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Sea level rise: Difference between revisions - Wikipedia
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Sea level rise: Difference between revisions

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<noinclude>[[File:1880- Global average sea level rise (SLR) - annually.svg |thumb|upright=1.35 |The global average sea level has risen about {{convert|250|mm|in}} since 1880.<ref name=EPA_SLR_202207>{{cite web |title=Climate Change Indicators: Sea Level / Figure 1. Absolute Sea Level Change |url=https://www.epa.gov/climate-indicators/climate-change-indicators-sea-level |website=EPA.gov |publisher=U.S. Environmental Protection Agency (EPA) |archive-url=https://web.archive.org/web/20230904035800/https://www.epa.gov/climate-indicators/climate-change-indicators-sea-level |archive-date=4 September 2023 |date=July 2022 |quote=Data sources: CSIRO, 2017. NOAA, 2022. |url-status=live }}</ref>]]</noinclude>
 
Between 1901 and 2018, average global [[sea level]] rose by {{cvt|15|–|25|cm|in|frac=2}}, with an averageincrease of {{convert|1|-|2.3|mm|abbr=on}} per year since the 1970.<ref name="SROCC_SPM_20190925">IPCC, 2019:AR6 [https://www.ipcc.ch/site/assets/uploads/sites/3/2022/03/01_SROCC_SPM_FINAL.pdfWG1 Summary for Policymakers]Ch.9" In: [https://www.ipcc.ch/srocc/>{{rp|1216}} IPCCThis Specialis Reportfaster onthan theit Oceanever androse Cryosphereover inthe apast Changing Climate] H.-O. Pörtner3,000 D. C. Robertsyears, V.if Masson-Delmotte,not Plonger.<ref Zhai,name="IPCC M.AR6 Tignor,WG1 ECh.9" Poloczanska, K. Mintenbeck, A. Alegría, M.&nbsp;Nicolai, A. Okem, J. Petzold, B. Rama, N. M. Weyer (eds.). Cambridge University Press, Cambridge, UK and New York, New York, US. https://doi.org/10.1017/9781009157964.001.</ref>{{rp|1216}} This rate accelerated to {{convert|4.62|mm|abbr=on}}/yr for the decade 2013–2022.<ref name=WMO_20230421/> [[Climate change]] due to human activities is the main cause.<ref name="IPCC_2021_WGI_SPM" />{{rp|5,8}} Between 1993 and 2018, [[thermal expansion]] of water accounted for 42% of sea level rise. Melting [[temperate glacier]]s accounted for 21%, while polar glaciers in [[Greenland]] accounted for 15% and those in [[Antarctica]] for 8%.<ref name="WCRP2018">{{cite journal |author=WCRP Global Sea Level Budget Group |year=2018 |title=Global sea-level budget 1993–present |journal=Earth System Science Data |volume=10 |issue=3 |pages=1551–1590 |bibcode=2018ESSD...10.1551W |doi=10.5194/essd-10-1551-2018 |quote=This corresponds to a mean sea-level rise of about 7.5 cm over the whole altimetry period. More importantly, the GMSL curve shows a net acceleration, estimated to be at 0.08mm/yr<sup>2</sup>. |doi-access=free}}</ref>{{Rp|1576}}
 
Sea level rise lags behind changes in the [[Earth]]'s temperature, and sea level rise will therefore continue to accelerate between now and 2050 in response to warming that has already happened.<ref name="us nrc 2011 long term slr">{{cite book |author=((National Academies of Sciences, Engineering, and Medicine)) |year=2011 |quote=Box SYN-1: Sustained warming could lead to severe impacts |chapter-url=https://nap.nationalacademies.org/read/12877/chapter/3 |page=[https://nap.nationalacademies.org/read/12877/chapter/3#5 5] |chapter=Synopsis |title=Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia |location=Washington, DC |publisher=The National Academies Press |doi=10.17226/12877|isbn=978-0-309-15176-4 }}</ref> What happens after that depends on human [[greenhouse gas emissions]]. Sea level rise would slow between 2050 and 2100 if there are very deep cuts in emissions. It could then reach slightly over {{cvt|30|cm|ft|frac=2}} from now by 2100. With high emissions it would accelerate. It could rise by {{cvt|1.01|m|ft|frac=3}} or even {{cvt|1.6|m|ft|frac=3}} by then.<ref name="IPCC_2021_WGI_SPM" /><ref name="IPCC AR6 WG1 Ch.9" />{{Rp|page=1302}} In the long run, sea level rise would amount to {{convert|2-3|m|ft|0|abbr=on}} over the next 2000 years if warming amounts to {{convert|1.5|C-change|F-change}}. It would be {{convert|19-22|m|ft}} if warming peaks at {{convert|5|C-change|F-change}}.<ref name="IPCC_2021_WGI_SPM">IPCC, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf Summary for Policymakers]. In: [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, New York, US, pp. 3−32, doi:10.1017/9781009157896.001.</ref>{{rp|21}}
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== Observations ==
[[File:Sea surface height change from 1992 to 2019.webm|thumb|upright=1.35| {{center|Sea surface height change from 1992 to 2019 – NASA}} The visualization is based on data collected from the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellites. Blue regions are where sea level has gone down, and orange/red regions are where sea level has risen.<ref name="NASA2020">[https://svs.gsfc.nasa.gov/4853 27-year Sea Level Rise – TOPEX/JASON] ''NASA Visualization Studio'', 5 November 2020. {{PD-notice}}</ref>]]
Between 1901 and 2018, the global mean sea level rose by about {{convert|20|cm|abbr=on}}.<ref name="IPCC_2021_WGI_SPM" /> More precise data gathered from satellite [[radar]] measurements found aan riseincrease of {{convert|7.5|cm|abbr=on}} from 1993 to 2017 (average of {{convert|2.9|mm|abbr=on}}/yr).<ref name="WCRP2018" /> This accelerated to {{convert|4.62|mm|abbr=on}}/yr for 2013–2022.<ref name="WMO_20230421">{{cite web |date=21 April 2023 |title=WMO annual report highlights continuous advance of climate change |url=https://wmo.int/news/media-centre/wmo-annual-report-highlights-continuous-advance-of-climate-change |publisher=World Meteorological Organization |quote=Press Release Number: 21042023.}}</ref> [[Paleoclimate]] data shows that this rate of sea level rise is the fastest it had been over at least the past 3,000 years.<ref name="IPCC AR6 WG1 Ch.9" />{{rp|1216}}
 
=== Regional variations ===
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== Projections ==
[[File:2050 Projected sea level rise - United States coasts - NOAA.svg|thumb|upright=1.35|[[NOAA]] predicts different levels of sea level rise through 2050 for several US coastlines.<ref name=NOAA-2022 />|alt=A comparison of SLR in six parts of the US. The Gulf Coast and East Coast see the most SLR, whereas the West Coast the least]]▼
There are two complementary ways to model sea level rise (SLR) and [[General circulation model#Projections|project]] the future. The first uses process-based modeling. This combines all relevant and well-understood physical processes in a global physical model. This approach calculates the contributions of ice sheets with an [[ice-sheet model]] and computes rising sea temperature and expansion with a [[general circulation model]]. The processes are imperfectly understood, but this approach has the advantage of predicting non-linearities and long delays in the response, which studies of the recent past will miss.
 
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The melting of all the [[ice]] in West Antarctica would increase the total sea level rise to {{convert|4.3|m|ftin|abbr=on}}.<ref name="BEDMAP2-2013">{{cite journal |last1=Fretwell |first1=P. |display-authors=et al |title=Bedmap2: improved ice bed, surface and thickness datasets for Antarctica |journal=The Cryosphere |volume=7 |issue=1 |page=390 |date=28 February 2013 |url=http://www.the-cryosphere.net/7/375/2013/tc-7-375-2013.pdf |access-date=6 January 2014 |doi=10.5194/tc-7-375-2013 |bibcode=2013TCry....7..375F |s2cid=13129041 |doi-access=free |archive-date=16 February 2020 |archive-url=https://web.archive.org/web/20200216072841/https://www.the-cryosphere.net/7/375/2013/tc-7-375-2013.pdf |url-status=live }}</ref> However, mountain [[ice cap]]s not in contact with water are less vulnerable than the majority of the ice sheet, which is located below the sea level.<ref name="Hein2016">{{Cite journal |last1=Hein |first1=Andrew S. |last2=Woodward |first2=John |last3=Marrero |first3=Shasta M. |last4=Dunning |first4=Stuart A. |last5=Steig |first5=Eric J. |last6=Freeman |first6=Stewart P. H. T. |last7=Stuart |first7=Finlay M. |last8=Winter |first8=Kate |last9=Westoby |first9=Matthew J. |last10=Sugden |first10=David E. |date=3 February 2016 |title=Evidence for the stability of the West Antarctic Ice Sheet divide for 1.4 million years |journal=Nature Communications |volume=7 |page=10325 |doi=10.1038/ncomms10325 |pmid=26838462 |pmc=4742792 |bibcode=2016NatCo...710325H }}</ref> Its collapse would cause ~{{convert|3.3|m|ftin|abbr=on}} of sea level rise.<ref name="Bamber2009">{{cite journal |last1=Bamber |first1=J.L. |last2=Riva |first2=R.E.M. |last3=Vermeersen |first3=B.L.A. |last4=LeBrocq |first4=A.M. |title=Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet |journal=Science |date=14 May 2009 |volume=324 |issue=5929 |pages=901–903 |doi=10.1126/science.1169335 |pmid=19443778 |bibcode=2009Sci...324..901B |s2cid=11083712}}</ref> This collapse is now considered practically inevitable, as it appears to have already occurred during the [[Eemian]] period 125,000 years ago, when temperatures were similar to the early 21st century.<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>{{Cite journal|last1=Turney|first1=Chris S. M.|last2=Fogwill|first2=Christopher J.|last3=Golledge|first3=Nicholas R.|last4=McKay |first4=Nicholas P. |last5=Sebille |first5=Erik van |last6=Jones |first6=Richard T. |last7=Etheridge |first7=David|last8=Rubino |first8=Mauro|last9=Thornton|first9=David P. |last10=Davies|first10=Siwan M.|last11=Ramsey|first11=Christopher Bronk|date=2020-02-11|title=Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica|journal=Proceedings of the National Academy of Sciences |volume=117 |issue=8 |pages=3996–4006 |language=en |doi=10.1073/pnas.1902469117|issn=0027-8424 |pmid=32047039 |pmc=7049167 |bibcode=2020PNAS..117.3996T|doi-access=free}}</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="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><ref>{{Cite web |last=AHMED |first=Issam |title=Antarctic octopus DNA reveals ice sheet collapse closer than thought |url=https://phys.org/news/2023-12-antarctic-octopus-dna-reveals-ice.html |access-date=2023-12-23 |website=phys.org |language=en}}</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>{{cite news |last1=Poynting |first1=Mark |title=Sea-level rise: West Antarctic ice shelf melt 'unavoidable' |url=https://www.bbc.com/news/science-environment-67171231 |access-date=26 October 2023 |agency=BBC |date=24 October 2023}}</ref> This disappearance would take an estimated 2000 years. The absolute minimum for the loss of West Antarctica ice is 500 years, and the potential maximum is 13,000 years.<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}}</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 only way to stopOnce ice loss from the West Antarctica onceis triggered, the only way to restore it to near-present values is by lowering the global temperature to {{convert|1|C-change|F-change}} ''below'' the preindustrial level. This would be {{convert|2|C-change|F-change}} below the temperature of 2020.<ref name="Garbe2020" /> Other researchers suggested that a [[climate engineering]] intervention to stabilize the ice sheet's glaciers may delay its loss by centuries and give more time to adapt. However this is an uncertain proposal, and would end up as one of the most expensive projects ever attempted.<ref name="Wolovick2023a">{{Cite journal |last1=Wolovick |first1=Michael |last2=Moore |first2=John |last3=Keefer |first3=Bowie |date=27 March 2023 |title=Feasibility of ice sheet conservation using seabed anchored curtains |url=https://academic.oup.com/pnasnexus/article/2/4/pgad103/7087219 |journal=PNAS Nexus |volume=2 |issue=3 |pages=pgad053 |language=en |doi=10.1093/pnasnexus/pgad053 |pmid=37007716 |pmc=10062297 }}</ref><ref name="Wolovick2023b">{{Cite journal |last1=Wolovick |first1=Michael |last2=Moore |first2=John |last3=Keefer |first3=Bowie |date=27 March 2023 |title=The potential for stabilizing Amundsen Sea glaciers via underwater curtains |url=https://academic.oup.com/pnasnexus/article/2/4/pgad103/7087219 |journal=PNAS Nexus |volume=2 |issue=4 |pages=pgad103 |language=en |doi=10.1093/pnasnexus/pgad103 |pmid=37091546 |pmc=10118300 }}</ref>
 
====Isostatic rebound====
2021 research indicates that [[isostatic rebound]] after the loss of the main portion of the West Antarctic ice sheet would ultimately add another {{convert|1.02|m|ftin|abbr=on}} to global sea levels. This effect would start to increase sea levels before 2100. However it would take 1000 years for it to cause {{convert|83|cm|ftin|abbr=on}} of sea level rise. At this point, West Antarctica itself would be {{convert|610|m|ftin|abbr=on}} higher than now. Estimates of isostatic rebound after the loss of East Antarctica's subglacial basins suggest increases of between {{convert|8|cm|ftin|abbr=on}} and {{convert|57|cm|ftin|abbr=on}}<ref name="Pan2021" />
 
[[File:Mass changes of the Greenland Ice Sheet between 2002 and 2019.webp|thumb|left|upright=1.4|Trends of Greenland ice loss between 2002 and 2019<ref>{{cite journal |last1=Sasgen |first1=Ingo |last2=Wouters |first2=Bert |last3=Gardner |first3=Alex S. |last4=King |first4=Michalea D. |last5=Tedesco |first5=Marco |last6=Landerer |first6=Felix W. |last7=Dahle |first7=Christoph |last8=Save |first8=Himanshu |last9=Fettweis |first9=Xavier |date=20 August 2020 |title=Return to rapid ice loss in Greenland and record loss in 2019 detected by the GRACE-FO satellites |journal=Communications Earth & Environment |volume=1 |issue=1 |page=8 |doi=10.1038/s43247-020-0010-1 |bibcode=2020ComEE...1....8S |s2cid=221200001 |language=en |issn=2662-4435|doi-access=free }} [[File:CC-BY icon.svg|50px]] Text and images are available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>]]▼
 
=== Greenland ice sheet loss ===
[[File:Greenland ssi 2007.jpg|thumb|upright=1.05|Greenland 2007 melt, measured as the difference between the number of days on which melting occurred in 2007 compared to the average annual melting days from 1988 to 2006<ref>{{cite web|url=https://earthobservatory.nasa.gov/newsroom|title=NASA Earth Observatory - Newsroom|date=18 January 2019|website=earthobservatory.nasa.gov}}</ref>]]
Most ice on Greenland is in the [[Greenland ice sheet]] which is {{Convert|3|km|ft|abbr=on|sigfig=1}} at its thickest. The rest of Greenland ice forms isolated glaciers and ice caps. The average annual ice loss in Greenland more than doubled in the early 21st century compared to the 20th century.<ref>{{cite journal |last1=Kjeldsen |first1=Kristian K. |last2=Korsgaard |first2=Niels J. |last3=Bjørk |first3=Anders A. |last4=Khan |first4=Shfaqat A. |last5=Box |first5=Jason E. |last6=Funder |first6=Svend |last7=Larsen |first7=Nicolaj K. |last8=Bamber |first8=Jonathan L. |last9=Colgan |first9=William |last10=van den Broeke |first10=Michiel |last11=Siggaard-Andersen |first11=Marie-Louise |last12=Nuth |first12=Christopher |last13=Schomacker |first13=Anders |last14=Andresen |first14=Camilla S. |last15=Willerslev |first15=Eske |last16=Kjær |first16=Kurt H. |title=Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900 |journal=Nature |date=16 December 2015 |volume=528 |issue=7582 |pages=396–400 |doi=10.1038/nature16183 |pmid=26672555 |bibcode=2015Natur.528..396K |hdl=10852/50174 |s2cid=4468824 |url=https://research-information.bris.ac.uk/en/publications/spatial-and-temporal-distribution-of-mass-loss-from-the-greenland-ice-sheet-since-ad-1900(29ed76ed-b8f7-4b99-bf59-a275b0a22ce7).html }}</ref> Its contribution to sea level rise correspondingly increased from 0.07&nbsp;mm per year between 1992 and 1997 to 0.68&nbsp;mm per year between 2012 and 2017. Total ice loss from the Greenland ice sheet between 1992 and 2018 amounted to 3,902 gigatons (Gt) of ice. This is equivalent to a SLR contribution of 10.8&nbsp;mm.<ref>{{Cite journal|last1=Shepherd|first1=Andrew|last2=Ivins|first2=Erik|last3=Rignot|first3=Eric|last4=Smith|first4=Ben|last5=van den Broeke|first5=Michiel|last6=Velicogna|first6=Isabella|author-link6=Isabella Velicogna|last7=Whitehouse|first7=Pippa|last8=Briggs|first8=Kate|last9=Joughin|first9=Ian|last10=Krinner|first10=Gerhard|last11=Nowicki|first11=Sophie|date=2020-03-12|title=Mass balance of the Greenland Ice Sheet from 1992 to 2018|journal=Nature|language=en|volume=579|issue=7798|pages=233–239|doi=10.1038/s41586-019-1855-2|pmid=31822019|hdl=2268/242139|s2cid=219146922|issn=1476-4687|url=https://orbi.uliege.be/handle/2268/242139}}</ref> The contribution for the 2012–2016 period was equivalent to 37% of sea level rise from ''land ice'' sources (excluding thermal expansion).<ref name="Bamber2018">{{cite journal |last1=Bamber |first1=Jonathan L |last2=Westaway |first2=Richard M |last3=Marzeion |first3=Ben |last4=Wouters |first4=Bert |title=The land ice contribution to sea level during the satellite era |journal=Environmental Research Letters |date=1 June 2018 |volume=13 |issue=6 |page=063008 |doi=10.1088/1748-9326/aac2f0 |bibcode=2018ERL....13f3008B |doi-access=free }}</ref> This observed rate of ice sheet melting is at the higher end of predictions from past [[IPCC]] assessment reports.<ref>{{Cite web|url=https://news.uci.edu/2019/12/19/greenland-ice-loss-is-at-worse-case-scenario-levels-study-finds/|title=Greenland ice loss is at 'worse-case scenario' levels, study finds|date=2019-12-19|website=UCI News|language=en-US|access-date=2019-12-28}}</ref><ref name="Slater-2020"/>
[[File:Beckmann 2023 Greenland 2300 RCP85 extent.png|thumb|left|2023 projections of how much the Greenland ice sheet may shrink from its present extent by the year 2300 under the worst possible climate change scenario (upper half) and of how much faster its remaining ice will be flowing in that case (lower half)<ref name="Beckmann2023">{{Cite journal |last1=Beckmann |first1=Johanna |last2=Winkelmann |first2=Ricarda |date=27 July 2023 |title=Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet |journal=The Cryosphere |language=en |volume=17 |issue=7 |pages=3083–3099 |doi=10.5194/tc-17-3083-2023 |bibcode=2023TCry...17.3083B |doi-access=free }}</ref>]]
 
In 2021, [[AR6]] estimated that by 2100, the melting of Greenland ice sheet would most likely add around {{cvt|6|cm|in|frac=2}} to sea levels under the low-emission scenario, and {{cvt|13|cm|in|frac=2}} under the high-emission scenario. The first scenario, [[Shared Socioeconomic Pathways|SSP1-2.6]], largely fulfils the [[Paris Agreement]] goals, while the other, SSP5-8.5, has the emissions accelerate throughout the century. The uncertainty about [[ice sheet dynamics]] can affect both pathways. In the best-case scenario, ice sheet under SSP1-2.6 gains enough mass by 2100 through [[surface mass balance]] feedbacks to reduce the sea levels by {{cvt|2|cm|in|frac=2}}. In the worst case, it adds {{cvt|15|cm|in|frac=2}}. For SSP5-8.5, the best-case scenario is adding {{cvt|5|cm|in|frac=2}} to sea levels, and the worst-case is adding {{cvt|23|cm|in|frac=2}}.<ref name="IPCC AR6 WG1 Ch.9" />{{Rp|page=1260}}
 
▲[[File:Mass changes of the Greenland Ice Sheet between 2002 and 2019.webp|thumb|left|upright=1.4|Trends of Greenland ice loss between 2002 and 2019<ref>{{cite journal |last1=Sasgen |first1=Ingo |last2=Wouters |first2=Bert |last3=Gardner |first3=Alex S. |last4=King |first4=Michalea D. |last5=Tedesco |first5=Marco |last6=Landerer |first6=Felix W. |last7=Dahle |first7=Christoph |last8=Save |first8=Himanshu |last9=Fettweis |first9=Xavier |date=20 August 2020 |title=Return to rapid ice loss in Greenland and record loss in 2019 detected by the GRACE-FO satellites |journal=Communications Earth & Environment |volume=1 |issue=1 |page=8 |doi=10.1038/s43247-020-0010-1 |bibcode=2020ComEE...1....8S |s2cid=221200001 |language=en |issn=2662-4435|doi-access=free }} [[File:CC-BY icon.svg|50px]] Text and images are available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>]]
Greenland's peripheral glaciers and ice caps crossed an irreversible tipping point around 1997. Sea level rise from their loss is now unstoppable.<ref>{{cite journal |last1=Noël |first1=B. |last2=van de Berg |first2=W. J |last3=Lhermitte |first3=S. |last4=Wouters |first4=B. |last5=Machguth |first5=H. |last6=Howat |first6=I. |last7=Citterio |first7=M. |last8=Moholdt |first8=G. |last9=Lenaerts |first9=J. T. M. |last10=van den Broeke |first10=M. R. |title=A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps |journal=Nature Communications |date=31 March 2017 |volume=8 |issue=1 |page=14730 |doi=10.1038/ncomms14730 |pmid=28361871 |pmc=5380968 |bibcode=2017NatCo...814730N }}</ref><ref>{{cite news |title=Warming Greenland ice sheet passes point of no return|url=https://news.osu.edu/warming-greenland-ice-sheet-passes-point-of-no-return/|date=13 August 2020|access-date=15 August 2020 |work=Ohio State University}}</ref><ref>{{cite journal|last1=King|first1=Michalea D.|last2=Howat|first2=Ian M.|last3=Candela|first3=Salvatore G.|last4=Noh|first4=Myoung J.|last5=Jeong|first5=Seongsu|last6=Noël|first6=Brice P. Y.|last7=van den Broeke|first7=Michiel R.|last8=Wouters|first8=Bert|last9=Negrete|first9=Adelaide|date=13 August 2020|title=Dynamic ice loss from the Greenland Ice Sheet driven by sustained glacier retreat|journal=Communications Earth & Environment|language=en|volume=1|issue=1|pages=1–7|doi=10.1038/s43247-020-0001-2|bibcode=2020ComEE...1....1K |issn=2662-4435|doi-access=free}} [[File:CC-BY icon.svg|50x50px]] Text and images are available under a [[creativecommons:by/4.0/|Creative Commons Attribution 4.0 International License]].</ref> However the temperature changes in future, the warming of 2000–2019 had already damaged the ice sheet enough for it to eventually lose ~3.3% of its volume. This is leading to {{cvt|27|cm|in|frac=2}} of future sea level rise.<ref>{{cite journal |last1=Box |first1=Jason E. |last2=Hubbard |first2=Alun |last3=Bahr |first3=David B. |last4=Colgan |first4=William T. |last5=Fettweis |first5=Xavier |last6=Mankoff |first6=Kenneth D. |last7=Wehrlé |first7=Adrien |last8=Noël |first8=Brice |last9=van den Broeke |first9=Michiel R. |last10=Wouters |first10=Bert |last11=Bjørk |first11=Anders A. |last12=Fausto |first12=Robert S. |title=Greenland ice sheet climate disequilibrium and committed sea-level rise |url=https://www.nature.com/articles/s41558-022-01441-2 |journal=Nature Climate Change |date=29 August 2022 |volume=12 |issue=9 |pages=808–813 |doi=10.1038/s41558-022-01441-2 |bibcode=2022NatCC..12..808B |s2cid=251912711 }}</ref> At a certain level of global warming, the Greenland ice sheet will almost completely melt. Ice cores show this happened at least once during the last million years, when the temperatures have at most been {{convert|2.5|C-change|F-change}} warmer than the preindustrial.<ref>{{Cite journal|last1=Irvalı|first1=Nil|last2=Galaasen|first2=Eirik V.|last3=Ninnemann|first3=Ulysses S.|last4=Rosenthal|first4=Yair|last5=Born|first5=Andreas|last6=Kleiven|first6=Helga (Kikki) F.|date=18 December 2019 |title=A low climate threshold for south Greenland Ice Sheet demise during the Late Pleistocene|journal=Proceedings of the National Academy of Sciences|volume=117|issue=1|pages=190–195|language=en|doi=10.1073/pnas.1911902116|issn=0027-8424|pmid=31871153|pmc=6955352|doi-access=free}}</ref><ref name="Christ2021">{{cite journal |last1=Christ |first1=Andrew J. |last2=Bierman |first2=Paul R. |last3=Schaefer |first3=Joerg M.|last4=Dahl-Jensen |first4=Dorthe |last5=Steffensen |first5=Jørgen P. |last6=Corbett |first6=Lee B. |last7=Peteet |first7=Dorothy M. |last8=Thomas |first8=Elizabeth K. |last9=Steig |first9=Eric J. |last10=Rittenour |first10=Tammy M. |last11=Tison |first11=Jean-Louis |last12=Blard |first12=Pierre-Henri |last13=Perdrial |first13=Nicolas |last14=Dethier |first14=David P. |last15=Lini |first15=Andrea |last16=Hidy |first16=Alan J. |last17=Caffee |first17=Marc W. |last18=Southon |first18=John |title=A multimillion-year-old record of Greenland vegetation and glacial history preserved in sediment beneath 1.4 km of ice at Camp Century |journal=Proceedings of the National Academy of Sciences of the United States|date=30 March 2021 |volume=118 |issue=13 |pages=e2021442118 |doi=10.1073/pnas.2021442118 |pmid=33723012 |pmc=8020747 |bibcode=2021PNAS..11821442C |doi-access=free }}</ref>
 
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{{further|Climate change in Asia#Sea level rise}}
[[File:20091011松川浦まつかわうら.jpg|thumb|upright=1.3|Matsukawaura [[Lagoon]], located in [[Fukushima Prefecture]] of Honshu Island]]
[[File:Urban-Rural Population and Land Area Estimates, v2, 2010 Bangladesh (13873798283).jpg|thumb|upright=31.35|2010 estimates of population exposure to sea level rise in Bangladesh]]
Asia has the largest population at risk from sea level due to its dense coastal populations. As of 2022, some 63 million people in [[East Asia|East]] and [[South Asia]] were already at risk from a [[100-year flood]]. This is largely due to inadequate coastal protection in many countries. [[Bangladesh]], [[China]], [[India]], [[Indonesia]], [[Japan]], [[Pakistan]], the [[Philippines]], [[Thailand]] and [[Vietnam]] alone account for 70% of people exposed to sea level rise during the 21st century.<ref name="AR6_WGII_Chapter10" /><ref>{{Cite journal|last=McLeman|first=Robert|date=2018|title=Migration and displacement risks due to mean sea-level rise|journal=Bulletin of the Atomic Scientists|volume=74|issue=3|pages=148–154|doi=10.1080/00963402.2018.1461951|issn=0096-3402|bibcode=2018BuAtS..74c.148M|s2cid=150179939}}</ref> [[Climate change in Bangladesh|Sea level rise in Bangladesh]] is likely to displace 0.9-2.1&nbsp;million people by 2050. It may also force the relocation of up to one third of power plants as early as 2030, and many of the remaining plants would have to deal with the increased salinity of their cooling water.<ref name="AR6_WGII_Chapter10" /><ref name="DeLellis2021">{{cite journal |last1=De Lellis |first1=Pietro |last2=Marín |first2=Manuel Ruiz |last3=Porfiri |first3=Maurizio |date=29 March 2021 |title=Modeling Human Migration Under Environmental Change: A Case Study of the Effect of Sea Level Rise in Bangladesh |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020EF001931 |journal=Earth's Future |volume=9 |issue=4 |pages=e2020EF001931 |doi=10.1029/2020EF001931 |bibcode=2021EaFut...901931D |hdl=10317/13078 |s2cid=233626963 }}</ref> Nations like Bangladesh, Vietnam and China with extensive rice production on the coast are already seeing adverse impacts from saltwater intrusion.<ref>{{Cite web|url=http://www.fao.org/nr/climpag/pub/EIre0047_en.asp|title=Potential Impacts of Sea-Level Rise on Populations and Agriculture|website=www.fao.org|access-date=2018-10-21|archive-date=2020-04-18|archive-url=https://web.archive.org/web/20200418035608/http://www.fao.org/nr/climpag/pub/eire0047_en.asp}}</ref>
 
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=== North America ===
[[File:October 17 2016 sunny day tidal flooding at Brickell Bay Drive and 12 Street downtown Miami, 4.34 MLLW high tide am.jpg|thumb|[[Tidal flooding]] in [[Climate of Miami|Miami]] during a [[king tide]] (October 17, 2016). The risk of tidal flooding increases with sea level rise.]]
As of 2017, around 95 million Americans lived on the coast. The figures for [[Canada]] and [[Mexico]] were 6.5 million and 19 million. Increased chronic [[nuisance flooding]] and [[king tide]] flooding is already a problem in the highly [[Climate change vulnerability|vulnerable]] state of [[Florida]].<ref>{{Cite web|date=2020-02-10|title=Florida Coastal Flooding Maps: Residents Deny Predicted Risks to Their Property|url=https://www.ecowatch.com/florida-coastal-flooding-maps-2645087745.html|access-date=2021-01-31|website=EcoWatch|language=en}}</ref> The [[US East Coast]] is also vulnerable.<ref>{{cite journal|last1=Sweet & Park |title=Increased nuisance flooding along the coasts of the United States due to sea level rise: Past and future |journal=Geophysical Research Letters |year=2015 |volume=42 |issue=22 |pages=9846–9852 |doi=10.1002/2015GL066072 |bibcode=2015GeoRL..42.9846M |s2cid=19624347}}</ref> On average, the number of days with [[tidal flooding]] in the US increased 2 times in the years 2000–2020, reaching 3–7 days per year. In some areas the increase was much stronger: 4 times in the Southeast Atlantic and 11 times in the Western Gulf. By the year 2030 the average number is expected to be 7–15 days, reaching 25–75 days by 2050.<ref>{{cite web |title=High Tide Flooding |url=https://coast.noaa.gov/states/fast-facts/recurrent-tidal-flooding.html |website=NOAA |access-date=10 July 2023}}</ref> U.S. coastal cities have responded with [[beach nourishment]] or ''beach replenishment.'' This trucks in mined sand in addition to other adaptation measures such as zoning, restrictions on state funding, and building code standards.<ref name="ClimateCentral2012">{{cite web|url=http://www.climatecentral.org/news/its-beach-season-enjoy-it-while-you-can|title=Climate Change, Sea Level Rise Spurring Beach Erosion|year=2012|website=Climate Central}}</ref><ref>{{Cite journal|last=Carpenter|first=Adam T.|date=2020-05-04|title=Public priorities on locally-driven sea level rise planning on the East Coast of the United States|journal=PeerJ|language=en|volume=8|pages=e9044|doi=10.7717/peerj.9044|pmid=32411525|pmc=7204830|issn=2167-8359 |doi-access=free }}</ref>

Along an estimated some ~15% of the US coastline, the majority of local [[groundwater]] levels are already below sea level. This places those groundwater reservoirs at risk of sea water intrusion. That would render fresh water unusable once its concentration exceeds 2-3%.<ref>{{cite journal |last1=Jasechko |first1=Scott J.|last2=Perrone |first2=Debra |last3=Seybold |first3=Hansjörg |last4=Fan |first4=Ying |last5=Kirchner |first5=James W. |title=Groundwater level observations in 250,000 coastal US wells reveal scope of potential seawater intrusion |date=26 June 2020 |journal=Nature Communications |volume=11 |issue=1 |page=3229 |doi=10.1038/s41467-020-17038-2 |pmid=32591535 |pmc=7319989 |bibcode=2020NatCo..11.3229J }}</ref> Damage is also widespread in Canada. It will affect major cities like [[Halifax, Nova Scotia|Halifax]] and more remote locations like [[Lennox Island (Prince Edward Island)|Lennox Island]]. The [[Mi'kmaq]] [[Lennox Island First Nation|community]] there is already considering relocation due to widespread coastal erosion. In Mexico, damage from SLR to [[tourism]] hotspots like [[Cancun]], [[Isla Mujeres]], [[Playa del Carmen]], [[Puerto Morelos]] and [[Cozumel]] could amount to US$1.4–2.3&nbsp;billion.<ref name="AR6_WGII_Chapter14" /> The increase in [[storm surge]] due to sea level rise is also a problem. Due to this effect [[Hurricane Sandy]] caused an additional US$8 billion in damage, impacted 36,000 more houses and 71,000 more people.<ref>{{cite journal |title=Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change |journal=Nature Communications |date=18 May 2021 |volume=12 |bibcode=2021NatCo..12.2720S |last1=Strauss |first1=Benjamin H. |last2=Orton |first2=Philip M. |last3=Bittermann |first3=Klaus |last4=Buchanan |first4=Maya K. |last5=Gilford |first5=Daniel M. |last6=Kopp |first6=Robert E. |last7=Kulp |first7=Scott |last8=Massey |first8=Chris |last9=Moel |first9=Hans de |last10=Vinogradov |first10=Sergey |issue=1 |page=2720 |doi=10.1038/s41467-021-22838-1 |pmid=34006886 |pmc=8131618 |s2cid=234783225 }}</ref><ref>{{cite news |last1=Seabrook |first1=Victoria |title=Climate change to blame for $8 billion of Hurricane Sandy losses, study finds |url=https://news.sky.com/story/climate-change-to-blame-for-8-billion-of-hurricane-sandy-losses-study-finds-12309974#:~:text=The%20raised%20water%20levels%20allowed,36%2C000%20homes%20and%2071%2C000%20people. |access-date=9 July 2023 |agency=Sky News |publisher=Nature Communications |date=19 May 2021}}</ref> In the future, the northern [[Gulf of Mexico]], [[Atlantic Canada]] and the [[Pacific coast of Mexico]] would experience the greatest sea level rise. By 2030, flooding along the US [[Gulf Coast]] could cause economic losses of up to US$176&nbsp;billion. Using [[nature-based solutions]] like [[wetland restoration]] and [[oyster reef]] restoration could avoid around US$50 billion of this.<ref name="AR6_WGII_Chapter14" />
 
▲[[File:2050 Projected sea level rise - United States coasts - NOAA.svg|thumb|upright=1.35|left|[[NOAA]] predicts different levels of sea level rise through 2050 for several US coastlines.<ref name=NOAA-2022 />|alt=A comparison of SLR in six parts of the US. The Gulf Coast and East Coast see the most SLR, whereas the West Coast the least]]
 
By 2050, coastal flooding in the US is likely to rise tenfold to four "moderate" flooding events per year. That forecast is even without storms or heavy rainfall.<ref>{{cite web |title=U.S Coastline to See Up to a Foot of Sea Level by 2050 |url=https://www.noaa.gov/news-release/us-coastline-to-see-up-to-foot-of-sea-level-rise-by-2050 |access-date=February 16, 2022 |website=National Oceanic and Atmospheric Administration|date=15 February 2022 }}</ref><ref>{{cite web |date=2022 |title=More Damaging Flooding, 2022 Sea Level Rise Technical Report |url=https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-tech-report.html#step2 |access-date=2022-03-18 |website=National Ocean Service, [[NOAA]]}}</ref> In [[New York City]], current [[100-year flood]] would occur once in 19–68 years by 2050 and 4–60 years by 2080.<ref>{{cite web|last=Gornitz|first=Vivien|date=2002|title=Impact of Sea Level Rise in the New York City Metropolitan Area|url=https://eportfolios.macaulay.cuny.edu/bird2012/files/2012/07/Impacts-of-SLR-in-the-NYC-Metropolitan-Area.-pdf.pdf|access-date=2020-08-09|website=Global and Planetary Change|archive-date=2019-09-26|archive-url=https://web.archive.org/web/20190926115312/https://eportfolios.macaulay.cuny.edu/bird2012/files/2012/07/Impacts-of-SLR-in-the-NYC-Metropolitan-Area.-pdf.pdf|url-status=dead}}</ref> By 2050, 20&nbsp;million people in the greater [[New York City]] area would be at risk. This is because 40% of existing [[water treatment]] facilities would be compromised and 60% of [[power plant]]s will need relocation.
 
In future, the northern [[Gulf of Mexico]], [[Atlantic Canada]] and the [[Pacific coast of Mexico]] would experience the greatest sea level rise. By 2030, flooding along the US [[Gulf Coast]] could cause economic losses of up to US$176&nbsp;billion. Using [[nature-based solutions]] like [[wetland restoration]] and [[oyster reef]] restoration could avoid around US$50 billion of this.<ref name="AR6_WGII_Chapter14" /> By 2050, coastal flooding in the US is likely to rise tenfold to four "moderate" flooding events per year. That forecast is even without storms or heavy rainfall.<ref>{{cite web |title=U.S Coastline to See Up to a Foot of Sea Level by 2050 |url=https://www.noaa.gov/news-release/us-coastline-to-see-up-to-foot-of-sea-level-rise-by-2050 |access-date=February 16, 2022 |website=National Oceanic and Atmospheric Administration|date=15 February 2022 }}</ref><ref>{{cite web |date=2022 |title=More Damaging Flooding, 2022 Sea Level Rise Technical Report |url=https://oceanservice.noaa.gov/hazards/sealevelrise/sealevelrise-tech-report.html#step2 |access-date=2022-03-18 |website=National Ocean Service, [[NOAA]]}}</ref> In [[New York City]], current [[100-year flood]] would occur once in 19–68 years by 2050 and 4–60 years by 2080.<ref>{{cite web|last=Gornitz|first=Vivien|date=2002|title=Impact of Sea Level Rise in the New York City Metropolitan Area|url=https://eportfolios.macaulay.cuny.edu/bird2012/files/2012/07/Impacts-of-SLR-in-the-NYC-Metropolitan-Area.-pdf.pdf|access-date=2020-08-09|website=Global and Planetary Change|archive-date=2019-09-26|archive-url=https://web.archive.org/web/20190926115312/https://eportfolios.macaulay.cuny.edu/bird2012/files/2012/07/Impacts-of-SLR-in-the-NYC-Metropolitan-Area.-pdf.pdf|url-status=dead}}</ref> By 2050, 20&nbsp;million people in the greater [[New York City]] area would be at risk. This is because 40% of existing [[water treatment]] facilities would be compromised and 60% of [[power plant]]s will need relocation. By 2100, sea level rise of {{cvt|0.9|m|ft|frac=2}} and {{cvt|1.8|m|ft|frac=2}} would threaten 4.2 and 13.1&nbsp;million people in the US, respectively. In [[California]] alone, {{cvt|2|m|ft|frac=2}} of SLR could affect 600,000 people and threaten over US$150&nbsp;billion in property with inundation. This potentially represents over 6% of the state's [[GDP]]. In [[North Carolina]], a meter of SLR inundates 42% of the [[Albemarle-Pamlico Peninsula]], costing up to US$14&nbsp;billion. In nine southeast US states, the same level of sea level rise would claim up to 13,000 historical and archaeological sites, including over 1000 sites eligible for inclusion in the [[National Register for Historic Places]].<ref name="AR6_WGII_Chapter14">Hicke, J.A., S. Lucatello, L.D., Mortsch, J. Dawson, M. Domínguez Aguilar, C.A.F. Enquist, E.A. Gilmore, D.S. Gutzler, S. Harper, K. Holsman, E.B. Jewett, T.A. Kohler, and KA. Miller, 2022: [https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Chapter14.pdf Chapter 14: North America]. In [https://www.ipcc.ch/report/ar6/wg2/ Climate Change 2022: Impacts, Adaptation and Vulnerability] [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, US, pp. 1929–2042</ref>
 
=== Island nations ===
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