Editing Younger Dryas (section)

== Climate ==
[[File:Evolution of temperature in the Post-Glacial period according to Greenland ice cores (Younger Dryas).jpg|thumb|upright=1.25|[[Greenland ice cores]] since the [[Last Glacial Maximum]] show very low temperatures for the most part of the Younger Dryas, which then rise rapidly during the [[Holocene]] transition<ref>{{cite journal |last1=Zalloua |first1=Pierre A. |last2=Matisoo-Smith|first2=Elizabeth |title=Mapping Post-Glacial expansions: The Peopling of Southwest Asia |journal=[[Scientific Reports]] |date=2017 |volume=7 |page=40338 |doi=10.1038/srep40338 |pmid=28059138 |issn=2045-2322 |bibcode=2017NatSR...740338P |pmc=5216412}}</ref>]]
[[File:Younger Dryas and Holocene temperature changes.png|thumb|upright=1.25|Temperature changes, determined as [[Proxy (climate)|proxy temperatures]], taken from the central region of Greenland's ice sheet during the Late Pleistocene and beginning of the Holocene.]]
[[File:20191021 Temperature from 20,000 to 10,000 years ago - recovery from ice age.png |thumb |upright=1.25 |Temperatures in Antarctica, derived from EPICA Dome&nbsp;C Ice Core]]
As with the other geologic periods, [[paleoclimate]] during the Younger Dryas is reconstructed through [[proxy (climate)|proxy]] data such as traces of [[pollen]], [[ice core]]s and layers of marine and lake [[sediment]]s.<ref name="Yu1998">{{cite journal |last1=Yu |first1=Zicheng |last2=Eicher |first2=Ulrich |date=1998 |title=Abrupt climate oscillations during the last deglaciation in central North America |journal=[[Science (journal)|Science]] |volume=282 |issue=5397 |pages=2235–2238 |bibcode=1998Sci...282.2235Y |jstor=2897126 |doi=10.1126/science.282.5397.2235 |doi-access=free |pmid=9856941}}</ref> Collectively, this evidence shows that significant cooling across the Northern Hemisphere began around 12,870 ± 30 years BP.<ref name="Cheng2020">{{Cite journal |last1=Cheng |first1=Hai |last2=Zhang |first2=Haiwei |last3=Spötl |first3=Christoph |last4=Baker |first4=Jonathan |last5=Sinha |first5=Ashish |last6=Li |first6=Hanying |last7=Bartolomé |first7=Miguel |last8=Moreno |first8=Ana |last9=Kathayat |first9=Gayatri |last10=Zhao |first10=Jingyao |last11=Dong |first11=Xiyu |last12=Li |first12=Youwei |last13=Ning |first13=Youfeng |last14=Jia |first14=Xue |last15=Zong |first15=Baoyun |date=22 September 2020 |title=Timing and structure of the Younger Dryas event and its underlying climate dynamics |journal=Proceedings of the National Academy of Sciences |volume=117 |issue=38 |pages=23408–23417 |doi=10.1073/pnas.2007869117 |issn=0027-8424 |pmc=7519346 |pmid=32900942 |doi-access=free |bibcode=2020PNAS..11723408C }}</ref> It was particularly severe in [[Greenland]], where temperatures declined by {{convert|4-10|C-change|F-change}},<ref name="Buizert2014">{{Cite journal |last1=Buizert |first1=C. |last2=Gkinis |first2=V. |last3=Severinghaus |first3=J.P. |last4=He |first4=F. |last5=Lecavalier |first5=B.S. |last6=Kindler |first6=P. |last7=Leuenberger |first7=M. |last8=Carlson |first8=A. E. |last9=Vinther |first9=B. |last10=Masson-Delmotte |first10=V. |last11=White |first11=J. W. C. |display-authors=6 |date=5 September 2014 |title=Greenland temperature response to climate forcing during the last deglaciation |journal=[[Science (journal)|Science]] |language=en |volume=345 |issue=6201 |pages=1177–1180 |bibcode=2014Sci...345.1177B |doi=10.1126/science.1254961 |issn=0036-8075 |pmid=25190795 |s2cid=206558186 |url=https://escholarship.org/uc/item/6n89h7c3 }}</ref> in an abrupt fashion.<ref name="Alley2000" /> Temperatures at the Greenland summit were up to {{convert|15|C-change}} colder than at the start of the 21st century.<ref name="Alley2000">{{Cite journal |last=Alley |first=Richard B. |year=2000 |title=The Younger Dryas cold interval as viewed from central Greenland |journal=[[Quaternary Science Reviews]] |volume=19 |issue=1 |pages=213–226 |bibcode=2000QSRv...19..213A |doi=10.1016/S0277-3791(99)00062-1}}</ref><ref name="Severinghaus1998">{{cite journal |last1=Severinghaus |first1=Jeffrey P. |last2=Sowers |first2=Todd |last3=Brook |first3=Edward J. |last4=Alley |first4=Richard B. |last5=Bender |first5=Michael L. |display-authors=1 |year=1998 |title=Timing of abrupt climate change at the end of the Younger Dryas interval from thermally fractionated gases in polar ice |journal=[[Nature (journal)|Nature]] |volume=391 |issue=6663 |pages=141–146 |bibcode=1998Natur.391..141S |doi=10.1038/34346 |s2cid=4426618}}</ref> 

Strong cooling of around {{convert|2-6|C-change|F-change|0}} had also taken place in Europe.<ref name="Carlson2013" /> Icefields and [[glacier]]s formed in upland areas of [[Great Britain]], while many lowland areas developed [[permafrost]],<ref name="Sissons1979">{{cite journal |last=Sissons |first=J.B. |year=1979 |title=The Loch Lomond stadial in the British Isles |journal=[[Nature (journal)|Nature]] |volume=280 |issue=5719 |pages=199–203 |bibcode=1979Natur.280..199S |doi=10.1038/280199a0 |s2cid=4342230}}</ref> implying a cooling of {{convert|-5|C|F}} and a mean annual temperature no higher than {{convert|-1|C}}.<ref name="Severinghaus1998" /><ref>{{Cite journal |last1=Atkinson |first1=T.C. |last2=Briffa |first2=K.R. |last3=Coope |first3=G.R. |year=1987 |title=Seasonal temperatures in Britain during the past 22,000 years, reconstructed using beetle remains |journal=[[Nature (journal)|Nature]] |volume=325 |issue=6105 |pages=587–592 |bibcode=1987Natur.325..587A |doi=10.1038/325587a0 |s2cid=4306228}}</ref> [[North America]] also became colder, particularly in the eastern and central areas.<ref name="Yu1998" /> While the [[Pacific Northwest]] region cooled by {{convert|2-3|C-change|F-change}}, cooling in western North America was generally less intense.<ref>{{cite journal |last1=Barron |first1=John A. |last2=Heusser |first2=Linda |last3=Herbert |first3=Timothy |last4=Lyle |first4=Mitch |date=2003-03-01 |title=High-resolution climatic evolution of coastal northern California during the past 16,000&nbsp;years |journal=[[Paleoceanography and Paleoclimatology]] |volume=18 |issue=1 |pages=1020 |doi=10.1029/2002pa000768 |doi-access=free |issn=1944-9186 |bibcode=2003PalOc..18.1020B}}</ref><ref>{{Cite journal |last1=Kienast |first1=Stephanie S. |last2=McKay |first2=Jennifer L. |date=2001-04-15 |title=Sea surface temperatures in the subarctic northeast Pacific reflect millennial-scale climate oscillations during the last 16&nbsp;kyrs |journal= [[Geophysical Research Letters]] |volume=28 |issue=8 |pages=1563–1566 |doi=10.1029/2000gl012543 |doi-access=free |issn=1944-8007 |bibcode=2001GeoRL..28.1563K}}</ref><ref>{{Cite journal |last=Mathewes |first=Rolf W. |date=1993-01-01 |title=Evidence for Younger Dryas-age cooling on the North Pacific coast of America |journal=[[Quaternary Science Reviews]] |volume=12 |issue=5 |pages=321–331 |doi=10.1016/0277-3791(93)90040-s |bibcode=1993QSRv...12..321M}}</ref><ref>{{cite journal |last1=Chase |first1=Marianne |last2=Bleskie |first2=Christina |last3=Walker |first3=Ian R. |last4=Gavin |first4=Daniel G. |last5=Hu |first5=Feng Sheng |date=January 2008 |title=Midge-inferred Holocene summer temperatures in southeastern British Columbia, Canada |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |language=en |volume=257 |issue=1–2 |pages=244–259 |doi=10.1016/j.palaeo.2007.10.020 |bibcode=2008PPP...257..244C}}</ref><ref>{{Cite journal |last1=Denniston |first1=R.F. |last2=Gonzalez|first2=L.A. |last3=Asmerom |first3=Y. |last4=Polyak |first4=V. |last5=Reagan |first5=M.K. |last6=Saltzman |first6=M.R. |date=25 December 2001 |title=A high-resolution speleothem record of climatic variability at the Allerød–Younger Dryas transition in Missouri, central United States|journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=176 |issue=1–4 |pages=147–155 |doi=10.1016/S0031-0182(01)00334-0 |bibcode=2001PPP...176..147D |citeseerx=10.1.1.556.3998}}</ref><ref name="Elias2013">{{Cite book |author1=Elias, Scott A. |author2=Mock, Cary J. |year=2013 |title=Encyclopedia of Quaternary Science |publisher=Elsevier |isbn=978-0-444-53642-6 |pages=126–127 |oclc=846470730}}</ref> While the [[Orca Basin]] in the [[Gulf of Mexico]] still experienced a drop in [[sea surface temperature]] of  2.4 ± 0.6°C,<ref>{{cite journal |last1=Williams |first1=Carlie |last2=Flower |first2=Benjamin P. |last3=Hastings |first3=David W. |last4=Guilderson |first4=Thomas P. |last5=Quinn |first5=Kelly A. |last6=Goddard |first6=Ethan A. |date=7 December 2010 |title=Deglacial abrupt climate change in the Atlantic Warm Pool: A Gulf of Mexico perspective |journal=[[Paleoceanography and Paleoclimatology]] |volume=25 |issue=4 |pages=1–12 |doi=10.1029/2010PA001928 |bibcode=2010PalOc..25.4221W |s2cid=58890724 }}</ref> land areas closer to it, such as [[Texas]], the [[Grand Canyon]] area<ref>{{cite journal |last1=Cole |first1=Kenneth L. |last2=Arundel |first2=Samantha T. |year=2005 |title=Carbon isotopes from fossil packrat pellets and elevational movements of Utah agave plants reveal the Younger Dryas cold period in Grand Canyon, Arizona |journal=[[Geology (journal)|Geology]] |volume=33 |issue=9 |page=713 |doi=10.1130/g21769.1 |bibcode=2005Geo....33..713C |s2cid=55309102 }}</ref> and [[New Mexico]], ultimately did not cool as much as the continental interior.<ref name="Meltzer2010">{{cite journal |last1=Meltzer |first1=David J. |last2=Holliday |first2=Vance T. |date=2010-03-01 |title=Would North American Paleoindians have noticed Younger Dryas age climate changes? |journal=[[Journal of World Prehistory]] |volume=23 |issue=1 |pages=1–41 |doi=10.1007/s10963-009-9032-4 |s2cid=3086333 |issn=0892-7537}}</ref><ref>{{cite journal |last1=Nordt |first1=Lee C. |last2=Boutton |first2=Thomas W. |last3=Jacob |first3=John S. |last4=Mandel |first4=Rolfe D. |date=2002-09-01 |title=C4 Plant productivity and climate – {{CO2}} variations in south-central Texas during the late Quaternary |journal=[[Quaternary Research]] |volume=58 |issue=2 |pages=182–188 |doi=10.1006/qres.2002.2344 |bibcode=2002QuRes..58..182N |s2cid=129027867}}</ref><ref>{{Cite journal |last1=Feng |first1=Weimin |last2=Hardt |first2=Benjamin F. |last3=Banner |first3=Jay L. |last4=Meyer |first4=Kevin J. |last5=James |first5=Eric W. |last6=Musgrove |first6=MaryLynn |last7=Edwards |first7=R. Lawrence |last8=Cheng |first8=Hai |last9=Min |first9=Angela |date=2014-09-01 |title=Changing amounts and sources of moisture in the U.S. southwest since the Last Glacial Maximum in response to global climate change |journal=[[Earth and Planetary Science Letters]] |volume=401 |pages=47–56 |doi=10.1016/j.epsl.2014.05.046 |bibcode=2014E&PSL.401...47F}}</ref> The [[Southeastern United States]] became warmer and wetter than before.<ref name="Griggs2017" /><ref name="Meltzer2010" /><ref name="Elias2013" /> There was warming in and around the [[Caribbean Sea]], and in [[West Africa]].<ref name="Carlson2013" />

It was once believed that the Younger Dryas cooling started at around the same time across the Northern Hemisphere.<ref>{{Cite journal |last1=Benson |first1=Larry |last2=Burdett |first2=James |last3=Lund |first3=Steve |last4=Kashgarian |first4=Michaele |last5=Mensing |first5=Scott |date=17 July 1997 |title=Nearly synchronous climate change in the Northern Hemisphere during the last glacial termination |journal=[[Nature (journal)|Nature]] |language=en |volume=388 |issue=6639 |pages=263–265 |doi=10.1038/40838 |issn=1476-4687}}</ref> However, [[varve]] (sedimentary rock) analysis carried out in 2015 suggested that the cooling proceeded in two stages: first along latitude 56–54°N, 12,900–13,100&nbsp;years ago, and then further north, 12,600–12,750&nbsp;years ago.<ref>{{cite journal |author1=Muschitiello, F. |author2=Wohlfarth, B. |year=2015 |title=Time-transgressive environmental shifts across Northern Europe at the onset of the Younger Dryas |journal=[[Quaternary Science Reviews]] |volume=109 |pages=49–56|doi=10.1016/j.quascirev.2014.11.015 }}</ref> Evidence from [[Lake Suigetsu]] cores in [[Japan]] and the [[Puerto Princesa Subterranean River National Park|Puerto Princesa cave complex]] in the [[Philippines]] shows that the onset of the Younger Dryas in East Asia was delayed by several hundred years relative to the North Atlantic.<ref name="Nakagawa2003">{{cite journal | last1 = Nakagawa | first1 = T | last2 = Kitagawa | first2 = H. | last3 = Yasuda | first3 = Y. | last4 = Tarasov | first4 = P.E. | last5 = Nishida | first5 = K. | last6 = Gotanda | first6 = K. | last7 = Sawai | first7 = Y. |collaboration = Yangtze River Civilization Program Members | year = 2003 | title = Asynchronous climate changes in the North Atlantic and Japan during the last termination | journal = [[Science (journal)|Science]] | volume = 299 | issue = 5607| pages = 688–691 | doi=10.1126/science.1078235| pmid = 12560547 | bibcode = 2003Sci...299..688N | s2cid = 350762 }}</ref><ref name="Partin2015" /> Further, the cooling was uniform throughout the year, but had a distinct seasonal pattern. In most places in the Northern Hemisphere, winters became much colder than before, but springs cooled by less, while there was either no temperature change or even slight warming during the summer.<ref name="Buizert2014" /><ref name="Schenk2018" /> An exception appears to have taken place in what is now [[Maine]], where winter temperatures remained stable, yet summer temperatures decreased by up to {{convert|7.5|C-change}}.<ref name="Dieffenbacher-Krall2016">{{Cite journal |last1=Dieffenbacher-Krall |first1=Ann C. |last2=Borns |first2=Harold W. |last3=Nurse |first3=Andrea M. |last4=Langley |first4=Geneva E.C. |last5=Birkel |first5=Sean |last6=Cwynar |first6=Les C. |last7=Doner |first7=Lisa A. |last8=Dorion |first8=Christopher C. |last9=Fastook |first9=James |date=2016-03-01 |title=Younger Dryas paleoenvironments and ice dynamics in northern Maine: A multi-proxy, case history |journal=Northeastern Naturalist |volume=23 |issue=1 |pages=67–87 |doi=10.1656/045.023.0105 |s2cid=87182583|issn=1092-6194}}</ref> 

While the Northern Hemisphere cooled, considerable warming occurred in the Southern Hemisphere.<ref name="Partin2015" /> Sea surface temperatures were warmer by {{convert|0.3-1.9|C-change|F-change|1}}, and [[Antarctica]], [[South America]] (south of [[Venezuela]]) and [[New Zealand]] all experienced warming.<ref name="Carlson2013" /> The net temperature change was a relatively modest<ref>{{Cite journal |last1=Shakun |first1=Jeremy D. |last2=Carlson |first2=Anders E. |date=1 July 2010 |title=A global perspective on Last Glacial Maximum to Holocene climate change |journal=[[Quaternary Science Reviews]] |series=Special Theme: Arctic Palaeoclimate Synthesis (PP. 1674–1790) |volume=29 |issue=15 |pages=1801–1816 |doi=10.1016/j.quascirev.2010.03.016 |bibcode=2010QSRv...29.1801S |issn=0277-3791 }}</ref> cooling of {{convert|0.6|C-change|F-change}}.<ref name="Carlson2013" /> Temperature changes of the Younger Dryas lasted 1,150–1,300&nbsp;years.<ref name="Bjorck2007a" /><ref name="Bjorck1996" /> According to the  [[International Commission on Stratigraphy]], the Younger Dryas ended around 11,700&nbsp;years ago,<ref>{{Cite journal |author1=Walker, Mike |display-authors=etal |date=3 October 2008 |title=Formal definition and dating of the GSSP, etc. |journal=[[Journal of Quaternary Science]] |volume=24 |issue=1 |pages=3–17 |doi=10.1002/jqs.1227 |s2cid=40380068 |bibcode=2009JQS....24....3W |url=http://www.stratigraphy.org/GSSP/Holocene.pdf |access-date=11 November 2019}}</ref> although some research places it closer to 11,550&nbsp;years ago.<ref>{{cite journal |last=Taylor |first=K.C. |year=1997 |title=The Holocene-Younger Dryas transition recorded at Summit, Greenland |journal=[[Science (journal)|Science]] |volume=278 |issue=5339 |pages=825–827 |doi=10.1126/science.278.5339.825 |bibcode=1997Sci...278..825T |url=https://cloudfront.escholarship.org/dist/prd/content/qt9c8680t0/qt9c8680t0.pdf}}</ref><ref>{{cite journal |last=Spurk |first=M. |year=1998 |title=Revisions and extension of the Hohenheim oak and pine chronologies: New evidence about the timing of the Younger Dryas/Preboreal transition |journal=Radiocarbon |volume=40 |issue=3 |pages=1107–1116 |doi=10.1017/S0033822200019159 |bibcode=1998Radcb..40.1107S |doi-access=free }}</ref><ref>{{cite journal |last1=Gulliksen |first1=Steinar |year=1998 |title=A calendar age estimate of the Younger Dryas-Holocene boundary at Krakenes, western Norway |journal=Holocene |volume=8 |issue= 3|pages=249–259 |doi=10.1191/095968398672301347 |last2=Birks |first2=H.H. |last3=Possnert |first3=G. |last4=Mangerud |first4=J. |bibcode=1998Holoc...8..249G |s2cid=129916026 }}</ref><ref>{{Cite journal |last1=Kobashia |first1=Takuro |last2=Severinghaus |first2=Jeffrey P. |last3=Barnola |first3=Jean-Marc |year=2008 |title=4 ± 1.5&nbsp;°C abrupt warming 11,270&nbsp;years ago identified from trapped air in Greenland ice |journal=[[Earth and Planetary Science Letters]] |volume=268 |issue=3–4 |pages=397–407 |doi=10.1016/j.epsl.2008.01.032 |bibcode=2008E&PSL.268..397K}}</ref><ref>{{cite journal |last1=Hughen |first1=K.A. |last2=Southon |first2=J.R. |last3=Lehman |first3=S.J. |last4=Overpeck |first4=J.T. |year=2000 |title=Synchronous radiocarbon and climate shifts during the last deglaciation |journal=[[Science (journal)|Science]] |volume=290 |issue=5498 |pages=1951–1954 |doi=10.1126/science.290.5498.1951 |pmid=11110659 |bibcode = 2000Sci...290.1951H }}</ref> 

The end of Younger Dryas was also abrupt: in previously cooled areas, warming to previous levels took place over 50–60 years.<ref name="Alley1993">{{Cite journal |last1=Alley |first1=Richard B. |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. |display-authors=6 |year=1993 |title=Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event |journal=[[Nature (journal)|Nature]] |volume=362 |issue=6420 |pages=527–529 |bibcode=1993Natur.362..527A |doi=10.1038/362527a0 |s2cid=4325976 |hdl-access=free |hdl=11603/24307}}</ref><ref name="Partin2015" /> The tropics experienced more gradual temperature recovery over several centuries;<ref name="Partin2015" /> the exception was in tropical Atlantic areas such as [[Costa Rica]], where temperature change was similar to Greenland's.<ref>{{Cite journal |last1=Hughen |first1=Konrad A. |last2=Overpeck |first2=Jonathan T. |last3=Peterson |first3=Larry C. |last4=Trumbore |first4=Susan |date=7 March 1996 |title=Rapid climate changes in the tropical Atlantic region during the last deglaciation |journal=[[Nature (journal)|Nature]] |language=en |volume=380 |issue=6569 |pages=51–54 |doi=10.1038/380051a0 |bibcode=1996Natur.380...51H |s2cid=4344716 |issn=0028-0836 |url=https://escholarship.org/uc/item/2d5484b0 }}</ref> The [[Holocene]] warming then proceeded across the globe, following an increase in [[carbon dioxide]] levels during the YD period<ref name="Shakun2012" /> (from ~210 ppm to ~275 ppm<ref>{{Cite journal |last1=Beerling |first1=David J. |last2=Birks |first2=Hilary H. |last3=Woodward |first3=F. Ian |date=December 1995 |title=Rapid late-glacial atmospheric CO 2 changes reconstructed from the stomatal density record of fossil leaves |url=https://onlinelibrary.wiley.com/doi/10.1002/jqs.3390100407 |journal=[[Journal of Quaternary Science]] |language=en |volume=10 |issue=4 |pages=379–384 |doi=10.1002/jqs.3390100407 |bibcode=1995JQS....10..379B |issn=0267-8179 |access-date=19 December 2023 |via=Wiley Online Library}}</ref>). 

=== Ice cover ===
Younger Dryas cooling was often accompanied by [[glacier]] advance and lowering of the regional [[snow line]], with evidence found in areas such as Scandinavia,<ref name="Bjorck2007a">[[Svante Björck|Björck, S.]] (2007) ''Younger Dryas oscillation, global evidence.'' In S. A. Elias, (Ed.): ''Encyclopedia of Quaternary Science,'' Volume 3, pp. 1987–1994. Elsevier B.V., Oxford.</ref> the [[Swiss Alps]]<ref name="Carlson2013" />  and the [[Dinaric Alps]] in the [[Balkans]],<ref>{{Cite journal |last1=Çiner |first1=Attila |last2=Stepišnik |first2=Uroš |last3=Sarıkaya |first3=M. Akif |last4=Žebre |first4=Manja |last5=Yıldırım |first5=Cengiz |date=24 June 2019 |title=Last Glacial Maximum and Younger Dryas piedmont glaciations in Blidinje, the Dinaric Mountains (Bosnia and Herzegovina): insights from 36Cl cosmogenic dating |journal=Mediterranean Geoscience Reviews |language=en |volume=1 |issue=1 |pages=25–43 |doi=10.1007/s42990-019-0003-4 |bibcode=2019MGRv....1...25C |issn=2661-863X }}</ref> northern ranges of North America's [[Rocky Mountains]],<ref>{{cite journal |last1=Davis|first1=P. Thompson |last2=Menounos |first2=Brian |last3=Osborn |first3=Gerald |date=2009-10-01 |title=Holocene and latest Pleistocene alpine glacier fluctuations: a global perspective |journal=[[Quaternary Science Reviews]] |volume=28 |issue=21 |pages=2021–2033 |doi=10.1016/j.quascirev.2009.05.020|bibcode=2009QSRv...28.2021D}}</ref><ref>{{Cite journal |last1=Osborn |first1=Gerald |last2=Gerloff |first2=Lisa |date=1 January 1997 |title=Latest pleistocene and early Holocene fluctuations of glaciers in the Canadian and northern American Rockies |journal=[[Quaternary International]] |volume=38 |pages=7–19 |doi=10.1016/s1040-6182(96)00026-2 |bibcode=1997QuInt..38....7O}}</ref><ref>{{cite journal |last=Kovanen |first=Dori J. |date=2002-06-01|title=Morphologic and stratigraphic evidence for Allerød and Younger Dryas age glacier fluctuations of the Cordilleran ice sheet, British Columbia, Canada, and northwest Washington, U.S.A |journal=[[Boreas (journal)|Boreas]] |volume=31 |issue=2 |pages=163–184 |doi=10.1111/j.1502-3885.2002.tb01064.x |s2cid=129896627 |issn=1502-3885|doi-access=free |bibcode=2002Borea..31..163K }}</ref> [[Two Creeks Buried Forest State Natural Area|Two Creeks Buried Forest]] in [[Wisconsin]] and western parts of the [[New York State]],<ref>{{Cite journal |last1=Young |first1=Richard A. |last2=Gordon |first2=Lee M. |last3=Owen |first3=Lewis A. |last4=Huot |first4=Sebastien |last5=Zerfas |first5=Timothy D. |date=17 November 2020 |title=Evidence for a late glacial advance near the beginning of the Younger Dryas in western New York State: An event postdating the record for local Laurentide ice sheet recession |journal=[[Geosphere (journal)|Geosphere]] |volume=17 |issue=1 |pages=271–305 |doi=10.1130/ges02257.1 |s2cid=228885304 |issn=1553-040X|doi-access=free }}</ref> and in the Pacific Northwest,<ref>{{cite journal |last=Friele |first=P.A. |author2=Clague, J.J. |year=2002 |title=Younger Dryas readvance in Squamish river valley, southern Coast mountains, British Columbia |journal=[[Quaternary Science Reviews]] |volume=21 |issue=18–19 |pages=1925–1933 |doi=10.1016/S0277-3791(02)00081-1 |bibcode = 2002QSRv...21.1925F }}</ref> including the [[Cascade Range]].<ref>{{Cite journal |last=Heine |first=Jan T. |date=1998-12-01 |journal=[[Quaternary Science Reviews]] |volume=17 |issue=12 |pages=1139–1148 |doi=10.1016/s0277-3791(97)00077-2 |bibcode=1998QSRv...17.1139H |title=Extent, timing, and climatic implications of glacier advances Mount Rainier, Washington, U.S.A., at the Pleistocene/Holocene transition}}</ref> The entire [[Laurentide ice sheet]] had advanced between west [[Lake Superior]] and southeast [[Quebec]], leaving behind a layer of rock debris ([[moraine]]) dated to this period.<ref>{{cite journal |last1=Lowell |first1=Thomas V. |last2=Larson |first2=Graham J. |last3=Hughes |first3=John D. |last4=Denton |first4=George H. |date=25 March 1999 |title=Age verification of the Lake Gribben forest bed and the Younger Dryas advance of the Laurentide ice sheet |journal=[[Canadian Journal of Earth Sciences]] |volume=36 |issue=3 |pages=383–393 |doi=10.1139/e98-095 |issn=0008-4077 |bibcode=1999CaJES..36..383L}}</ref> Southeastern Alaska appears to have escaped glaciation; speleothem calcite deposition continued in the region despite being retarded, indicating the absence of permafrost and glaciation.<ref>{{Cite journal |last=Wilcox |first=Paul S. |last2=Dorale |first2=Jeffrey A. |last3=Baichtal |first3=James F. |last4=Spötl |first4=Christoph |last5=Fowell |first5=Sarah J. |last6=Edwards |first6=R. Lawrence |last7=Kovarik |first7=Johanna L. |date=27 May 2019 |title=Millennial-scale glacial climate variability in Southeastern Alaska follows Dansgaard-Oeschger cyclicity |url=https://www.nature.com/articles/s41598-019-44231-1 |journal=[[Scientific Reports]] |language=en |volume=9 |issue=1 |pages=7880 |doi=10.1038/s41598-019-44231-1 |issn=2045-2322 |access-date=8 November 2024}}</ref> 

On the other hand, the warming of the Southern Hemisphere led to ice loss in Antarctica, South America and New Zealand.<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2010/09/100908132214.htm|archive-url=https://web.archive.org/web/20100911052653/https://www.sciencedaily.com/releases/2010/09/100908132214.htm|url-status=dead |title=New clue to how last ice age ended|archive-date=11 September 2010|website=ScienceDaily}}</ref><ref name="Carlson2013" /> Moreover, while Greenland as a whole had cooled, glaciers had only grown in the north of the island,<ref>{{Cite journal |last1=Larsen |first1=Nicolaj K. |last2=Funder |first2=Svend |last3=Linge |first3=Henriette |last4=Möller |first4=Per |last5=Schomacker |first5=Anders |last6=Fabel |first6=Derek |last7=Xu |first7=Sheng |last8=Kjær |first8=Kurt H. |date=1 September 2016 |title=A Younger Dryas re-advance of local glaciers in north Greenland |url=https://www.sciencedirect.com/science/article/pii/S0277379115301578 |journal=[[Quaternary Science Reviews]] |series=Special Issue: PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways) |volume=147 |pages=47–58 |doi=10.1016/j.quascirev.2015.10.036 |bibcode=2016QSRv..147...47L |issn=0277-3791 }}</ref> and they had retreated from the rest of Greenland's coasts. This was likely driven by the strengthened [[Irminger Current]].<ref name="Rainsley2018">{{Cite journal |last1=Rainsley |first1=Eleanor |last2=Menviel |first2=Laurie |last3=Fogwill |first3=Christopher J. |last4=Turney |first4=Chris S. M. |last5=Hughes |first5=Anna L. C. |last6=Rood |first6=Dylan H. |date=2018-08-09 |title=Greenland ice mass loss during the Younger Dryas driven by Atlantic Meridional Overturning Circulation feedbacks |journal=[[Scientific Reports]] |language=en |volume=8 |issue=1 |page=11307 |doi=10.1038/s41598-018-29226-8 |issn=2045-2322 |pmc=6085367 |pmid=30093676 |bibcode=2018NatSR...811307R }}</ref> The [[Jabllanica]] mountain range in the Balkans also experienced ice loss and glacial retreat: this was likely caused by the drop in annual precipitation, which would have otherwise frozen and helped to maintain the glaciers.<ref>{{Cite journal |last1=Ruszkiczay-Rüdiger |first1=Zsófia |last2=Kern |first2=Zoltán |last3=Temovski |first3=Marjan |last4=Madarász |first4=Balázs |last5=Milevski |first5=Ivica |last6=Braucher |first6=Régis |date=15 February 2020 |title=Last deglaciation in the central Balkan Peninsula: Geochronological evidence from the Jablanica Mt. (North Macedonia) |journal=[[Geomorphology (journal)|Geomorphology]] |volume=351 |page=106985 |doi=10.1016/j.geomorph.2019.106985 |bibcode=2020Geomo.35106985R |issn=0169-555X }}</ref> Unlike now, the glaciers were still present in northern [[Scotland]], but they had thinned during the Younger Dryas.<ref>{{cite book |title=The British Palaeolithic: Human Societies at the Edge of the Pleistocene World |first1=Paul |last1=Pettit |first2=Mark |last2=White |page=477 |publisher=Routledge |year=2012 |location=Abingdon, UK |isbn=978-0-415-67455-3}}</ref>

The amount of water contained within glaciers directly influences global sea levels - [[sea level rise]] occurs if the glaciers retreat, and it drops if glaciers grow. Altogether, there appears to have been little change in sea level throughout the Younger Dryas.<ref name="Shakun2012" /> This is in contrast to rapid increases before and after, such as the [[Meltwater Pulse 1A]].<ref name="Shakun2012" /> On the coasts, glacier advance and retreat also affects [[relative sea level]]. Western [[Norway]] experienced a relative sea level rise of {{cvt|10|m|ft|frac=3}} as the [[Scandinavian ice sheet]] advanced.<ref>{{Cite journal |last1=Lohne |first1=Øystein S. |last2=Bondevik |first2=Stein |last3=Mangerud |first3=Jan |last4=Schrader |first4=Hans |date=July 2004 |title=Calendar year age estimates of Allerød–Younger Dryas sea-level oscillations at Os, western Norway |journal=[[Journal of Quaternary Science]] |language=en |volume=19 |issue=5 |pages=443–464 |doi=10.1002/jqs.846 |bibcode=2004JQS....19..443L |hdl=1956/734 |s2cid=53140679 |issn=0267-8179 }}</ref><ref name="Lohne2007" /> Notably, ice sheet advance in this area appears to have begun about 600 years before the global onset of the Younger Dryas.<ref name="Lohne2007">{{cite journal | last1 = Lohne | first1 = Ø.S. | last2 = Bondevik | first2 = S. | last3 = Mangeruda | first3 = J. | last4 = Svendsena | first4 = J.I. | year = 2007 | title = Sea-level fluctuations imply that the Younger Dryas ice-sheet expansion in western Norway commenced during the Allerød | journal = [[Quaternary Science Reviews]] | volume = 26 | issue = 17–18| pages = 2128–2151 | doi=10.1016/j.quascirev.2007.04.008 | bibcode = 2007QSRv...26.2128L | hdl = 1956/1179 | hdl-access = free }}</ref> Underwater, the deposits of [[methane clathrate]] - methane frozen into ice - remained stable throughout the Younger Dryas, including during the rapid warming as it ended.<ref>{{Cite journal |last=Sowers |first=Todd |date=2006-02-10 |title=Late Quaternary Atmospheric CH 4 Isotope Record Suggests Marine Clathrates Are Stable  |journal=[[Science (journal)|Science]] |language=en |volume=311 |issue=5762 |pages=838–840 |doi=10.1126/science.1121235 |pmid=16469923 |s2cid=38790253 |issn=0036-8075 }}</ref>

=== Weather systems ===
As the Northern Hemisphere cooled and the Southern Hemisphere warmed, the [[thermal equator]] would have shifted to the south. Because [[trade winds]] from either hemisphere cancel each other out above the thermal equator in a calm, heavily clouded area known as the [[Intertropical Convergence Zone]] (ITCZ), a change in its position affects wind patterns elsewhere. For instance, in [[East Africa]], the sediments of [[Lake Tanganyika]] were mixed less strongly during this period, indicating weaker wind systems in this area.<ref>{{Cite journal |last1=Tierney |first1=Jessica E. |last2=Russell |first2=James M. |date=11 August 2007 |title=Abrupt climate change in southeast tropical Africa influenced by Indian monsoon variability and ITCZ migration |journal=[[Geophysical Research Letters]] |language=en |volume=34 |issue=15 |doi=10.1029/2007GL029508 |bibcode=2007GeoRL..3415709T |s2cid=129722161 |issn=0094-8276 }}</ref> Shifts in atmospheric patterns are believed to be the main reason why Northern Hemisphere summers generally did not cool during the Younger Dryas.<ref name="Schenk2018" />

Since winds carry moisture in the form of clouds, these changes also affect [[precipitation]]. Thus, evidence from the pollen record shows that some areas have become very arid, including Scotland,<ref>{{Cite journal |last1=Golledge |first1=Nicholas |last2=Hubbard |first2=Alun |last3=Bradwell |first3=Tom |date=30 June 2009 |title=Influence of seasonality on glacier mass balance, and implications for palaeoclimate reconstructions |journal=[[Climate Dynamics]] |language=en |volume=35 |issue=5 |pages=757–770 |doi=10.1007/s00382-009-0616-6 |s2cid=129774709 |issn=0930-7575 }}</ref> the North American [[Midwest]], <ref>{{cite journal |last1=Dorale |first1=J.A. |last2=Wozniak |first2=L.A. |last3=Bettis |first3=E.A. |last4=Carpenter |first4=S.J. |last5=Mandel |first5=R.D. |last6=Hajic |first6=E.R. |last7=Lopinot |first7=N.H. |last8=Ray |first8=J.H. |title=Isotopic evidence for Younger Dryas aridity in the North American midcontinent|journal=Geology|volume=38|issue=6|pages=519–522|doi=10.1130/g30781.1|bibcode=2010Geo....38..519D|year=2010}}</ref> [[Anatolia]] and southern [[China]].<ref>{{Cite journal |last1=Dean |first1=Jonathan R. |last2=Jones |first2=Matthew D. |last3=Leng |first3=Melanie J. |last4=Noble |first4=Stephen R. |last5=Metcalfe |first5=Sarah E. |last6=Sloane |first6=Hilary J. |last7=Sahy |first7=Diana |last8=Eastwood |first8=Warren J. |last9=Roberts |first9=C. Neil |date=15 September 2015 |title=Eastern Mediterranean hydroclimate over the late glacial and Holocene, reconstructed from the sediments of Nar lake, central Turkey, using stable isotopes and carbonate mineralogy |journal=[[Quaternary Science Reviews]] |volume=124 |pages=162–174 |doi=10.1016/j.quascirev.2015.07.023 |bibcode=2015QSRv..124..162D |hdl=10026.1/3808 |issn=0277-3791 |url=https://nottingham-repository.worktribe.com/file/761164/1/Dean%20et%20al.%202015%20QSR.pdf }}</ref><ref>{{Cite journal |last1=Fleitmann |first1=D. |last2=Cheng |first2=H. |last3=Badertscher |first3=S. |last4=Edwards |first4=R. L. |last5=Mudelsee |first5=M. |last6=Göktürk |first6=O. M. |last7=Fankhauser |first7=A. |last8=Pickering |first8=R. |last9=Raible |first9=C. C. |last10=Matter |first10=A. |last11=Kramers |first11=J. |last12=Tüysüz |first12=O. |date=6 October 2009 |title=Timing and climatic impact of Greenland interstadials recorded in stalagmites from northern Turkey |journal=[[Geophysical Research Letters]] |language=en |volume=36 |issue=19 |doi=10.1029/2009GL040050 |bibcode=2009GeoRL..3619707F |issn=0094-8276 }}</ref><ref name="Hong2014">{{cite journal |last1=Hong |first1=Bing |last2=Hong |first2=Yetang |last3=Uchida |first3=Masao |last4=Shibata |first4=Yasuyuki |last5=Cai |first5=Cheng |last6=Peng |first6=Haijun |last7=Zhu |first7=Yongxuan |last8=Wang |first8=Yu |last9=Yuan |first9=Linggui |date=1 August 2014 |title=Abrupt variations of Indian and East Asian summer monsoons during the last deglacial stadial and interstadial |url= |journal=[[Quaternary Science Reviews]] |volume=97 |pages=58–70 |doi=10.1016/j.quascirev.2014.05.006 |bibcode=2014QSRv...97...58H }}</ref> As North Africa, including the [[Sahara Desert]], became drier, the amount of dust blown by wind had also increased.<ref name="Carlson2013" /> Other areas became wetter including northern China<ref name="Hong2014"/> (possibly excepting the [[Shanxi]] region)<ref>{{cite journal |last1=Zhang |first1=Zhiping |last2=Liu |first2=Jianbao |last3=Chen |first3=Shengqian |last4=Chen |first4=Jie |last5=Zhang |first5=Shanjia |last6=Xia |first6=Huan |last7=Shen |first7=Zhongwei |last8=Wu |first8=Duo |last9=Chen |first9=Fahu |date=27 June 2018 |title=Nonlagged Response of Vegetation to Climate Change During the Younger Dryas: Evidence from High-Resolution Multiproxy Records from an Alpine Lake in Northern China |journal=[[Journal of Geophysical Research]] |volume=123 |issue=14 |pages=7065–7075 |doi=10.1029/2018JD028752 |bibcode=2018JGRD..123.7065Z |s2cid=134259679 |doi-access=free }}</ref>
<!-- In what is now [[Hesse]], the early part of the Younger Dryas saw the development of a multi-channel braidplain. During the later Younger Dryas, this braidplain reverted back to a fluvial system of straight and meandering rivers akin to that which had been the norm during the Allerød oscillation.<ref>{{Cite journal |last1=Litt |first1=Thomas |last2=Schmincke |first2=Hans-Ulrich |last3=Kromer |first3=Bernd |date=1 January 2003 |title=Environmental response to climatic and volcanic events in central Europe during the Weichselian Lateglacial  |journal=[[Quaternary Science Reviews]] |series=Environmental response to climate and human impact in central Eur ope during the last 15000 years - a German contribution to PAGES-PEPIII |volume=22 |issue=1 |pages=7–32 |doi=10.1016/S0277-3791(02)00180-4 |bibcode=2003QSRv...22....7L |issn=0277-3791 }}</ref> -->