abrupt climate change

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."{{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}}

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.{{cite journal |last1=Grachev |first1=A.M. |last2=Severinghaus |first2=J.P. |year=2005 |title=A revised +10±4 °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}} Other abrupt changes are the +{{convert|4|C-change||disp=x| (+|)}} on Greenland 11,270 years ago{{cite journal |last1=Kobashi |first1=T. |last2=Severinghaus |first2=J.P. |last3=Barnola |first3=J. |date=30 April 2008 |title=4 ± 1.5 °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}} or the abrupt +{{convert|6|C-change}} warming 22,000 years ago on Antarctica.{{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}}

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.

Image:Dryas drummondii6.jpg 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.{{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}}
• 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.{{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."{{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=Nature |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}} A model for this event based on disruption to the thermohaline circulation has been supported by other studies.{{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=Nature |volume=378 |issue=6553 |page=165 |bibcode=1995Natur.378..165M |doi=10.1038/378165a0 |s2cid=4302999}}
• The Paleocene–Eocene Thermal Maximum, timed at 55 million years ago, which may have been caused by the release of methane clathrates,{{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}} although potential alternative mechanisms have been identified.{{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}} This was associated with rapid ocean acidification{{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=Science |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}}
• 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.{{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}}{{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=Science |volume=240 |issue=4855 |pages=996–1002 |bibcode=1988Sci...240..996C |doi=10.1126/science.240.4855.996 |pmid=17731712 |s2cid=44921662}} Life on land took 30 million years to recover.{{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}}
• 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.{{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}} 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{{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}} or the Laurentide Ice Sheet.{{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}} These rapid meltwater release events have been hypothesized as a cause for Dansgaard–Oeschger cycles.{{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}}

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{{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}} 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.{{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}}{{cite web |title=RESET |url=https://c14.arch.ox.ac.uk/reset/index.html |publisher=Oxford University}} It also aimed to predict possible human behavior in the event of climate change, and the timing of climate change.{{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}}

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.{{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}}

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.{{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 = Science | 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 }}

• The current warming of the Arctic, the duration of the summer season, is considered abrupt and massive.{{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}}
• 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.{{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 }} Then the second-largest flushing site, the Labrador Sea, shut down in 1997{{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}} for ten years.{{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}} 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.{{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}}

File:NORTH POLE Ice (19626661335).jpg

{{See also|Climate change feedback|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.{{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}} The same can apply to cooling. Examples of such feedback processes are:

• Ice–albedo feedback in which the advance or retreat of ice cover alters the albedo ("whiteness") of the earth and its ability to absorb the sun's energy.{{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 }}
• Soil carbon feedback is the release of carbon from soils in response to global warming.
• The dying and the burning of forests by global warming.{{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 = PNAS| 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}}

The probability of abrupt change for some climate related feedbacks may be low.

{{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}}

{{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}} 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.

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.{{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}} 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".{{excerpt|Tipping points in the climate system|paragraphs=1|file=no}}

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.{{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 }}

Image:Thermohaline Circulation 2.png. Blue paths represent deep-water currents, and red paths represent surface currents.|thumb|right]]

Image:Extinction intensity.svg.|thumb|right]]

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

• Mass extinctions, most notably the Permian–Triassic extinction event (often referred colloquially to as the Great Dying) and the Carboniferous Rainforest Collapse, have been suggested as a consequence of abrupt climate change.
• Loss of biodiversity: without interference from abrupt climate change and other extinction events, the biodiversity of Earth would continue to grow.{{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}}
• Changes in ocean circulation such as:

:* Increasing frequency of El Niño events{{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=Geophysical Research Letters |volume=24 |issue=23 |pages=3057–3060 |bibcode=1997GeoRL..24.3057T |doi=10.1029/97GL03092 |doi-access=free}}{{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=Nature |volume=382 |issue=6586 |pages=56–60 |bibcode=1996Natur.382...56M |doi=10.1038/382056a0 |s2cid=4234225}}

:* Potential disruption to the thermohaline circulation, such as that which may have occurred during the Younger Dryas event.{{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 CO₂ Upset the Current Balance? |url=http://www.ldeo.columbia.edu/res/pi/arch/docs/broecker_1997.pdf |url-status=dead |journal=Science |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}}

:* Changes to the North Atlantic oscillation{{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}}

:* Changes in Atlantic meridional overturning circulation (AMOC) which could contribute to more severe weather events.{{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 °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}}

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