=5–6 |pages=513–9 |year=2005 |doi=10.1016/j.quascirev.2004.10.016|bibcode = 2005QSRv...24..513G }}</ref> Other abrupt changes are the +{{convert|4|C-change||disp=x| (+|)}} on Greenland 11,270 years ago<ref>{{cite journal |last1=Kobashi |first1=T. |last2=Severinghaus |first2=J.P. |last3=Barnola |first3=J. |title=4 ± 1.5&nbsp;°C abrupt warming 11,270 yr ago identified from trapped air in Greenland ice |journal=Earth and Planetary Science Letters |volume=268 |issue=3–4 |pages=397–407 |date=30 April 2008 |doi=10.1016/j.epsl.2008.01.032 |bibcode=2008E&PSL.268..397K}}</ref> or the abrupt +{{convert|6|C-change}} warming 22,000 years ago on ].<ref>{{cite journal |last1=Taylor |first1=K.C. |title=Abrupt climate change around 22 ka on the Siple Coast of Antarctica |journal=Quaternary Science Reviews |volume=23 |issue=1–2 |pages=7–15 |date=January 2004 |doi=10.1016/j.quascirev.2003.09.004 |last2=White |first2=J |last3=Severinghaus |first3=J |last4=Brook |first4=E |last5=Mayewski |first5=P |last6=Alley |first6=R |last7=Steig |first7=E |last8=Spencer |first8=M |last9=Meyerson |first9=E |last10=Meese |first10=D |last11=Lamorey |first11=G |last12=Grachev |first12=A |last13=Gow |first13=A |last14=Barnett |first14=B |bibcode = 2004QSRv...23....7T }}</ref> By contrast, the Paleocene-Eocene thermal maximum may have initiated anywhere between a few decades and several thousand years. Finally, ] project that under ongoing ] as early as 2047, the Earth's near surface temperature could depart from the range of variability in the last 150 years, affecting over 3 billion people and most places of great species diversity on Earth.<ref>{{cite journal |last1=Mora |first1=C |title=The projected timing of climate departure from recent variability |journal=Nature |volume=502 |issue=7470 |pages=183–187 |year=2013 |doi=10.1038/nature12540|bibcode = 2013Natur.502..183M |pmid=24108050|s2cid=4471413 }}</ref>


== Definitions == == Definitions ==
''Abrupt climate change'' can be defined in terms of physics or in terms of impacts: "In terms of physics, it is a transition of the climate system into a different mode on a time scale that is faster than the responsible forcing. In terms of impacts, an abrupt change is one that takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it. These definitions are complementary: the former gives some insight into how abrupt climate change comes about; the latter explains why there is so much research devoted to it."<ref>{{cite web |title=1: What defines "abrupt" climate change? |url=http://ocp.ldeo.columbia.edu/res/div/ocp/arch/definition.shtml |access-date=2021-07-08 |website=LAMONT-DOHERTY EARTH OBSERVATORY}}</ref>
According to the Committee on Abrupt Climate Change of the ]:<ref>{{cite web|website=LAMONT-DOHERTY EARTH OBSERVATORY|url=http://ocp.ldeo.columbia.edu/res/div/ocp/arch/definition.shtml|access-date=2021-07-08|title=1: What defines "abrupt" climate change?}}</ref>
<blockquote>
There are essentially two definitions of abrupt climate change:


=== Timescales ===
*In terms of physics, it is a ''transition of the climate system into a different mode on a time scale that is faster than the responsible forcing''.
Timescales of events described as ''abrupt'' may vary dramatically. Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming of +{{convert|10|C-change||disp=x| (+|)}} within a timescale of a few years.<ref>{{cite journal |last1=Grachev |first1=A.M. |last2=Severinghaus |first2=J.P. |year=2005 |title=A revised +10±4&nbsp;°C magnitude of the abrupt change in Greenland temperature at the Younger Dryas termination using published GISP2 gas isotope data and air thermal diffusion constants |journal=Quaternary Science Reviews |volume=24 |issue=5–6 |pages=513–9 |bibcode=2005QSRv...24..513G |doi=10.1016/j.quascirev.2004.10.016}}</ref> Other abrupt changes are the +{{convert|4|C-change||disp=x| (+|)}} on Greenland 11,270 years ago<ref>{{cite journal |last1=Kobashi |first1=T. |last2=Severinghaus |first2=J.P. |last3=Barnola |first3=J. |date=30 April 2008 |title=4 ± 1.5&nbsp;°C abrupt warming 11,270 yr ago identified from trapped air in Greenland ice |journal=Earth and Planetary Science Letters |volume=268 |issue=3–4 |pages=397–407 |bibcode=2008E&PSL.268..397K |doi=10.1016/j.epsl.2008.01.032}}</ref> or the abrupt +{{convert|6|C-change}} warming 22,000 years ago on ].<ref>{{cite journal |last1=Taylor |first1=K.C. |last2=White |first2=J |last3=Severinghaus |first3=J |last4=Brook |first4=E |last5=Mayewski |first5=P |last6=Alley |first6=R |last7=Steig |first7=E |last8=Spencer |first8=M |last9=Meyerson |first9=E |last10=Meese |first10=D |last11=Lamorey |first11=G |last12=Grachev |first12=A |last13=Gow |first13=A |last14=Barnett |first14=B |date=January 2004 |title=Abrupt climate change around 22 ka on the Siple Coast of Antarctica |journal=Quaternary Science Reviews |volume=23 |issue=1–2 |pages=7–15 |bibcode=2004QSRv...23....7T |doi=10.1016/j.quascirev.2003.09.004}}</ref>
*In terms of impacts, ''"an abrupt change is one that takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it"''.


By contrast, the Paleocene–Eocene Thermal Maximum may have initiated anywhere between a few decades and several thousand years. Finally, ] project that under ongoing ] as early as 2047, the Earth's near surface temperature could depart from the range of variability in the last 150 years.<ref name=":1" />
These definitions are complementary: the former gives some insight into how abrupt climate change comes about; the latter explains why there is so much research devoted to it.</blockquote>


== General == == Past events ==
] period of abrupt climate change is named after the ] flower, ].]]
Possible ] include regional ], some of which had abrupt onset and may therefore be regarded as abrupt climate change.<ref name=":0">{{Cite journal|last1=Lenton|first1=T. M.|last2=Held|first2=H.|last3=Kriegler|first3=E.|last4=Hall|first4=J. W.|last5=Lucht|first5=W.|last6=Rahmstorf|first6=S.|last7=Schellnhuber|first7=H. J.|year=2008|title=Inaugural Article: Tipping elements in the Earth's climate system|journal=Proceedings of the National Academy of Sciences|volume=105|issue=6|pages=1786–1793|bibcode=2008PNAS..105.1786L|doi=10.1073/pnas.0705414105|pmid=18258748|pmc=2538841|doi-access=free}}</ref> Scientists have stated, "Our synthesis of present knowledge suggests that a variety of tipping elements could reach their critical point within this century under anthropogenic climate change".<ref name=":0" />


Several periods of abrupt climate change have been identified in the ] record. Notable examples include:
It has been postulated that teleconnections -- oceanic and atmospheric processes on different timescales -- connect both hemispheres during abrupt climate change.<ref>{{cite journal|title=Global atmospheric teleconnections during Dansgaard–Oeschger events|journal=Nature Geoscience|volume=10|pages=36–40|author=Markle |display-authors=et al|publisher=Nature|year=2016|doi=10.1038/ngeo2848}}</ref>


* About 25 climate shifts, called ], which have been identified in the ] record during the glacial period over the past 100,000 years.<ref>{{Cite web |title=Heinrich and Dansgaard–Oeschger Events |url=https://www.ncdc.noaa.gov/abrupt-climate-change/Heinrich%20and%20Dansgaard%E2%80%93Oeschger%20Events |url-status=dead |archive-url=https://web.archive.org/web/20161222172123/https://www.ncdc.noaa.gov/abrupt-climate-change/Heinrich%20and%20Dansgaard%E2%80%93Oeschger%20Events |archive-date=22 December 2016 |access-date=7 August 2019 |website=National Centers for Environmental Information (NCEI) formerly known as National Climatic Data Center (NCDC) |publisher=NOAA}}</ref>
The ] that global warming "could lead to some effects that are abrupt or irreversible".<ref>{{Cite book | chapter=Summary for Policymakers | title=Climate Change 2007: Synthesis Report | chapter-url=http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf | date=17 November 2007| publisher=] }}</ref>
* The ] event, notably its sudden end. It is the most recent of the Dansgaard–Oeschger cycles and began 12,900 years ago and moved back into a warm-and-wet climate regime about 11,600 years ago.{{citation needed|date=May 2009}} It has been suggested that "the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system."<ref>{{Cite journal |last1=Alley |first1=R. B. |author1-link=Richard B. Alley |last2=Meese |first2=D. A. |last3=Shuman |first3=C. A. |last4=Gow |first4=A. J. |last5=Taylor |first5=K. C. |last6=Grootes |first6=P. M. |last7=White |first7=J. W. C. |last8=Ram |first8=M. |last9=Waddington |first9=E. D. |last10=Mayewski |first10=P. A. |last11=Zielinski |first11=G. A. |year=1993 |title=Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event |url=http://earthsciences.ucr.edu/gcec_pages/docs/Alley%20et%20al%201993-Nature-Dryas%20Snow%20Rates.pdf |url-status=dead |journal=] |volume=362 |issue=6420 |pages=527–529 |bibcode=1993Natur.362..527A |doi=10.1038/362527a0 |s2cid=4325976 |archive-url=https://web.archive.org/web/20100617090928/http://earthsciences.ucr.edu/gcec_pages/docs/Alley%20et%20al%201993-Nature-Dryas%20Snow%20Rates.pdf |archive-date=17 June 2010 |hdl=11603/24307}}</ref> A model for this event based on disruption to the ] has been supported by other studies.<ref name="cite doi|10.1038/378165a0">{{Cite journal |last1=Manabe |first1=S. |last2=Stouffer |first2=R. J. |year=1995 |title=Simulation of abrupt climate change induced by freshwater input to the North Atlantic Ocean |url=http://www.gfdl.noaa.gov/bibliography/related_files/sm9501.pdf |journal=] |volume=378 |issue=6553 |page=165 |bibcode=1995Natur.378..165M |doi=10.1038/378165a0 |s2cid=4302999}}</ref>
* The ], timed at 55 million years ago, which may have been caused by the ],<ref>{{Cite journal |last1=Farley |first1=K. A. |last2=Eltgroth |first2=S. F. |year=2003 |title=An alternative age model for the Paleocene–Eocene thermal maximum using extraterrestrial 3He |url=https://authors.library.caltech.edu/35478/2/mmc1.xls |journal=Earth and Planetary Science Letters |volume=208 |issue=3–4 |pages=135–148 |bibcode=2003E&PSL.208..135F |doi=10.1016/S0012-821X(03)00017-7}}</ref> although potential alternative mechanisms have been identified.<ref>{{Cite journal |last1=Pagani |first1=M. |last2=Caldeira |first2=K. |last3=Archer |first3=D. |last4=Zachos |first4=C. |date=Dec 2006 |title=Atmosphere. An ancient carbon mystery |journal=Science |volume=314 |issue=5805 |pages=1556–1557 |doi=10.1126/science.1136110 |issn=0036-8075 |pmid=17158314 |s2cid=128375931}}</ref> This was associated with rapid ]<ref name="ReferenceA">{{Cite journal |last1=Zachos |first1=J. C. |last2=Röhl |first2=U. |last3=Schellenberg |first3=S. A. |last4=Sluijs |first4=A. |last5=Hodell |first5=D. A. |last6=Kelly |first6=D. C. |last7=Thomas |first7=E. |last8=Nicolo |first8=M. |last9=Raffi |first9=I. |last10=Lourens |first10=L. J. |last11=McCarren |first11=H. |last12=Kroon |first12=D. |date=Jun 2005 |title=Rapid acidification of the ocean during the Paleocene–Eocene thermal maximum |journal=] |volume=308 |issue=5728 |pages=1611–1615 |bibcode=2005Sci...308.1611Z |doi=10.1126/science.1109004 |pmid=15947184 |s2cid=26909706 |hdl-access=free |hdl=1874/385806}}</ref>
* The Permian–Triassic Extinction Event, in which up to 95% of all species became extinct, has been hypothesized to be related to a rapid change in global climate.<ref>{{cite journal |last1=Benton |first1=M. J. |last2=Twitchet |first2=R. J. |year=2003 |title=How to kill (almost) all life: the end-Permian extinction event |url=http://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdf |url-status=dead |journal=Trends in Ecology & Evolution |volume=18 |issue=7 |pages=358–365 |doi=10.1016/S0169-5347(03)00093-4 |archive-url=https://wayback.archive-it.org/all/20070418023344/http://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdf |archive-date=18 April 2007}}</ref><ref name="crowley">{{Cite journal |last1=Crowley |first1=T. J. |last2=North |first2=G. R. |author2-link=Gerald North |date=May 1988 |title=Abrupt Climate Change and Extinction Events in Earth History |journal=] |volume=240 |issue=4855 |pages=996–1002 |bibcode=1988Sci...240..996C |doi=10.1126/science.240.4855.996 |pmid=17731712 |s2cid=44921662}}</ref> Life on land took 30 million years to recover.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{cite journal |author1=Sahney, S. |author2=Benton, M.J. |year=2008 |title=Recovery from the most profound mass extinction of all time |journal=Proceedings of the Royal Society B |volume=275 |issue=1636 |pages=759–65 |doi=10.1098/rspb.2007.1370 |pmc=2596898 |pmid=18198148}}</ref>
* The ] occurred 300 million years ago, at which time tropical rainforests were devastated by climate change. The cooler, drier climate had a severe effect on the biodiversity of amphibians, the primary form of vertebrate life on land.<ref name="SahneyBentonFalconLang 2010RainforestCollapse" />


There are also abrupt climate changes associated with the catastrophic draining of glacial lakes. One example of this is the ], which is associated with the draining of ].<ref>{{Cite journal |last1=Alley |first1=R. B. |author1-link=Richard B. Alley |last2=Mayewski |first2=P. A. |last3=Sowers |first3=T. |last4=Stuiver |first4=M. |last5=Taylor |first5=K. C. |last6=Clark |first6=P. U. |year=1997 |title=Holocene climatic instability: A prominent, widespread event 8200 yr ago |journal=Geology |volume=25 |issue=6 |page=483 |bibcode=1997Geo....25..483A |doi=10.1130/0091-7613(1997)025<0483:HCIAPW>2.3.CO;2}}</ref> Another example is the ], c. 14,500 years before present (]), which is believed to have been caused by a meltwater pulse probably from either the ]<ref>{{Cite journal |author=Weber |author2=Clark |author3=Kuhn |author4=Timmermann |author-link4=Axel Timmermann |date=5 June 2014 |title=Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation |journal=Nature |volume=510 |issue=7503 |pages=134–138 |bibcode=2014Natur.510..134W |doi=10.1038/nature13397 |pmid=24870232 |s2cid=205238911}}</ref> or the ].<ref>{{Cite journal |last=Gregoire |first=Lauren |date=11 July 2012 |title=Deglacial rapid sea level rises caused by ice-sheet saddle collapses |url=http://eprints.whiterose.ac.uk/76493/8/gregoirel1.pdf |journal=Nature |volume=487 |issue=7406 |pages=219–222 |bibcode=2012Natur.487..219G |doi=10.1038/nature11257 |pmid=22785319 |s2cid=4403135}}</ref> These rapid meltwater release events have been hypothesized as a cause for Dansgaard–Oeschger cycles.<ref>{{cite book |author=Bond, G.C. |title=Mechanisms of Global Change at Millennial Time Scales |author2=Showers, W. |author3=Elliot, M. |author4=Evans, M. |author5=Lotti, R. |author6=Hajdas, I. |author7=Bonani, G. |author8=Johnson, S. |publisher=American Geophysical Union, Washington DC |year=1999 |isbn=0-87590-033-X |editor=Clark, P.U. |series=Geophysical Monograph |pages=59–76 |chapter=The North Atlantic's 1–2 kyr climate rhythm: relation to Heinrich events, Dansgaard/Oeschger cycles and the little ice age |editor2=Webb, R.S. |editor3=Keigwin, L.D. |chapter-url=http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al%201999%20%20N.%20Atlantic%201-2.PDF |archive-url=https://web.archive.org/web/20081029174737/http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al%201999%20%20N.%20Atlantic%201-2.PDF |archive-date=29 October 2008 |url-status=dead |issue=112}}</ref>
A 2013 report from the U.S. ] called for attention to the abrupt impacts of climate change, stating that even steady, gradual change in the physical climate system can have abrupt impacts elsewhere, such as in human infrastructure and ecosystems if critical thresholds are crossed. The report emphasizes the need for an early warning system that could help society better anticipate sudden changes and emerging impacts.<ref>{{cite web|url=http://dels.nas.edu/Report/Report/18373|title=Abrupt Impacts of Climate Change: Anticipating Surprises|last=Board on Atmospheric Sciences and Climate|date=2013|access-date=12 December 2013|archive-date=13 October 2017|archive-url=https://web.archive.org/web/20171013020148/http://dels.nas.edu/Report/Report/18373|url-status=dead}}</ref>


A five-year study led by the ] and additionally conducted by ], ], the ], and the ]<ref>{{cite news |title=Research wins environmental grant |url=https://www.oxfordmail.co.uk/news/1566130.research-wins-environmental-grant/ |agency=Oxford Mail |publisher=Newsquest |date=23 July 2007 |language=en}}</ref> completed in 2013 called "Response of Humans to Abrupt Environmental Transitions" and referred to as "RESET" aimed to see if the hypothesis that humans have major development shifts during or immediately after abrupt climate changes with the aid of knowledge pulled from research on the palaeoenvironmental conditions, prehistoric archaeological history, oceanography, and volcanic geology of the last 130,000 years and across continents.<ref>{{cite web |title=RESET: RESponse of humans to abrupt Environmental Transitions |url=https://gtr.ukri.org/projects?ref=NE%2FE015670%2F1 |website=gtr.ukri.org |publisher=UK Research and Innovation}}</ref><ref>{{cite web |title=RESET |url=https://c14.arch.ox.ac.uk/reset/index.html |publisher=Oxford University}}</ref> It also aimed to predict possible human behavior in the event of climate change, and the timing of climate change.<ref>{{cite web |title=RESET - Response of Humans to Abrupt Environmental Transitions - School of Archaeology - University of Oxford |url=https://projects.arch.ox.ac.uk/REST.html |website=projects.arch.ox.ac.uk |publisher=Oxford School of Archaeology}}</ref>
A characteristic of the abrupt climate change impacts is that they occur at a rate that is faster than anticipated. This element makes ecosystems that are immobile and limited in their capacity to respond to abrupt changes, such as forestry ecosystems, particularly vulnerable.<ref>{{Cite journal |last1=Bengston |first1=David N. |last2=Crabtree |first2=Jason |last3=Hujala |first3=Teppo |date=2020-12-01 |title=Abrupt climate change: Exploring the implications of a wild card |url=https://www.sciencedirect.com/science/article/pii/S0016328720301312 |journal=Futures |language=en |volume=124 |pages=102641 |doi=10.1016/j.futures.2020.102641 |s2cid=224860967 |issn=0016-3287}}</ref>


A 2017 study concluded that similar conditions to today's ] (atmospheric circulation and hydroclimate changes), ~17,700 years ago, when stratospheric ozone depletion contributed to abrupt accelerated Southern Hemisphere ]. The event coincidentally happened with an estimated 192-year series of massive volcanic eruptions, attributed to ] in ].<ref>{{cite journal |author=McConnell |display-authors=et al |year=2017 |title=Synchronous volcanic eruptions and abrupt climate change ~17.7 ka plausibly linked by stratospheric ozone depletion |journal=Proceedings of the National Academy of Sciences |publisher=PNAS |volume=114 |issue=38 |pages=10035–10040 |bibcode=2017PNAS..11410035M |doi=10.1073/pnas.1705595114 |pmc=5617275 |pmid=28874529 |doi-access=free}}</ref>
The probability of abrupt change for some climate related feedbacks may be low.<ref name="ccsp abrupt climate change">
{{Cite book
| author=Clark, P.U.| date=December 2008
| chapter=Executive Summary
| title=Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research
| chapter-url=http://www.globalchange.gov/browse/reports/sap-34-abrupt-climate-change
| publisher=U.S. Geological Survey
| location=Reston, Virginia
|display-authors=etal |pages=1–7}}
</ref><ref name="tar large scale impacts">{{Cite book
| author=IPCC
| chapter=Summary for Policymakers
| chapter-url=http://www.grida.no/climate/ipcc_tar/wg2/005.htm
| url=http://www.grida.no/climate/ipcc_tar/wg2/009.htm
| title=Sec. 2.6. The Potential for Large-Scale and Possibly Irreversible Impacts Poses Risks that have yet to be Reliably Quantified
| access-date=10 May 2018
| archive-date=24 September 2015
| archive-url=https://web.archive.org/web/20150924041011/http://www.grida.no/climate/ipcc_tar/wg2/009.htm
| url-status=dead
}}</ref> Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly and warming that is sustained over longer time periods.<ref name="tar large scale impacts"/>

===Climate models===
{{Main|Climate model}}
<!-- Determine if this is actually current, then replace the article text after this comment with: "As of , climate models are not yet able to predict ... ".
Example:
"As of 2021, climate models are not yet able to predict abrupt climate change events, or most of the past abrupt climate shifts."
Use the {{as of}} template for "As of ".
-->Climate models are currently{{When|date=February 2021}} unable to predict abrupt climate change events, or most of the past abrupt climate shifts.<ref name="Mayewski2016">{{cite journal|bibcode=2016EGUGA..18.2567M|title=Abrupt climate change: Past, present and the search for precursors as an aid to predicting events in the future (Hans Oeschger Medal Lecture)|journal=EGU General Assembly Conference Abstracts|volume=18|pages=EPSC2016-2567|year=2016|author=Mayewski, Paul Andrew}}</ref> A potential abrupt feedback due to ] lake formations in the Arctic, in response to thawing ] soils, releasing additional greenhouse gas methane, is currently not accounted for in climate models.<ref>{{cite web|url=https://www.nasa.gov/feature/goddard/2018/unexpected-future-boost-of-methane-possible-from-arctic-permafrost|title=Unexpected Future Boost of Methane Possible from Arctic Permafrost|year=2018|work=NASA}}</ref>


==Possible precursor== == Possible precursors ==
Most abrupt climate shifts are likely due to sudden circulation shifts, analogous to a flood cutting a new river channel. The best-known examples are the several dozen shutdowns of the ]'s ] during the last ], affecting climate worldwide.<ref name="Alley2002">{{cite journal | title = Abrupt Climate Change | url = http://www.unice.fr/coquillard/UE36/Science-2003-Alley-2005-10.pdf | first11 = J. M. | last11 = Wallace | journal = ] | volume = 299 | issue = 5615 | pages = 2005–2010 | first10 = L. D. | date=Mar 2003 | doi = 10.1126/science.1081056 | pmid=12663908 |bibcode = 2003Sci...299.2005A | last1 = Alley | first1 = R. B. | last2 = Marotzke | last10 = Talley | first2 = J. | last3 = Nordhaus | first3 = W. D. | last4 = Overpeck | first4 = J. T. | last5 = Peteet | first5 = D. M. | last6 = Pielke Jr | first6 = R. A. | last7 = Pierrehumbert | first7 = R. T. | last8 = Rhines | first8 = P. B. | last9 = Stocker | first9 = T. F. | s2cid = 19455675 }}</ref> Most abrupt climate shifts are likely due to sudden circulation shifts, analogous to a flood cutting a new river channel. The best-known examples are the several dozen shutdowns of the ]'s ] during the last ], affecting climate worldwide.<ref name="Alley2002">{{cite journal | title = Abrupt Climate Change | url = http://www.unice.fr/coquillard/UE36/Science-2003-Alley-2005-10.pdf | first11 = J. M. | last11 = Wallace | journal = ] | volume = 299 | issue = 5615 | pages = 2005–2010 | first10 = L. D. | date=Mar 2003 | doi = 10.1126/science.1081056 | pmid=12663908 |bibcode = 2003Sci...299.2005A | last1 = Alley | first1 = R. B. | last2 = Marotzke | last10 = Talley | first2 = J. | last3 = Nordhaus | first3 = W. D. | last4 = Overpeck | first4 = J. T. | last5 = Peteet | first5 = D. M. | last6 = Pielke Jr | first6 = R. A. | last7 = Pierrehumbert | first7 = R. T. | last8 = Rhines | first8 = P. B. | last9 = Stocker | first9 = T. F. | s2cid = 19455675 }}</ref>


*The ], the duration of the summer season, is considered abrupt and massive.<ref name="Mayewski2016" /> * The ], the duration of the summer season, is considered abrupt and massive.<ref name="Mayewski2016">{{cite journal |author=Mayewski, Paul Andrew |year=2016 |title=Abrupt climate change: Past, present and the search for precursors as an aid to predicting events in the future (Hans Oeschger Medal Lecture) |journal=EGU General Assembly Conference Abstracts |volume=18 |pages=EPSC2016-2567 |bibcode=2016EGUGA..18.2567M}}</ref>
*Antarctic ozone depletion caused significant atmospheric circulation changes.<ref name="Mayewski2016" /> * Antarctic ozone depletion caused significant atmospheric circulation changes.<ref name="Mayewski2016" />
*There have also been two occasions when the Atlantic's Meridional Overturning Circulation lost a crucial safety factor. The ] flushing at 75&nbsp;°N shut down in 1978, recovering over the next decade.<ref>{{cite journal | year=1991 |vauthors=Schlosser P, Bönisch G, Rhein M, Bayer R |title=Reduction of deepwater formation in the Greenland Sea during the 1980s: Evidence from tracer data |volume=251 |pages=1054–1056 |journal=Science | doi=10.1126/science.251.4997.1054 | pmid=17802088 | issue=4997 |bibcode = 1991Sci...251.1054S |s2cid=21374638 }}</ref> Then the second-largest flushing site, the ], shut down in 1997<ref>{{Cite journal| doi = 10.1256/wea.223.05| title = Sub-Arctic oceans and global climate| year = 2006| last1 = Rhines | first1 = P. B.| journal = Weather| volume = 61| issue = 4| pages = 109–118|bibcode = 2006Wthr...61..109R | doi-access = free}}</ref> for ten years.<ref>{{Cite journal| doi = 10.1038/ngeo382| title = Surprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007–2008| year = 2008| last1 = Våge | first1 = K.| last2 = Pickart | first2 = R. S.| last3 = Thierry | first3 = V.| last4 = Reverdin | first4 = G.| last5 = Lee | first5 = C. M.| last6 = Petrie | first6 = B.| last7 = Agnew | first7 = T. A.| last8 = Wong | first8 = A.| last9 = Ribergaard | first9 = M. H.| journal = Nature Geoscience| volume = 2| issue = 1| page = 67|bibcode = 2009NatGe...2...67V | url = https://archimer.ifremer.fr/doc/00000/6415/}}</ref> While shutdowns overlapping in time have not been seen during the 50 years of observation, previous total shutdowns had severe worldwide climate consequences.<ref name="Alley2002" /> * There have also been two occasions when the Atlantic's Meridional Overturning Circulation lost a crucial safety factor. The ] flushing at 75&nbsp;°N shut down in 1978, recovering over the next decade.<ref>{{cite journal | year=1991 |vauthors=Schlosser P, Bönisch G, Rhein M, Bayer R |title=Reduction of deepwater formation in the Greenland Sea during the 1980s: Evidence from tracer data |volume=251 |pages=1054–1056 |journal=Science | doi=10.1126/science.251.4997.1054 | pmid=17802088 | issue=4997 |bibcode = 1991Sci...251.1054S |s2cid=21374638 }}</ref> Then the second-largest flushing site, the ], shut down in 1997<ref>{{Cite journal| doi = 10.1256/wea.223.05| title = Sub-Arctic oceans and global climate| year = 2006| last1 = Rhines | first1 = P. B.| journal = Weather| volume = 61| issue = 4| pages = 109–118|bibcode = 2006Wthr...61..109R | doi-access = free}}</ref> for ten years.<ref>{{Cite journal| doi = 10.1038/ngeo382| title = Surprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007–2008| year = 2008| last1 = Våge | first1 = K.| last2 = Pickart | first2 = R. S.| last3 = Thierry | first3 = V.| last4 = Reverdin | first4 = G.| last5 = Lee | first5 = C. M.| last6 = Petrie | first6 = B.| last7 = Agnew | first7 = T. A.| last8 = Wong | first8 = A.| last9 = Ribergaard | first9 = M. H.| journal = Nature Geoscience| volume = 2| issue = 1| page = 67|bibcode = 2009NatGe...2...67V | url = https://archimer.ifremer.fr/doc/00000/6415/| hdl = 1912/2840| hdl-access = free}}</ref> While shutdowns overlapping in time have not been seen during the 50 years of observation, previous total shutdowns had severe worldwide climate consequences.<ref name="Alley2002" />
It has been postulated that teleconnections – oceanic and atmospheric processes on different timescales – connect both hemispheres during abrupt climate change.<ref>{{cite journal |author=Markle |display-authors=et al |year=2016 |title=Global atmospheric teleconnections during Dansgaard–Oeschger events |journal=Nature Geoscience |publisher=Nature |volume=10 |pages=36–40 |doi=10.1038/ngeo2848}}</ref>

== Effects ==
]. Blue paths represent deep-water currents, and red paths represent surface currents.|thumb|right]]
].|thumb|right]]

Abrupt climate change has likely been the cause of wide-ranging and severe effects:
*] in the past, most notably the ] (often referred colloquially to as the Great Dying) and the ], have been suggested as a consequence of abrupt climate change.<ref name="SahneyBentonFalconLang 2010RainforestCollapse"/><ref name="SahneyBenton2008RecoveryFromProfoundExtinction" /><ref name = crowley>{{Cite journal| first1=T. J. | first2=G. R.| last2=North| author2-link=Gerald North| journal = ]| last1=Crowley| title = Abrupt Climate Change and Extinction Events in Earth History| volume = 240| issue = 4855| pages = 996–1002| date=May 1988 | pmid = 17731712| doi = 10.1126/science.240.4855.996|bibcode = 1988Sci...240..996C | s2cid=44921662}}</ref>
*]: without interference from abrupt climate change and other extinction events, the biodiversity of Earth would continue to grow.<ref name="SahneyBentonFerry2010LinksDiversityVertebrates">{{cite journal | author=Sahney, S. | author2=Benton, M.J. | author3=Ferry, P.A. | year=2010 | title=Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land | journal=Biology Letters | doi=10.1098/rsbl.2009.1024 | volume=6 | pages=544–547 | issue=4 | pmid=20106856 | pmc=2936204 }}</ref>
* Changes in ] such as:
:* Increasing frequency of ] events<ref>{{Cite journal|first1=K. E. |author1-link=Kevin E. Trenberth |last2=Hoar |first2=T. J. |last1=Trenberth |title=El Niño and climate change |journal=] |volume=24 |issue=23 |pages=3057–3060 |year=1997 |doi=10.1029/97GL03092 |bibcode=1997GeoRL..24.3057T |doi-access=free }}</ref><ref>{{Cite journal| first1=G. A.| last2=Washington| first2=W. M.| last1=Meehl| title = El Niño-like climate change in a model with increased atmospheric CO2 concentrations| journal = ]| volume = 382| pages = 56–60| year = 1996| doi = 10.1038/382056a0|bibcode = 1996Natur.382...56M | issue=6586| s2cid=4234225| url=https://zenodo.org/record/1233184}}</ref>
:* Potential disruption to the ], such as that which may have occurred during the ] event.<ref>{{Cite journal|first1=W. S. |title=Thermohaline Circulation, the Achilles Heel of Our Climate System: Will Man-Made CO<sub>2</sub> Upset the Current Balance? |url=http://www.ldeo.columbia.edu/res/pi/arch/docs/broecker_1997.pdf |journal=] |last1=Broecker |volume=278 |year=1997 |doi=10.1126/science.278.5343.1582 |pmid=9374450 |author-link=Wallace Smith Broecker |pages=1582–1588 |bibcode=1997Sci...278.1582B |issue=5343 |url-status=dead |archive-url=https://web.archive.org/web/20091122154415/http://www.ldeo.columbia.edu/res/pi/arch/docs/broecker_1997.pdf |archive-date=22 November 2009 }}</ref><ref name="cite doi|10.1038/378165a0">{{Cite journal| first1=S.| last2=Stouffer| first2=R. J.| url=http://www.gfdl.noaa.gov/bibliography/related_files/sm9501.pdf| last1=Manabe| title = Simulation of abrupt climate change induced by freshwater input to the North Atlantic Ocean| journal = ]| volume = 378| page = 165| year = 1995| doi = 10.1038/378165a0|bibcode = 1995Natur.378..165M | issue=6553| s2cid=4302999}}</ref>
:* Changes to the ]<ref>{{Cite journal| first1=M.| last2=Jungo| first2=P.| url=http://doc.rero.ch/lm.php?url=1000,43,2,20050718135259-QT/1_bensiton_sdp.pdf| last1=Beniston| title = Shifts in the distributions of pressure, temperature and moisture and changes in the typical weather patterns in the Alpine region in response to the behavior of the North Atlantic Oscillation| journal = Theoretical and Applied Climatology| volume = 71| issue=1–2| pages = 29–42| year = 2002| doi = 10.1007/s704-002-8206-7|bibcode = 2002ThApC..71...29B | s2cid=14659582}}</ref>
:* Changes in ] (AMOC) which could contribute to more severe weather events.<ref>{{cite journal|url=http://www.atmos-chem-phys-discuss.net/acp-2015-432/|title=Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2&nbsp;°C global warming is highly dangerous|year=2015 |author1=J. Hansen |author2=M. Sato |author3=P. Hearty |author4=R. Ruedy |author5=M. Kelley |author6=V. Masson-Delmotte |author7=G. Russell |author8=G. Tselioudis |author9=J. Cao |author10=E. Rignot |author11=I. Velicogna |author12=E. Kandiano |author13=K. von Schuckmann |author14=P. Kharecha |author15=A. N. Legrande |author16=M. Bauer |author17=K.-W. Lo |display-authors=4|doi=10.5194/acpd-15-20059-2015|volume=15|issue=14|journal=Atmospheric Chemistry and Physics Discussions|pages=20059–20179|quote=Our results at least imply that strong cooling in the North Atlantic from AMOC shutdown does create higher wind speed. * * * The increment in seasonal mean wind speed of the northeasterlies relative to preindustrial conditions is as much as 10–20%. Such a percentage increase of wind speed in a storm translates into an increase of storm power dissipation by a factor ~1.4–2, because wind power dissipation is proportional to the cube of wind speed. However, our simulated changes refer to seasonal mean winds averaged over large grid-boxes, not individual storms.* * * Many of the most memorable and devastating storms in eastern North America and western Europe, popularly known as superstorms, have been winter cyclonic storms, though sometimes occurring in late fall or early spring, that generate near-hurricane-force winds and often large amounts of snowfall. Continued warming of low latitude oceans in coming decades will provide more water vapor to strengthen such storms. If this tropical warming is combined with a cooler North Atlantic Ocean from AMOC slowdown and an increase in midlatitude eddy energy, we can anticipate more severe baroclinic storms.
|bibcode=2015ACPD...1520059H|doi-access=free }}</ref>


== Climate feedback effects == == Climate feedback effects ==
] ]
{{See also|Climate change feedback|Tipping points in the climate system}} {{See also|Climate change feedback|Tipping points in the climate system}}
One source of abrupt climate change effects is a ] process, in which a warming event causes a change that adds to further warming.<ref>{{Cite journal|last1=Lenton|first1=Timothy M.|last2=Rockström|first2=Johan|last3=Gaffney|first3=Owen|last4=Rahmstorf|first4=Stefan|last5=Richardson|first5=Katherine|last6=Steffen|first6=Will|last7=Schellnhuber|first7=Hans Joachim|date=27 November 2019|title=Climate tipping points – too risky to bet against|journal=Nature|language=en|volume=575|issue=7784|pages=592–595|doi=10.1038/d41586-019-03595-0|bibcode=2019Natur.575..592L|pmid=31776487|doi-access=free}}</ref> The same can apply to cooling. Examples of such feedback processes are: One source of abrupt climate change effects is a ] process, in which a warming event causes a change that adds to further warming.<ref>{{Cite journal|last1=Lenton|first1=Timothy M.|last2=Rockström|first2=Johan|last3=Gaffney|first3=Owen|last4=Rahmstorf|first4=Stefan|last5=Richardson|first5=Katherine|last6=Steffen|first6=Will|last7=Schellnhuber|first7=Hans Joachim|date=27 November 2019|title=Climate tipping points – too risky to bet against|journal=Nature|language=en|volume=575|issue=7784|pages=592–595|doi=10.1038/d41586-019-03595-0|bibcode=2019Natur.575..592L|pmid=31776487|doi-access=free|hdl=10871/40141|hdl-access=free}}</ref> The same can apply to cooling. Examples of such feedback processes are:


*] in which the advance or retreat of ice cover alters the ] ("whiteness") of the earth and its ability to absorb the sun's energy.<ref>{{Cite journal|last1=Comiso |first1=J. C. |title=A rapidly declining perennial sea ice cover in the Arctic |journal=Geophysical Research Letters |volume=29 |issue=20 |pages=17-1–17-4 |year=2002 |doi=10.1029/2002GL015650 |bibcode=2002GeoRL..29.1956C |doi-access=free }}</ref> * ] in which the advance or retreat of ice cover alters the ] ("whiteness") of the earth and its ability to absorb the sun's energy.<ref>{{Cite journal|last1=Comiso |first1=J. C. |title=A rapidly declining perennial sea ice cover in the Arctic |journal=Geophysical Research Letters |volume=29 |issue=20 |pages=17-1–17-4 |year=2002 |doi=10.1029/2002GL015650 |bibcode=2002GeoRL..29.1956C |doi-access=free }}</ref>
*] is the release of carbon from soils in response to global warming. * ] is the release of carbon from soils in response to global warming.
* The dying and the burning of forests by ].<ref>{{Cite journal| title = Special Feature: Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest| url=http://www.pnas.org/content/early/2009/02/12/0804619106.full.pdf| journal = ]| volume = 106| issue = 49| pages = 20610–20615| date=Feb 2009 | issn=0027-8424| pmid = 19218454| doi = 10.1073/pnas.0804619106| pmc = 2791614|bibcode = 2009PNAS..10620610M| last1 = Malhi | first1 = Y.| last2 = Aragao | first2 = L. E. O. C.| last3 = Galbraith | first3 = D.| last4 = Huntingford | first4 = C.| last5 = Fisher | first5 = R.| last6 = Zelazowski | first6 = P.| last7 = Sitch | first7 = S.| last8 = McSweeney | first8 = C.| last9 = Meir | first9 = P. | doi-access=free}}</ref> * The dying and the burning of forests by ].<ref>{{Cite journal| title = Special Feature: Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest| url=http://www.pnas.org/content/early/2009/02/12/0804619106.full.pdf| journal = ]| volume = 106| issue = 49| pages = 20610–20615| date=Feb 2009 | issn=0027-8424| pmid = 19218454| doi = 10.1073/pnas.0804619106| pmc = 2791614|bibcode = 2009PNAS..10620610M| last1 = Malhi | first1 = Y.| last2 = Aragao | first2 = L. E. O. C.| last3 = Galbraith | first3 = D.| last4 = Huntingford | first4 = C.| last5 = Fisher | first5 = R.| last6 = Zelazowski | first6 = P.| last7 = Sitch | first7 = S.| last8 = McSweeney | first8 = C.| last9 = Meir | first9 = P. | doi-access=free}}</ref>
The probability of abrupt change for some climate related feedbacks may be low.<ref name="ccsp abrupt climate change">
{{Cite book |author=Clark, P.U. |title=Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research |date=December 2008 |publisher=U.S. Geological Survey |location=Reston, Virginia |pages=1–7 |chapter=Executive Summary |display-authors=etal |chapter-url=http://www.globalchange.gov/browse/reports/sap-34-abrupt-climate-change}}
</ref><ref name="tar large scale impacts">{{Cite book |author=IPCC |url=http://www.grida.no/climate/ipcc_tar/wg2/009.htm |title=Sec. 2.6. The Potential for Large-Scale and Possibly Irreversible Impacts Poses Risks that have yet to be Reliably Quantified |chapter=Summary for Policymakers |access-date=10 May 2018 |chapter-url=http://www.grida.no/climate/ipcc_tar/wg2/005.htm |archive-url=https://web.archive.org/web/20150924041011/http://www.grida.no/climate/ipcc_tar/wg2/009.htm |archive-date=24 September 2015 |url-status=dead}}</ref> Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly and warming that is sustained over longer time periods.<ref name="tar large scale impacts" />


=== Tipping points in the climate system ===
===Volcanism===
Possible ] include regional ], some of which had abrupt onset and may therefore be regarded as abrupt climate change.<ref name=":0">{{Cite journal |last1=Lenton |first1=T. M. |last2=Held |first2=H. |last3=Kriegler |first3=E. |last4=Hall |first4=J. W. |last5=Lucht |first5=W. |last6=Rahmstorf |first6=S. |last7=Schellnhuber |first7=H. J. |year=2008 |title=Inaugural Article: Tipping elements in the Earth's climate system |journal=Proceedings of the National Academy of Sciences |volume=105 |issue=6 |pages=1786–1793 |bibcode=2008PNAS..105.1786L |doi=10.1073/pnas.0705414105 |pmc=2538841 |pmid=18258748 |doi-access=free}}</ref> Scientists have stated, "Our synthesis of present knowledge suggests that a variety of tipping elements could reach their critical point within this century under anthropogenic climate change".<ref name=":0" />{{excerpt|Tipping points in the climate system|paragraphs=1|file=no}}
] in response to glacier retreat (unloading) and increased local salinity have been attributed to increased volcanic activity at the onset of the abrupt ]. They are associated with the interval of intense volcanic activity, hinting at an interaction between climate and volcanism: enhanced short-term melting of glaciers, possibly via albedo changes from particle fallout on glacier surfaces.<ref>{{Cite journal |last1=Praetorius |first1=Summer |last2=Mix |first2=Alan |last3=Jensen |first3=Britta |last4=Froese |first4=Duane |last5=Milne |first5=Glenn |last6=Wolhowe |first6=Matthew |last7=Addison |first7=Jason |last8=Prahl |first8=Fredrick |date=October 2016 |title=Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation |journal=Earth and Planetary Science Letters |volume=452 |pages=79–89 |doi=10.1016/j.epsl.2016.07.033|bibcode=2016E&PSL.452...79P }}</ref>


== Past events == === Volcanism ===
] in response to glacier retreat (unloading) and increased local salinity have been attributed to increased volcanic activity at the onset of the abrupt ]. They are associated with the interval of intense volcanic activity, hinting at an interaction between climate and volcanism: enhanced short-term melting of glaciers, possibly via albedo changes from particle fallout on glacier surfaces.<ref>{{Cite journal |last1=Praetorius |first1=Summer |last2=Mix |first2=Alan |last3=Jensen |first3=Britta |last4=Froese |first4=Duane |last5=Milne |first5=Glenn |last6=Wolhowe |first6=Matthew |last7=Addison |first7=Jason |last8=Prahl |first8=Fredrick |date=October 2016 |title=Interaction between climate, volcanism, and isostatic rebound in Southeast Alaska during the last deglaciation |journal=Earth and Planetary Science Letters |volume=452 |pages=79–89 |doi=10.1016/j.epsl.2016.07.033|bibcode=2016E&PSL.452...79P }}</ref>
] period of abrupt climate change is named after the ] flower, ].]]


== Impacts ==
Several periods of abrupt climate change have been identified in the ] record. Notable examples include:
]. Blue paths represent deep-water currents, and red paths represent surface currents.|thumb|right]]

].|thumb|right]]
* About 25 climate shifts, called ], which have been identified in the ] record during the glacial period over the past 100,000 years.<ref>{{Cite web |url=https://www.ncdc.noaa.gov/abrupt-climate-change/Heinrich%20and%20Dansgaard%E2%80%93Oeschger%20Events |title=Heinrich and Dansgaard–Oeschger Events |website=National Centers for Environmental Information (NCEI) formerly known as National Climatic Data Center (NCDC) |publisher=NOAA |access-date=7 August 2019 |archive-date=22 December 2016 |archive-url=https://web.archive.org/web/20161222172123/https://www.ncdc.noaa.gov/abrupt-climate-change/Heinrich%20and%20Dansgaard%E2%80%93Oeschger%20Events |url-status=dead }}</ref>
* The ] event, notably its sudden end. It is the most recent of the Dansgaard-Oeschger cycles and began 12,900 years ago and moved back into a warm-and-wet climate regime about 11,600 years ago.{{citation needed|date=May 2009}} It has been suggested that "the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system."<ref>{{Cite journal|last8=Ram |last2=Meese |first1=R. B. |last7=White |author1-link=Richard B. Alley |last1=Alley |last3=Shuman |first2=D. A. |first3=C. A. |last6=Grootes |first4=A. J. |last4=Gow |first5=K. C. |last9=Waddington |last5=Taylor |first6=P. M. |first7=J. W. C. |first8=M. |first9=E. D. |last10=Mayewski |first10=P. A. |last11=Zielinski |first11=G. A. |title=Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event |url=http://earthsciences.ucr.edu/gcec_pages/docs/Alley%20et%20al%201993-Nature-Dryas%20Snow%20Rates.pdf |journal=] |volume=362 |issue=6420 |pages=527–529 |year=1993 |doi=10.1038/362527a0 |bibcode=1993Natur.362..527A |hdl=11603/24307 |s2cid=4325976 |url-status=dead |archive-url=https://web.archive.org/web/20100617090928/http://earthsciences.ucr.edu/gcec_pages/docs/Alley%20et%20al%201993-Nature-Dryas%20Snow%20Rates.pdf |archive-date=17 June 2010 }}</ref> A model for this event based on disruption to the ] has been supported by other studies.<ref name="cite doi|10.1038/378165a0"/>
* The ], timed at 55 million years ago, which may have been caused by the ],<ref>{{Cite journal| first1 = K. A.| first2 = S. F.| title = An alternative age model for the Paleocene–Eocene thermal maximum using extraterrestrial 3He| last1 = Farley| journal = Earth and Planetary Science Letters| volume = 208| issue = 3–4| pages = 135–148| year = 2003| doi = 10.1016/S0012-821X(03)00017-7| last2 = Eltgroth| bibcode=2003E&PSL.208..135F| url = https://authors.library.caltech.edu/35478/2/mmc1.xls}}</ref> although potential alternative mechanisms have been identified.<ref>{{Cite journal| last3 = Archer | first1 = M. | first2 = K.| last2 = Caldeira| first3 = D. | first4 = C.| title = Atmosphere. An ancient carbon mystery| last1 = Pagani| journal = Science| last4 = Zachos| volume = 314| issue = 5805| pages = 1556–1557| date=Dec 2006 | issn = 0036-8075| pmid = 17158314| doi = 10.1126/science.1136110| s2cid = 128375931 }}</ref> This was associated with rapid ]<ref name="ReferenceA">{{Cite journal| first1=J. C.| last2=Röhl | first2=U.| last4=Sluijs| last3=Schellenberg| last5=Hodell | first3=S. A. | first4=A.| last7=Thomas| last8=Nicolo | first5=D. A.| last1=Zachos| last9=Raffi | first6=D. C.| last6=Kelly | first7=E. | first8=M. | first9=I.| title = Rapid acidification of the ocean during the Paleocene-Eocene thermal maximum | first12=D.| journal = ]| last12=Kroon| volume = 308 | first11=H.| issue = 5728| last10=Lourens| pages = 1611–1615| last11=McCarren| date=Jun 2005 | doi = 10.1126/science.1109004 | first10 = L. J.| pmid = 15947184|bibcode = 2005Sci...308.1611Z | hdl=1874/385806 | s2cid=26909706 | hdl-access=free}}</ref>
* The Permian–Triassic Extinction Event, in which up to 95% of all species became extinct, has been hypothesized to be related to a rapid change in global climate.<ref>{{cite journal | first1 = M. J. | first2 = R. J. | last2 = Twitchet | title = How to kill (almost) all life: the end-Permian extinction event | last1 = Benton | url = http://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdf | journal = Trends in Ecology & Evolution | volume = 18 | issue = 7 | pages = 358–365 | year = 2003 | doi = 10.1016/S0169-5347(03)00093-4 | archive-url = https://wayback.archive-it.org/all/20070418023344/http://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdf | archive-date = 18 April 2007 | url-status = dead }}</ref><ref name="crowley" /> Life on land took 30 million years to recover.<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{cite journal |author1=Sahney, S. |author2=Benton, M.J. | year=2008 | title=Recovery from the most profound mass extinction of all time | journal=Proceedings of the Royal Society B | doi= 10.1098/rspb.2007.1370 | volume = 275 | pages = 759–65 | pmid=18198148 | issue=1636 | pmc=2596898}}</ref>
* The ] occurred 300 million years ago, at which time tropical rainforests were devastated by climate change. The cooler, drier climate had a severe effect on the biodiversity of amphibians, the primary form of vertebrate life on land.<ref name="SahneyBentonFalconLang 2010RainforestCollapse"/>

There are also abrupt climate changes associated with the catastrophic draining of glacial lakes. One example of this is the ], which is associated with the draining of ].<ref>{{Cite journal| last5=Taylor | first1=R. B.| last2=Mayewski | author1-link=Richard B. Alley| last6=Clark | first2=P. A.| last4=Stuiver| last3=Sowers| first3=T.| last1=Alley| first4=M.| first5=K. C.| first6=P. U. | title = Holocene climatic instability: A prominent, widespread event 8200 yr ago | journal = Geology | volume = 25| issue = 6 | page = 483 | year = 1997 | doi = 10.1130/0091-7613(1997)025<0483:HCIAPW>2.3.CO;2|bibcode = 1997Geo....25..483A }}</ref> Another example is the ], c. 14,500 years before present (]), which is believed to have been caused by a meltwater pulse probably from either the ]<ref>{{Cite journal | author = Weber | author2 = Clark | author3 = Kuhn | author4 = Timmermann |author-link4= Axel Timmermann | title = Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation | journal = Nature | volume = 510 | issue = 7503 | pages = 134–138 | date = 5 June 2014 | doi = 10.1038/nature13397 |bibcode = 2014Natur.510..134W | pmid=24870232| s2cid = 205238911 }}</ref> or the ].<ref>{{Cite journal | last = Gregoire | first = Lauren | title = Deglacial rapid sea level rises caused by ice-sheet saddle collapses | journal = Nature | volume = 487 | issue = 7406 | pages = 219–222 | date = 11 July 2012 | doi = 10.1038/nature11257 | bibcode = 2012Natur.487..219G | pmid=22785319| s2cid = 4403135 | url = http://eprints.whiterose.ac.uk/76493/8/gregoirel1.pdf }}</ref> These rapid meltwater release events have been hypothesized as a cause for Dansgaard-Oeschger cycles,<ref>{{cite book |author=Bond, G.C. |author2=Showers, W. |author3=Elliot, M. |author4=Evans, M. |author5=Lotti, R. |author6=Hajdas, I. |author7=Bonani, G. |author8=Johnson, S. |year=1999 |chapter=The North Atlantic's 1–2 kyr climate rhythm: relation to Heinrich events, Dansgaard/Oeschger cycles and the little ice age |editor=Clark, P.U. |editor2=Webb, R.S. |editor3=Keigwin, L.D. |title=Mechanisms of Global Change at Millennial Time Scales |series=Geophysical Monograph |publisher=American Geophysical Union, Washington DC |pages=59–76 |isbn=0-87590-033-X |chapter-url=http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al%201999%20%20N.%20Atlantic%201-2.PDF |issue=112 |url-status=dead |archive-url=https://web.archive.org/web/20081029174737/http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al%201999%20%20N.%20Atlantic%201-2.PDF |archive-date=29 October 2008 }}</ref>


In the past, abrupt climate change has likely caused wide-ranging and severe impacts as follows:
A 2017 study concluded that similar conditions to today's ] (atmospheric circulation and hydroclimate changes), ~17,700 years ago, when stratospheric ozone depletion contributed to abrupt accelerated Southern Hemisphere ]. The event coincidentally happened with an estimated 192-year series of massive volcanic eruptions, attributed to ] in ].<ref>{{cite journal|year=2017|publisher=PNAS|title=Synchronous volcanic eruptions and abrupt climate change ~17.7 ka plausibly linked by stratospheric ozone depletion|journal=Proceedings of the National Academy of Sciences|volume=114|issue=38|pages=10035–10040|author=McConnell |display-authors=et al|doi=10.1073/pnas.1705595114|pmid=28874529|pmc=5617275|bibcode=2017PNAS..11410035M|doi-access=free}}</ref>
* ], most notably the ] (often referred colloquially to as the Great Dying) and the ], have been suggested as a consequence of abrupt climate change.<ref name="SahneyBentonFalconLang 2010RainforestCollapse" /><ref name="SahneyBenton2008RecoveryFromProfoundExtinction" /><ref name="crowley" />
{{clear}}
* ]: without interference from abrupt climate change and other extinction events, the biodiversity of Earth would continue to grow.<ref name="SahneyBentonFerry2010LinksDiversityVertebrates">{{cite journal |author=Sahney, S. |author2=Benton, M.J. |author3=Ferry, P.A. |year=2010 |title=Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land |journal=Biology Letters |volume=6 |issue=4 |pages=544–547 |doi=10.1098/rsbl.2009.1024 |pmc=2936204 |pmid=20106856}}</ref>
* Changes in ] such as:
:* Increasing frequency of ] events<ref>{{Cite journal |last1=Trenberth |first1=K. E. |author1-link=Kevin E. Trenberth |last2=Hoar |first2=T. J. |year=1997 |title=El Niño and climate change |journal=] |volume=24 |issue=23 |pages=3057–3060 |bibcode=1997GeoRL..24.3057T |doi=10.1029/97GL03092 |doi-access=free}}</ref><ref>{{Cite journal |last1=Meehl |first1=G. A. |last2=Washington |first2=W. M. |year=1996 |title=El Niño-like climate change in a model with increased atmospheric CO2 concentrations |url=https://zenodo.org/record/1233184 |journal=] |volume=382 |issue=6586 |pages=56–60 |bibcode=1996Natur.382...56M |doi=10.1038/382056a0 |s2cid=4234225}}</ref>
:* Potential disruption to the ], such as that which may have occurred during the ] event.<ref>{{Cite journal |last1=Broecker |first1=W. S. |author-link=Wallace Smith Broecker |year=1997 |title=Thermohaline Circulation, the Achilles Heel of Our Climate System: Will Man-Made CO<sub>2</sub> Upset the Current Balance? |url=http://www.ldeo.columbia.edu/res/pi/arch/docs/broecker_1997.pdf |url-status=dead |journal=] |volume=278 |issue=5343 |pages=1582–1588 |bibcode=1997Sci...278.1582B |doi=10.1126/science.278.5343.1582 |pmid=9374450 |archive-url=https://web.archive.org/web/20091122154415/http://www.ldeo.columbia.edu/res/pi/arch/docs/broecker_1997.pdf |archive-date=22 November 2009}}</ref><ref name="cite doi|10.1038/378165a0" />
:* Changes to the ]<ref>{{Cite journal |last1=Beniston |first1=M. |last2=Jungo |first2=P. |year=2002 |title=Shifts in the distributions of pressure, temperature and moisture and changes in the typical weather patterns in the Alpine region in response to the behavior of the North Atlantic Oscillation |url=http://doc.rero.ch/lm.php?url=1000,43,2,20050718135259-QT/1_bensiton_sdp.pdf |journal=Theoretical and Applied Climatology |volume=71 |issue=1–2 |pages=29–42 |bibcode=2002ThApC..71...29B |doi=10.1007/s704-002-8206-7 |s2cid=14659582}}</ref>
:* Changes in ] (AMOC) which could contribute to more severe weather events.<ref>{{cite journal |author1=J. Hansen |author2=M. Sato |author3=P. Hearty |author4=R. Ruedy |author5=M. Kelley |author6=V. Masson-Delmotte |author7=G. Russell |author8=G. Tselioudis |author9=J. Cao |author10=E. Rignot |author11=I. Velicogna |author12=E. Kandiano |author13=K. von Schuckmann |author14=P. Kharecha |author15=A. N. Legrande |display-authors=4 |year=2015 |title=Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2&nbsp;°C global warming is highly dangerous |url=http://www.atmos-chem-phys-discuss.net/acp-2015-432/ |journal=Atmospheric Chemistry and Physics Discussions |volume=15 |issue=14 |pages=20059–20179 |bibcode=2015ACPD...1520059H |doi=10.5194/acpd-15-20059-2015 |quote=Our results at least imply that strong cooling in the North Atlantic from AMOC shutdown does create higher wind speed. * * * The increment in seasonal mean wind speed of the northeasterlies relative to preindustrial conditions is as much as 10–20%. Such a percentage increase of wind speed in a storm translates into an increase of storm power dissipation by a factor ~1.4–2, because wind power dissipation is proportional to the cube of wind speed. However, our simulated changes refer to seasonal mean winds averaged over large grid-boxes, not individual storms.* * * Many of the most memorable and devastating storms in eastern North America and western Europe, popularly known as superstorms, have been winter cyclonic storms, though sometimes occurring in late fall or early spring, that generate near-hurricane-force winds and often large amounts of snowfall. Continued warming of low latitude oceans in coming decades will provide more water vapor to strengthen such storms. If this tropical warming is combined with a cooler North Atlantic Ocean from AMOC slowdown and an increase in midlatitude eddy energy, we can anticipate more severe baroclinic storms. |doi-access=free |author16=M. Bauer |author17=K.-W. Lo}}</ref>


== See also == == See also ==
{{portal|Climate change|Ecology|Environment}} {{portal|Climate change|Ecology|Environment}}
*]
*]
*] *]
*] *]
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== References == == References ==
{{Reflist|colwidth=30em}} {{Reflist|colwidth=30em}}

== Further reading ==
*{{cite book |author=Alley, Richard B. |author-link=Richard B. Alley |title=The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future |publisher=Princeton University Press |location=Princeton, N.J |year=2000 |isbn=0-691-00493-5 |url=https://archive.org/details/twomiletimemachi00alle }}
*{{cite book |author=Calvin, William H. |title=A Brain for All Seasons: Human Evolution and Abrupt Climate Change |publisher=University of Chicago Press |location=London and Chicago |year=2002 |isbn=0-226-09201-1 |url=https://archive.org/details/brainforallseaso00calv }}
*{{cite book | last = Calvin | first = William H. | title = Global fever: How to treat climate change| publisher=University of Chicago Press | year = 2008 |location=Chicago and London| url = http://www.williamcalvin.org/bk14}}
*{{cite book |author=Cox, John |title=Climate Crash: Abrupt Climate Change and What It Means for Our Future |publisher=Joseph Henry Press |location=Washington, D.C |year=2005 |isbn=0-309-09312-0 |url=https://archive.org/details/climatecrashabru00coxj }}
*{{cite web
|year=2008
|title=Abrupt Climate Change. A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research
|publisher=]
|location=Reston, VA
|author1=Clark, P.U. |author2=A.J. Weaver |author3=E. Brook |author4=E.R. Cook |author5=T.L. Delworth |author6=K. Steffen |url=http://www.climatescience.gov/Library/sap/sap3-4/final-report/default.htm#finalreport
|archive-url=https://web.archive.org/web/20090812234931/http://climatescience.gov/Library/sap/sap3-4/final-report/default.htm
|archive-date=12 August 2009
|url-status=dead
}}
*{{cite journal |last1=Drummond |first1=Carl N. |last2=Wilkinson |first2=Bruce H. |title=Interannual Variability in Climate Data |journal=Journal of Geology |volume=114 |pages=325–39 |year=2006 |doi=10.1086/500992 |bibcode=2006JG....114..325D |issue=3|s2cid=128885809 }}
*{{cite book |author1=Parson, Edward |author-link2=Andrew Dessler |author2=Dessler, Andrew Emory |title=The Science and Politics of Global Climate Change: A Guide to the Debate |publisher=Cambridge University Press |location=Cambridge, UK |year=2006 |isbn=0-521-53941-2 |url=https://archive.org/details/sciencepoliticso0000dess |url-access=registration }}
*{{cite book |author1=National Research Council |author-link=National Research Council (United States) |title=Abrupt Impacts of Climate Change |date=2013 |url=http://www.nap.edu/read/18373/|doi=10.17226/18373 |isbn=978-0-309-28773-9 }}
*{{cite web|last1=Schwartz |first1=Peter |last2=Randall |first2=Doug |title=An Abrupt Climate Change Scenario and Its Implications for United States National Security |date=October 2003 |url=http://www.climate.org/PDF/clim_change_scenario.pdf |url-status=dead |archive-url=https://web.archive.org/web/20090320054750/http://www.climate.org/PDF/clim_change_scenario.pdf |archive-date=20 March 2009 }}
*{{cite web |last1=Weart |first1=Spencer |title=Rapid Climate Change |url=https://history.aip.org/climate/rapid.htm |website=The Discovery of Global Warming |publisher=American Institute of Physics |access-date=9 January 2020}} (historical survey)


{{Global warming}} {{Global warming}}

Latest revision as of 10:14, 22 December 2024

Form of climate change

Clathrate hydrates have been identified as a possible agent for abrupt changes.

An abrupt climate change occurs when the climate system is forced to transition at a rate that is determined by the climate system energy-balance. The transition rate is more rapid than the rate of change of the external forcing, though it may include sudden forcing events such as meteorite impacts. Abrupt climate change therefore is a variation beyond the variability of a climate. Past events include the end of the Carboniferous Rainforest Collapse, Younger Dryas, Dansgaard–Oeschger events, Heinrich events and possibly also the Paleocene–Eocene Thermal Maximum. The term is also used within the context of climate change to describe sudden climate change that is detectable over the time-scale of a human lifetime. Such a sudden climate change can be the result of feedback loops within the climate system or tipping points in the climate system.

Scientists may use different timescales when speaking of abrupt events. For example, the duration of the onset of the Paleocene–Eocene Thermal Maximum may have been anywhere between a few decades and several thousand years. In comparison, climate models predict that under ongoing greenhouse gas emissions, the Earth's near surface temperature could depart from the usual range of variability in the last 150 years as early as 2047.

Definitions

Abrupt climate change can be defined in terms of physics or in terms of impacts: "In terms of physics, it is a transition of the climate system into a different mode on a time scale that is faster than the responsible forcing. In terms of impacts, an abrupt change is one that takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it. These definitions are complementary: the former gives some insight into how abrupt climate change comes about; the latter explains why there is so much research devoted to it."

Timescales

Timescales of events described as abrupt may vary dramatically. Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming of +10 °C (+18 °F) within a timescale of a few years. Other abrupt changes are the +4 °C (+7.2 °F) on Greenland 11,270 years ago or the abrupt +6 °C (11 °F) warming 22,000 years ago on Antarctica.

By contrast, the Paleocene–Eocene Thermal Maximum may have initiated anywhere between a few decades and several thousand years. Finally, Earth System's models project that under ongoing greenhouse gas emissions as early as 2047, the Earth's near surface temperature could depart from the range of variability in the last 150 years.

Past events

The Younger Dryas period of abrupt climate change is named after the alpine flower, Dryas.

Several periods of abrupt climate change have been identified in the paleoclimatic record. Notable examples include:

  • About 25 climate shifts, called Dansgaard–Oeschger cycles, which have been identified in the ice core record during the glacial period over the past 100,000 years.
  • The Younger Dryas event, notably its sudden end. It is the most recent of the Dansgaard–Oeschger cycles and began 12,900 years ago and moved back into a warm-and-wet climate regime about 11,600 years ago. It has been suggested that "the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system." A model for this event based on disruption to the thermohaline circulation has been supported by other studies.
  • The Paleocene–Eocene Thermal Maximum, timed at 55 million years ago, which may have been caused by the release of methane clathrates, although potential alternative mechanisms have been identified. This was associated with rapid ocean acidification
  • The Permian–Triassic Extinction Event, in which up to 95% of all species became extinct, has been hypothesized to be related to a rapid change in global climate. Life on land took 30 million years to recover.
  • The Carboniferous Rainforest Collapse occurred 300 million years ago, at which time tropical rainforests were devastated by climate change. The cooler, drier climate had a severe effect on the biodiversity of amphibians, the primary form of vertebrate life on land.

There are also abrupt climate changes associated with the catastrophic draining of glacial lakes. One example of this is the 8.2-kiloyear event, which is associated with the draining of Glacial Lake Agassiz. Another example is the Antarctic Cold Reversal, c. 14,500 years before present (BP), which is believed to have been caused by a meltwater pulse probably from either the Antarctic ice sheet or the Laurentide Ice Sheet. These rapid meltwater release events have been hypothesized as a cause for Dansgaard–Oeschger cycles.

A five-year study led by the Oxford School of Archaeology and additionally conducted by Royal Holloway, University of London, the Oxford University Museum of Natural History, and the National Oceanography Centre Southampton completed in 2013 called "Response of Humans to Abrupt Environmental Transitions" and referred to as "RESET" aimed to see if the hypothesis that humans have major development shifts during or immediately after abrupt climate changes with the aid of knowledge pulled from research on the palaeoenvironmental conditions, prehistoric archaeological history, oceanography, and volcanic geology of the last 130,000 years and across continents. It also aimed to predict possible human behavior in the event of climate change, and the timing of climate change.

A 2017 study concluded that similar conditions to today's Antarctic ozone hole (atmospheric circulation and hydroclimate changes), ~17,700 years ago, when stratospheric ozone depletion contributed to abrupt accelerated Southern Hemisphere deglaciation. The event coincidentally happened with an estimated 192-year series of massive volcanic eruptions, attributed to Mount Takahe in West Antarctica.

Possible precursors

Most abrupt climate shifts are likely due to sudden circulation shifts, analogous to a flood cutting a new river channel. The best-known examples are the several dozen shutdowns of the North Atlantic Ocean's Meridional Overturning Circulation during the last ice age, affecting climate worldwide.

  • The current warming of the Arctic, the duration of the summer season, is considered abrupt and massive.
  • Antarctic ozone depletion caused significant atmospheric circulation changes.
  • There have also been two occasions when the Atlantic's Meridional Overturning Circulation lost a crucial safety factor. The Greenland Sea flushing at 75 °N shut down in 1978, recovering over the next decade. Then the second-largest flushing site, the Labrador Sea, shut down in 1997 for ten years. While shutdowns overlapping in time have not been seen during the 50 years of observation, previous total shutdowns had severe worldwide climate consequences.

It has been postulated that teleconnections – oceanic and atmospheric processes on different timescales – connect both hemispheres during abrupt climate change.

Climate feedback effects

The dark ocean surface reflects only 6 percent of incoming solar radiation; sea ice reflects 50 to 70 percent.
See also: Climate change feedback and Tipping points in the climate system

One source of abrupt climate change effects is a feedback process, in which a warming event causes a change that adds to further warming. The same can apply to cooling. Examples of such feedback processes are:

The probability of abrupt change for some climate related feedbacks may be low. Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly and warming that is sustained over longer time periods.

Tipping points in the climate system

Possible tipping elements in the climate system include regional effects of climate change, some of which had abrupt onset and may therefore be regarded as abrupt climate change. Scientists have stated, "Our synthesis of present knowledge suggests that a variety of tipping elements could reach their critical point within this century under anthropogenic climate change".

This section is an excerpt from Tipping points in the climate system. In climate science, a tipping point is a critical threshold that, when crossed, leads to large, accelerating and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society and may accelerate global warming. Tipping behavior is found across the climate system, for example in ice sheets, mountain glaciers, circulation patterns in the ocean, in ecosystems, and the atmosphere. Examples of tipping points include thawing permafrost, which will release methane, a powerful greenhouse gas, or melting ice sheets and glaciers reducing Earth's albedo, which would warm the planet faster. Thawing permafrost is a threat multiplier because it holds roughly twice as much carbon as the amount currently circulating in the atmosphere.

Volcanism

Isostatic rebound in response to glacier retreat (unloading) and increased local salinity have been attributed to increased volcanic activity at the onset of the abrupt Bølling–Allerød warming. They are associated with the interval of intense volcanic activity, hinting at an interaction between climate and volcanism: enhanced short-term melting of glaciers, possibly via albedo changes from particle fallout on glacier surfaces.

Impacts

A summary of the path of the thermohaline circulation. Blue paths represent deep-water currents, and red paths represent surface currents.
The Permian–Triassic extinction event, labelled "P–Tr" here, is the most significant extinction event in this plot for marine genera.

In the past, abrupt climate change has likely caused wide-ranging and severe impacts as follows:

See also

References

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