Editing Ice (section)

===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>