Editing Ice (section)

==Impacts of climate change==
{{See also|Climate change in the Arctic|Climate change in Antarctica}}

===Historical===

[[File:20210125 The Cryosphere - Floating and grounded ice - imbalance - climate change.png|thumb|upright=1.35| Earth lost 28 trillion tonnes of ice between 1994 and 2017, with melting grounded ice (ice sheets and glaciers) raising the global sea level by 34.6 ±3.1 mm.<ref name="Slater2021" /> The rate of ice loss has risen by 57% since the 1990s−from 0.8 to 1.2 trillion tonnes per year.<ref name="Slater2021" />]]

[[File:Slater 2021 global ice loss.png|thumb|On average, climate change has lowered the thickness of land ice with every year, and reduced the extent of sea ice cover.<ref name="Slater2021" />]]

[[Greenhouse gas emissions]] from human activities unbalance the [[Earth's energy budget]] and so cause an accumulation of [[heat]].<ref name="vonSchuckmann2023" /> About 90% of that heat is added to [[ocean heat content]], 1% is retained in the atmosphere and 3-4% goes to melt major parts of the cryosphere.<ref name="vonSchuckmann2023">{{cite journal |last1=von Schuckmann |first1=Karina |last2=Minière |first2=Audrey. |last3=Gues |first3=Flora |last4=Cuesta-Valero |first4=Francisco José |last5=Kirchengast |first5=Gottfried |last6=Adusumilli |first6=Susheel |last7=Straneo |first7=Flammetta |last8=Ablain |first8=Michaël |last9=Allen |first9=Richard P. |last10=Barker |first10=Paul M. |title=Heat stored in the Earth system 1960-2020: where does the energy go? |journal=Earth System Science Data |date=17 April 2023 |doi=10.5194/essd-15-1675-2023 |doi-access=free |volume=15 |issue=4 |pages=1675-1709 [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]|bibcode=2023ESSD...15.1675V |hdl=20.500.11850/619535 |hdl-access=free }}</ref> Between 1994 and 2017, 28 trillion tonnes of ice were lost around the globe as the result.<ref name="Slater2021" /> [[Arctic sea ice decline]] accounted for the single largest loss (7.6 trillion tonnes), followed by the melting of Antarctica's [[ice shelves]] (6.5 trillion tonnes), the [[Retreat of glaciers since 1850|retreat of mountain glaciers]] (6.1 trillion tonnes), the melting of the [[Greenland ice sheet]] (3.8 trillion tonnes) and finally the melting of the [[Antarctic ice sheet]] (2.5 trillion tonnes) and the limited losses of the sea ice in the [[Southern Ocean]] (0.9 trillion tonnes).<ref name="Slater2021">{{cite journal |last1=Slater |first1=Thomas |last2=Lawrence |first2=Isobel R. |last3=Otosaka |first3=Inès N. |last4=Shepherd |first4=Andrew |last5=Gourmelen |first5=Noel |last6=Jakob |first6=Livia |last7=Tepes |first7=Paul |last8=Gilbert |first8=Lin |last9=Nienow |first9=Peter |title=Review article: Earth's ice imbalance |journal=The Cryosphere |date=25 Jan 2021 |doi=10.5194/tc-15-233-2021 |doi-access=free |volume=15 |issue=1 |pages=233–246 [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]|bibcode=2021TCry...15..233S |hdl=20.500.11820/df343a4d-6b66-4eae-ac3f-f5a35bdeef04 |hdl-access=free }}</ref>

Other than the sea ice (which already displaces water due to [[Archimedes' principle]]), these losses are a major cause of [[sea level rise]] (SLR) and they are expected to intensify in the future. In particular, the melting of the [[West Antarctic ice sheet]] may accelerate substantially as the floating [[ice shelf|ice shelves]] are lost and can no longer buttress the glaciers. This would trigger poorly understood [[marine ice sheet instability]] processes, which could then increase the SLR expected for the end of the century (between {{cvt|30|cm|ft|frac=2}} and {{cvt|1|m|ft|frac=2}}, depending on future warming), by tens of centimeters more.<ref name="IPCC AR6 WG1 Ch.9">{{Cite journal |last1=Fox-Kemper |first1=B. |last2=Hewitt |first2=Helene T. |author2-link=Helene Hewitt |last3=Xiao |first3=C. |last4=Aðalgeirsdóttir |first4=G. |last5=Drijfhout |first5=S. S. |last6=Edwards |first6=T. L. |last7=Golledge |first7=N. R. |last8=Hemer |first8=M. |last9=Kopp |first9=R. E. |last10=Krinner |first10=G. |last11=Mix |first11=A. |date=2021 |editor-last=Masson-Delmotte |editor-first=V. |editor2-last=Zhai |editor2-first=P. |editor3-last=Pirani |editor3-first=A. |editor4-last=Connors |editor4-first=S. L. |editor5-last=Péan |editor5-first=C. |editor6-last=Berger |editor6-first=S. |editor7-last=Caud |editor7-first=N. |editor8-last=Chen |editor8-first=Y. |editor9-last=Goldfarb |editor9-first=L. |title=Chapter 9: Ocean, Cryosphere and Sea Level Change |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter09.pdf |journal=Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |publisher=Cambridge University Press, Cambridge, UK and New York, NY, US }}</ref>{{rp|1302}} 

Ice loss in Greenland and Antarctica also produces large quantities of fresh [[meltwater]], which disrupts the [[Atlantic meridional overturning circulation]] (AMOC) and the [[Southern Ocean overturning circulation]], respectively.<ref name="GTPR2023" /> These two halves of the [[thermohaline circulation]] are very important for the global climate. A continuation of high meltwater flows may cause a severe disruption (up to a point of a "collapse") of either circulation, or even both of them. Either event would be considered an example of [[tipping points in the climate system]], because it would be extremely difficult to reverse.<ref name="GTPR2023">{{cite report |last1=Lenton |first1=T. M. |last2=Armstrong McKay |first2=D.I. |last3=Loriani |first3=S. |last4=Abrams |first4=J.F.  |last5=Lade |first5=S.J. |last6=Donges |first6=J.F. |last7=Milkoreit |first7=M. |last8=Powell |first8=T. |last9=Smith |first9=S.R. |last10=Zimm |first10=C. |last11=Buxton |first11=J.E. |last12=Daube |first12=Bruce C. |last13=Krummel |first13=Paul B. |last14=Loh |first14=Zoë |last15=Luijkx |first15=Ingrid T. |year=2023 |title=The Global Tipping Points Report 2023 |url=https://global-tipping-points.org/download/4608/ |publisher=University of Exeter }}</ref> AMOC is generally not expected to collapse during the 21st century, while there is only limited knowledge about the Southern Ocean circulation.<ref name="IPCC AR6 WG1 Ch.9" />{{rp|1214}}

Another example of ice-related tipping point is permafrost thaw. While the organic content in the permafrost causes {{CO2}} and methane emissions once it thaws and begins to decompose,<ref name="GTPR2023" /> ice melting liqufies the ground, causing anything built above the former permafrost to collapse. By 2050, the economic damages from such infrastructure loss are expected to cost tens of billions of dollars.<ref name="Hjort2022">{{Cite journal |last1=Hjort |first1=Jan |last2=Streletskiy |first2=Dmitry |last3=Doré |first3=Guy |last4=Wu |first4=Qingbai |last5=Bjella |first5=Kevin |last6=Luoto |first6=Miska |date=11 January 2022 |title=Impacts of permafrost degradation on infrastructure |journal=Nature Reviews Earth & Environment |volume=3 |issue=1 |pages=24–38 |doi=10.1038/s43017-021-00247-8|bibcode=2022NRvEE...3...24H |hdl=10138/344541 |s2cid=245917456 |url=http://urn.fi/urn:nbn:fi-fe2022101962575 |hdl-access=free }}</ref>

===Predictions===

[[File:Wunderling_2020_regional_impact.jpg|thumb|Potential regional warming caused by the loss of all land ice outside of East Antarctica, and by the disappearance of Arctic sea ice every year starting from June.<ref name="Wunderling2020" /> While plausible, consistent sea ice loss would likely require relatively high warming,<ref name="Sigmond2018" /> and the loss of all ice in Greenland would require multiple millennia.<ref name="ArmstrongMcKay2022" /><ref name="ArmstrongMcKayExplainer" />]]

In the future, the [[Arctic Ocean]] is likely to lose effectively all of its sea ice during at least some Septembers (the end of the ice melting season), although some of the ice would refreeze during the winter. I.e. an ice-free September is likely to occur once in every 40 years if global warming is at {{convert|1.5|C-change|F-change}}, but would occur once in every 8 years at {{convert|2|C-change|F-change}} and once in every 1.5 years at {{convert|3|C-change|F-change}}.<ref name="Sigmond2018">{{Cite journal |last1=Sigmond |first1=Michael |last2=Fyfe  |first2=John C. |last3=Swart  |first3=Neil C. |date=2 April 2018 |title=Ice-free Arctic projections under the Paris Agreement |url=https://www.nature.com/articles/s41558-018-0124-y.epdf?sharing_token=s5CzjtDj8gf0ZmN6CCHGztRgN0jAjWel9jnR3ZoTv0PLVuAXOp2dJlBdNTJtKWqWAUYJ9Ns6JXBlxiHaipJXlrKpbiBcmkhRc42ypYk5a3aeceQ5dF5hV39PYKz05y5seLV8NH9jDQsSxYOgWrLL-CjbZkxrUf6gYwBnx-vAhRL3KTUq_7I1sz5MHuQESHzcuFa8mIqycanI0sYAgJoCzHIjO-WCVh51qA0aONgHJ5s%3D&tracking_referrer=interactive.carbonbrief.org |journal=Nature Climate Change |language=en |volume=2 |issue=5 |pages=404–408 |doi=10.1038/s41558-018-0124-y|bibcode=2018NatCC...8..404S |s2cid=90444686 }}</ref> This would affect the regional and global climate due to the [[ice-albedo feedback]]. Because ice is highly reflective of solar energy, persistent sea ice cover lowers local temperatures. Once that ice cover melts, the darker ocean waters begin to absorb more heat, which also helps to melt the remaining ice.<ref name="Dai2019">{{Cite journal |last1=Dai |first1=Aiguo |last2=Luo |first2=Dehai |last3=Song |first3=Mirong |last4=Liu |first4=Jiping |date=10 January 2019 |title=Arctic amplification is caused by sea-ice loss under increasing {{CO2}} |journal=Nature Communications |language=en |volume=10 |issue=1 |page=121 |doi=10.1038/s41467-018-07954-9 |pmid=30631051 |pmc=6328634 |bibcode=2019NatCo..10..121D }}</ref>

Global losses of sea ice between 1992 and 2018, almost all of them in the Arctic, have already had the same impact as 10% of [[greenhouse gas]] emissions over the same period.<ref name="Riihelä2021">{{Cite journal |last1=Riihelä |first1=Aku |last2=Bright |first2=Ryan M. |last3=Anttila |first3=Kati |date=28 October 2021 |title=Recent strengthening of snow and ice albedo feedback driven by Antarctic sea-ice loss |journal=Nature Geoscience |language=en |volume=14 |issue=11 |pages=832–836 |doi=10.1038/s41561-021-00841-x |bibcode=2021NatGe..14..832R |hdl=11250/2830682 |hdl-access=free }}</ref> If all the Arctic sea ice was gone every year between June and September ([[polar day]], when the Sun is constantly shining), temperatures in the Arctic would increase by over {{convert|1.5|C-change|F-change}}, while the global temperatures would increase by around {{convert|0.19|C-change|F-change}}.<ref name="Wunderling2020">{{Cite journal |last1=Wunderling |first1=Nico |last2=Willeit |first2=Matteo |last3=Donges |first3=Jonathan F. |last4=Winkelmann |first4=Ricarda |date=27 October 2020 |title=Global warming due to loss of large ice masses and Arctic summer sea ice |journal=Nature Communications |language=en |volume=10 |issue=1 |page=5177 |doi=10.1038/s41467-020-18934-3 |pmid=33110092 |pmc=7591863 |bibcode=2020NatCo..11.5177W }}</ref>

[[File:Höning 2023 GIS thresholds.jpg|thumb|upright=1.2|Possible equilibrium states of the Greenland ice sheet in response to different equilibrium carbon dioxide concentrations in [[parts per million]]. Second and third states would result in {{convert|1.8|m|ft|0|abbr=on}} and {{convert|2.4|m|ft|0|abbr=on}} of sea level rise, while the fourth state is equivalent to {{convert|6.9|m|ft|0|abbr=on}}.<ref name="Höning2023">{{Cite journal |last1=Höning |first1=Dennis |last2=Willeit |first2=Matteo |last3=Calov |first3=Reinhard |last4=Klemann |first4=Volker |last5=Bagge |first5=Meike |last6=Ganopolski |first6=Andrey |date=27 March 2023 |title=Multistability and Transient Response of the Greenland Ice Sheet to Anthropogenic CO2 Emissions |journal=Geophysical Research Letters |volume=50 |issue=6 |page=e2022GL101827 |doi=10.1029/2022GL101827 |s2cid=257774870}}</ref>]]

By 2100, at least a quarter of mountain glaciers outside of Greenland and Antarctica would melt,<ref>{{Cite journal |last1=Rounce |first1=David R. |last2=Hock |first2=Regine |last3=Maussion |first3=Fabien |last4=Hugonnet |first4=Romain |last5=Kochtitzky |first5=William |last6=Huss |first6=Matthias |last7=Berthier|first7=Etienne |last8=Brinkerhoff |first8=Douglas |last9=Compagno |first9=Loris |last10=Copland |first10=Luke |last11=Farinotti |first11=Daniel |last12=Menounos |first12=Brian |last13=McNabb |first13=Robert W. |date=5 January 2023 |title=Global glacier change in the 21st century: Every increase in temperature matters |url=https://www.science.org/doi/10.1126/science.abo1324 |journal=Science |language=en |volume=79 |issue=6627 |pages=78–83 |doi=10.1126/science.abo1324 |pmid=36603094 |bibcode=2023Sci...379...78R |s2cid=255441012 |hdl=10852/108771 |hdl-access=free }}</ref> and effectively all ice caps on non-polar mountains are likely to be lost around 200 years after global warming reaches {{convert|2|C-change|F-change}}.<ref name="ArmstrongMcKay2022" /><ref name="ArmstrongMcKayExplainer" /> The West Antarctic ice sheet is highly vulnerable and will likely disappear even if the warming does not progress further,<ref>{{Cite web|url=https://www.science.org/content/article/discovery-recent-antarctic-ice-sheet-collapse-raises-fears-new-global-flood|title=Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood|last=Voosen|first=Paul|date=2018-12-18|website=Science|language=en|access-date=2018-12-28}}</ref><ref name="Carlson2018">{{Cite conference |last1=Carlson |first1=Anders E |last2=Walczak |first2=Maureen H |last3=Beard |first3=Brian L |last4=Laffin |first4=Matthew K |last5=Stoner |first5=Joseph S |last6=Hatfield |first6=Robert G |date=10 December 2018 |title=Absence of the West Antarctic ice sheet during the last interglaciation |url=https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/421418  |conference=American Geophysical Union Fall Meeting }}</ref><ref name="Naughten2023">{{cite journal |last1=A. Naughten |first1=Kaitlin |last2=R. Holland |first2=Paul |last3=De Rydt |first3=Jan|title=Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century |journal=Nature Climate Change |date=23 October 2023 |volume=13 |issue=11 |pages=1222–1228 |doi=10.1038/s41558-023-01818-x |s2cid=264476246 |doi-access=free |bibcode=2023NatCC..13.1222N }}</ref><ref name="Lau2023">{{Cite journal |last1=Lau |first1=Sally C. Y. |last2=Wilson |first2=Nerida G. |last3=Golledge |first3=Nicholas R.  |last4=Naish |first4=Tim R. |last5=Watts |first5=Phillip C. |last6=Silva |first6=Catarina N. S. |last7=Cooke |first7=Ira R. |last8=Allcock |first8=A. Louise |last9=Mark |first9=Felix C. |last10=Linse |first10=Katrin |date=21 December 2023 |title=Genomic evidence for West Antarctic Ice Sheet collapse during the Last Interglacial |journal=Science |language=en |volume=382 |issue=6677 |pages=1384–1389 |doi=10.1126/science.ade0664 |pmid=38127761 |bibcode=2023Sci...382.1384L |s2cid=266436146 |url=https://epic.awi.de/id/eprint/58369/1/science.ade0664%281%29.pdf }}</ref> although it could take around 2,000 years before its loss is complete.<ref name="ArmstrongMcKay2022">{{Cite journal |last1=Armstrong McKay |first1=David|last2=Abrams |first2=Jesse |last3=Winkelmann |first3=Ricarda |last4=Sakschewski |first4=Boris |last5=Loriani |first5=Sina |last6=Fetzer |first6=Ingo|last7=Cornell|first7=Sarah |last8=Rockström |first8=Johan |last9=Staal |first9=Arie |last10=Lenton |first10=Timothy |date=9 September 2022 |title=Exceeding 1.5°C global warming could trigger multiple climate tipping points |url=https://www.science.org/doi/10.1126/science.abn7950 |journal=Science |language=en |volume=377 |issue=6611 |pages=eabn7950 |doi=10.1126/science.abn7950 |pmid=36074831 |hdl=10871/131584 |s2cid=252161375 |issn=0036-8075|hdl-access=free }}</ref><ref name="ArmstrongMcKayExplainer">{{Cite web |last=Armstrong McKay |first=David |date=9 September 2022 |title=Exceeding 1.5°C global warming could trigger multiple climate tipping points – paper explainer |url=https://climatetippingpoints.info/2022/09/09/climate-tipping-points-reassessment-explainer/ |access-date=2 October 2022 |website=climatetippingpoints.info |language=en}}</ref> The Greenland ice sheet will most likely be lost with the sustained warming between {{convert|1.7|C-change|F-change}} and {{convert|2.3|C-change|F-change}},<ref name="Bochow2023">{{cite journal |last1=Bochow |first1=Nils |last2=Poltronieri |first2=Anna |last3=Robinson |first3=Alexander |last4=Montoya |first4=Marisa |last5=Rypdal |first5=Martin |last6=Boers |first6=Niklas |date=18 October 2023 |title=Overshooting the critical threshold for the Greenland ice sheet |journal=Nature |volume=622 |issue=7983 |pages=528–536 |bibcode=2023Natur.622..528B |doi=10.1038/s41586-023-06503-9 |pmc=10584691 |pmid=37853149}}</ref> although its total loss requires around 10,000 years.<ref name="ArmstrongMcKay2022" /><ref name="ArmstrongMcKayExplainer" /> Finally, the [[East Antarctic ice sheet]] will take at least 10,000 years to melt entirely, which requires a warming of between {{convert|5|C-change|F-change}} and {{convert|10|C-change|F-change}}.<ref name="ArmstrongMcKay2022" /><ref name="ArmstrongMcKayExplainer" />

If all the ice on Earth melted, it would result in about {{Convert|70|m|ftin|abbr=on}} of sea level rise,<ref>{{cite web |title=How would sea level change if all glaciers melted? |url=https://www.usgs.gov/faqs/how-would-sea-level-change-if-all-glaciers-melted |website=United States Geological Survey |date=23 September 2021 |access-date=15 January 2024 }}</ref> with some {{Convert|53.3|m|ftin|abbr=on}} coming from East Antarctica.<ref name="Fretwell2013">{{cite journal |last1=Fretwell |first1=P. |last2=Pritchard |first2=H. D. |last3=Vaughan |first3=D. G. |last4=Bamber |first4=J. L. |last5=Barrand |first5=N. E. |last6=Bell |first6=R. |last7=Bianchi |first7=C. |last8=Bingham |first8=R. G. |last9=Blankenship |first9=D. D. |last10=Casassa |first10=G. |last11=Catania |first11=G. |last12=Callens |first12=D. |last13=Conway |first13=H. |last14=Cook |first14=A. J. |last15=Corr |first15=H. F. J. |last16=Damaske |first16=D. |last17=Damm |first17=V. |last18=Ferraccioli |first18=F. |last19=Forsberg |first19=R. |last20=Fujita |first20=S. |last21=Gim |first21=Y. |last22=Gogineni |first22=P. |last23=Griggs |first23=J. A. |last24=Hindmarsh |first24=R. C. A. |last25=Holmlund |first25=P. |last26=Holt |first26=J. W. |last27=Jacobel |first27=R. W. |last28=Jenkins |first28=A. |last29=Jokat |first29=W. |last30=Jordan |first30=T. |last31=King |first31=E. C. |last32=Kohler |first32=J. |last33=Krabill |first33=W. |last34=Riger-Kusk |first34=M. |last35=Langley |first35=K. A. |last36=Leitchenkov |first36=G. |last37=Leuschen |first37=C. |last38=Luyendyk |first38=B. P. |last39=Matsuoka |first39=K. |last40=Mouginot |first40=J. |last41=Nitsche |first41=F. O. |last42=Nogi |first42=Y. |last43=Nost |first43=O. A. |last44=Popov |first44=S. V. |last45=Rignot |first45=E. |last46=Rippin |first46=D. M. |last47=Rivera |first47=A. |last48=Roberts |first48=J. |last49=Ross |first49=N. |last50=Siegert |first50=M. J. |last51=Smith |first51=A. M. |last52=Steinhage |first52=D. |last53=Studinger |first53=M. |last54=Sun |first54=B. |last55=Tinto |first55=B. K. |last56=Welch |first56=B. C. |last57=Wilson |first57=D. |last58=Young |first58=D. A. |last59=Xiangbin |first59=C. |last60=Zirizzotti |first60=A. |title=Bedmap2: improved ice bed, surface and thickness datasets for Antarctica |journal=The Cryosphere |date=28 February 2013 |volume=7 |issue=1 |pages=375–393 |doi=10.5194/tc-7-375-2013 |bibcode=2013TCry....7..375F |doi-access=free |hdl=1808/18763 |hdl-access=free }}</ref> Due to [[isostatic rebound]], the ice-free land would eventually become {{Convert|301|m|ftin|abbr=on}} higher in Greenland and {{Convert|494|m|ftin|abbr=on}} in Antarctica, on average. Areas in the center of each landmass would become up to {{Convert|783|m|ftin|abbr=on}} and {{Convert|936|m|ftin|abbr=on}} higher, respectively.<ref>{{Cite journal |last1=Paxman |first1=Guy J. G. |last2=Austermann |first2=Jacqueline |last3=Hollyday |first3=Andrew |date=6 July 2022 |title=Total isostatic response to the complete unloading of the Greenland and Antarctic Ice Sheets |journal=Scientific Reports |volume=12 |issue=1 |page=11399 |doi=10.1038/s41598-022-15440-y |pmid=35794143 |pmc=9259639 |bibcode=2022NatSR..1211399P }}</ref> The impact on global temperatures from losing West Antartica, mountain glaciers and the Greenland ice sheet is estimated at {{convert|0.05|C-change|F-change}}, {{convert|0.08|C-change|F-change}} and {{convert|0.13|C-change|F-change}}, respectively,<ref name="Wunderling2020" /> while the lack of the East Antarctic ice sheet would increase the temperatures by {{convert|0.6|C-change|F-change}}.<ref name="ArmstrongMcKay2022" /><ref name="ArmstrongMcKayExplainer" />