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{{Short description|Antarctic glacier}}
{{Infobox glacier
| child =
| name = Thwaites Glacier
| other_name = "Doomsday Glacier"
| photo = ThwaitsThwaites Glacier.jpg
| photo_width =
| photo_alt = Thwaites Glacier
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'''Thwaites Glacier''' is an unusually broad and vast [[Antarctic]] [[glacier]] located east of [[Mount Murphy]], on the [[Walgreen Coast]] of [[Marie Byrd Land]]. It was initially sighted by polar researchers in 1940, mapped in 1959–1966 and officially named in 1967, after the late American [[glaciologist]] Fredrik T. Thwaites.<ref name="ThwaitesFacts" /><ref name="gnisThwaitesGlacier" /> ThisThe glacier flows into [[Pine Island Bay]], part of the [[Amundsen Sea]], at surface speeds which exceed {{convert|2|km}} per year near its [[grounding line]]. Its fastest-flowing grounded ice is centered between {{convert|50 and 100|km}} east of Mount Murphy.<ref name="ThwaitesFacts" /> TheLike changemany thatother areparts currentlyof occurringthe at[[cryosphere]], thisit glacierhas isbeen adversely affected by [[climate change]], and provides one exampleof the more notable examples of the [[retreat of glaciers since 1850]].
 
Thwaites Glacier is closely monitored for its potential to [[Sea level rise|elevate sea levels]].<ref>{{cite magazine|url=https://www.wired.com/story/antarctica-thwaites-glacier-breaking-point |title=The Race to Understand Antarctica's Most Terrifying Glacier |author=Jon Gertner |date=10 December 2018 |magazine=Wired |access-date=15 December 2018}}</ref> Since the 1980s, Thwaites and [[Pine Island Glacier]] have been described as part of the "weak underbelly" of the [[West Antarctic Ice Sheet]], in part because they seem vulnerable to irreversible retreat and collapse even under relatively little warming, yet also because if they go, the entire ice sheet is likely to eventually follow.<ref name="VoosenSciMag" /><ref name="Hughes1981" /><ref name="Feldmann2015" /> This hypothesis is based on both theoretical studies of the stability of marine ice sheets and observations of large changes on these two glaciers. In recent years, the flow of both of these glaciers has accelerated, their surfaces have lowered, and their grounding lines have retreated.<ref name="NASAUnderbelly" /> They are believed very likely to eventually collapse even without any further warming.<ref name="Joughin2014" /><ref name="Wolovick2018" /><ref name="Holland2023" /> The outsized danger Thwaites poses has led to some reporters nicknaming it the '''Doomsday Glacier''',<ref name="GoodellRS" /><ref name="RowlattBBC" /><ref name="PappasLiveSci" /><ref name="BakerSciAm" /><ref name="FritzCNN" /> although this nickname is controversial among scientists.<ref name="RyanCNET" />
 
The [[Thwaites Ice Shelf]], a floating ice shelf which braces and restrains the eastern portion of Thwaites Glacier, is likely to collapse within a decade from 2021.<ref name="VoosenSciMag" /><ref name="CIRES" /><ref name="AmosBBC">{{Cite news|last=Amos|first=Jonathan|date=13 December 2021 |title=Thwaites: Antarctic glacier heading for dramatic change|language=en-GB|work=BBC News|url=https://www.bbc.com/news/science-environment-59644494|access-date=16 December 2021}}</ref><ref name="KaplanWaPo" /> The glacier's outflow is likely to accelerate substantially after the shelf's disappearance; while the outflow currently accounts for 4% of global [[sea level rise]], it would becomequickly equivalent toreach 5% in the short term, before accelerating further. The amount of ice from Thwaites likely to be lost in this century will only amount to several cmcentimetres of sea level rise,<ref name="ThwaitesFacts" /><ref name="Yu2018" /> but its breakdown will rapidly accelerate in the 22nd and 23rd centuries,<ref name="Wolovick2018" /> and the volume of ice contained in the entire glacier iscan sufficientultimately for an ultimate sea level rise ofcontribute {{cvt|65|cm|frac=2}} to global sea level rise,<ref name="VoosenSciMag">{{Cite web |last1=Voosen |first1=Paul |date=13 December 2021 |title=Ice shelf holding back keystone Antarctic glacier within years of failure|url=https://www.science.org/content/article/ice-shelf-holding-back-keystone-antarctic-glacier-within-years-failure|access-date=22 October 2022|website=[[Science Magazine]]|language=en|quote=Because Thwaites sits below sea level on ground that dips away from the coast, the warm water is likely to melt its way inland, beneath the glacier itself, freeing its underbelly from bedrock. A collapse of the entire glacier, which some researchers think is only centuries away, would raise global sea level by 65 centimeters.}}</ref> which is more than twice the total sea level rise to date.<ref name="SROCC_SPM_20190925IPCC_2021_WGI" /> Some researchers have proposed engineering interventions to stabilize the glacier,<ref name="Wolovick2018" /><ref name="Wolovick2023a" /><ref name="Wolovick2023b" /> but they are very new, costly and their success uncertain.<ref name="Moon2018" />
 
==Location and features==
[[File:Thwaites_Ice_Tongue_from_Sentinel-2_pillars.jpg|thumb|Photo taken in 2019 by the [[Sentinel-2]] satellite of the [[European Space Agency]]. It shows the glacier, the ice shelf on its eastern side, and the remains of the ice tongue in the west, now reduced to a "mélange" of icebergs which is much less effective at supporting the glacier and preventing calving events.<ref name="ESA2023" />]]
[[File:Miles_2020_Thwaites_tongue_shelf.png|thumb|Thwaites Ice Shelf and Thwaites Ice Tongue in 2013, soon after the former was formed due to the Thwaites Glacier Tongue breaking up.<ref name="Miles2020" />]]
Thwaites Glacier is located at the northern edge of the [[West Antarctic Ice Sheet]], next to [[Pine Island Glacier]]. Both glaciers continually shed ice from their [[grounding line]] into Pine Island Bay, which is part of the [[Amundsen Sea]]. The fastest flows of ice occur between {{convert|50 and 100|km}} east of Mount Murphy, where they can exceed {{convert|2|km}} per year.<ref name="ThwaitesFacts" /> At {{cvt|120|km}} in width,<ref name="Gramling" /> Thwaites Glacier is the single widest glacier in the world, and it has an area of {{cvt|192,000|sqkm|sqmi|abbr=off}}. This makes it larger than the American state of [[Florida]] ({{cvt|170,000|sqkm|sqmi|abbr=off}}), and a little smaller than the entire island of [[Great Britain]] ({{convert|209,000|sqkm|sqmi|abbr=off}}). It is also very tall, with ice thickness from bedrock to surface measuring between {{convert|800|m|ft|frac=2}} and {{convert|1200|m|ft|frac=2}}.<ref name="ThwaitesFacts">{{cite web |title=Thwaites Glacier Facts |publisher=The International Thwaites Glacier Collaboration |url=https://thwaitesglacier.org/about/facts |access-date=8 July 2023 }}</ref> ThisDue to this immense size, meansenormous mass is shed thatwhen the repeated [[ice calving]] events occur at the glacier's marine terminus – the point where grounding line is in contact with water. –The alsolargest shedevents, enormouson massthe everyglacier's time.more Thevulnerable largestwestern eventsside, are [[seismology|seismically detectable]] at ranges up to {{cvt|1,600|km}}.<ref>{{cite journal | last1= Winberry | first1=J. P. | first2=A. D. | last2=Huerta | first3=S.| last3= Anandakrishnan| first4= R. | last4=Aster | first5=A. | last5=Nyblade | first6= D. A. | last6= Wiens |display-authors= 3| year= 2020 | title= Glacial Earthquakes and Precursory Seismicity Associated with Thwaites‐Glacier Calving | journal= Geophysical Research Letters | volume=47 | issue=3 |doi=10.1029/2019gl086178| bibcode=2020GeoRL..4786178W | s2cid=212851050 | doi-access=free }}</ref>
 
The third Antarctic expedition of [[Richard E. Byrd]] in 1940 is believed to be first official sighting of the coastline of Thwaites. Detailed mapping of the glacier's surface took place between 1959 and 1966.<ref name="ThwaitesFacts" /> In 1967, it was officially named by the [[Advisory Committee on Antarctic Names]] after Fredrik T. Thwaites (1883–1961), who had never personally visited the glacier, but was a renowned [[Glaciology|glacial geologist]], [[Geomorphology|geomorphologist]] and [[professor emeritus]] at the [[University of Wisconsin–Madison]].<ref name="gnisThwaitesGlacier">{{cite web |title = Thwaites Glacier |work=[[Geographic Names Information System]] |publisher=[[United States Geological Survey]] |url={{gnis3|type=antarid|15283}} |access-date = 23 October 2011
Line 40 ⟶ 41:
|publisher=[[United States Geological Survey]] |url={{gnis3|type=antarid|15284}} |access-date=23 October 2011 }}</ref> [[McMurdo Station]] is used by researchers studying the glacier, such as the International Thwaites Glacier Collaboration (ITGC).<ref name="KaplanWaPo" />
 
{{anchor|Thwaites Glacier Tongue}}
===Thwaites Glacier Tongue and Thwaites Iceberg Tongue===
[[File:Miles_2020_Thwaites_tongue_shelf.png|thumb|Thwaites Eastern Ice Shelf (TEIS) and Thwaites Ice Tongue in 2013, soon after the latter broke up and lost cohesion, leading to much faster retreat rates (red instead of blue). Other labels refer to the ice tongue's grounding line, and northern and southern shear zones where it's in direct contact with the ice shelf.<ref name="Miles2020" />]]
[[File:Amundsen Sea Icebergs.jpg|thumb|The B-22 iceberg broke off from the Thwaites Glacier Tongue on March 15, 2002.]]▼
The Thwaites Glacier Tongue, or Western Glacier Tongue ({{coord|75|0|S|106|50|W|type:glacier}}) was a narrow, floating part of the glacier, located about {{cvt|30|mi}} east of [[Mount Murphy]].<ref name="gnisThwaitesGlacierTongue" /> It was the first part of the glacier to be mapped,<ref name="ThwaitesFacts" /> based on 65,000 aerial photographs collected during [[Operation Highjump]] in 1947. Back then, it was about {{cvt|95|km}} long and {{cvt|60|km}} wide.<ref name="Ferrigno1993" /> By the time updated mapping took place during [[Operation Deepfreeze]] in 1967, the glacier tongue had advanced up to {{cvt|75|km}} further north,<ref name="Ferrigno1993" /> and had also experienced massive [[ice calving]] events which had produced Thwaites Iceberg Tongue ({{coord|74|0|S|108|30|W|type:glacier}}),<ref name="gnisThwaitesIcebergTongue" /> a loose collection of icebergs occupying an area as large as {{convert|150|km}} long and {{convert|35-65|km}} wide at the time.<ref name="Ferrigno1993" /> After breaking off from Thwaites Glacier Tongue, those icebergs ran aground in the Amundsen Sea, about {{cvt|20|mi}} northeast of [[Bear Peninsula]]. Initially, their southern extent was only {{cvt|3|mi}} north of Thwaites Glacier Tongue,<ref name="gnisThwaitesIcebergTongue">{{cite web |title=Thwaites Iceberg Tongue |work=[[Geographic Names Information System]] |publisher=[[United States Geological Survey]] |url={{gnis3|type=antarid|15285}} |access-date=23 October 2011 }}</ref> but as parts of the iceberg tongue continued to calve, it diminished in size (to {{cvt|70|mi}} long and {{cvt|20|mi}} wide.<ref name="gnisThwaitesIcebergTongue" /> By 1986, the entire iceberg tongue had rotated to the side and started to drift away, travelling {{cvt|140|km}} west between 1986 and 1992.<ref name="Ferrigno1993">{{Cite journal |last1=Ferrigno |first1=J.G. |last2=Lucchitta |first2=B.K. |last3=Mullins |first3=K.F. |last4=Allison |first4=A.L. |last5=Allen |first5=R.J. |last6=Gould |first6=W.G. |year=1993 |title=Velocity measurements and changes in position of Thwaites Glacier/iceberg tongue from aerial photography, Landsat images and NOAA AVHRR data |url=https://www.cambridge.org/core/journals/annals-of-glaciology/article/velocity-measurements-and-changes-in-position-of-thwaites-glaciericeberg-tongue-from-aerial-photography-landsat-images-and-noaa-avhrr-data/CD8300D9AD2FB0B7AA0AE5C1B1C6CDCF |journal=Annals of Glaciology |volume=17 |pages=239–244 |language=en |doi=10.3189/S0260305500012908 |bibcode=1993AnGla..17..239F |s2cid=129386351 |doi-access=free }}</ref>
 
====ThwaitesPost-2010 Glacierbreak-up Iceand Tonguecurrent state====
Thwaites Glacier Tongue had also experienced destructive changes, eventually shortening to {{cvt|40|mi}} long and {{cvt|20|mi}} wide.<ref name="gnisThwaitesGlacierTongue" /> By 2012, it went from an [[ice tongue]] firmly attached to the rest of the glacier to a series of icebergs floating next to each other, each no larger than {{convert|1-5|km}} in width and only held in place by [[sea ice]]. The final remainder of the old glacier tongue, with an area of {{convert|470|sqkm}}, disintegrated in 2016. This "melange" of icebergs, nowis still referred to by its old name, as Thwaitesit Glaciercontinues Iceto Tongue,<refoccupy name="SurawyStepney2023"a />substantial stillamount playsof somearea and may retain a stabilizing role,effect buton the glacier. However, future retreat of the surrounding sea ice is likely to trigger disintegration of ever-larger sections, like during the 2019 disintegration of icebergs on its western margin.<ref name="Miles2020">{{Cite journal |last1=Miles |first1=B. W. J. |last2=Stokes |first2=C. R. |last3=Jenkins |first3=A. |last4=Jordan |first4=J. R. |last5=Jamieson |first5=S. S. R. |last6=Gudmundsson |first6=G. H. |date=26 March 2020 |title=Intermittent structural weakening and acceleration of the Thwaites Glacier Tongue between 2000 and 2018 |url=https://www.cambridge.org/core/journals/journal-of-glaciology/article/intermittent-structural-weakening-and-acceleration-of-the-thwaites-glacier-tongue-between-2000-and-2018/2CB70FF6A32B6C4180262DD15088AC0B |journal=Journal of Glaciology |volume=66 |issue=257 |pages=485–495 |language=en |doi=10.1017/jog.2020.20 |bibcode=2020JGlac..66..485M |s2cid=216245431 |doi-access=free |hdl=20.500.11820/82b0834e-a1f4-4c45-b930-d01cce6bcdec |hdl-access=free }}</ref> In 2023, scientists hadfound that ice tongue retreat rates are subject to wide fluctuations after its break-up: over six years of observations, annual retreat accelerated by as much as 40% (from around {{convert|4|km}} to {{convert|6|km}} per year) twice, before slowing back down. These researchers have also repurposed a [[machine learning]] algorithm normally used in [[microbiology]] to identify [[crevasse]]s in Thwaitesthe Glacierremains Iceof Tonguethe ice tongue and project how they may affect its stability.<ref name="SurawyStepney2023">{{Cite journal |last1=Surawy-Stepney |first1=Trystan |last2=Hogg |first2=Anna E. |last3=Cornford |first3=Stephen L. |last4=Davison |first4=Benjamin J. |date=9 January 2023 |title=Episodic dynamic change linked to damage on the Thwaites Glacier Ice Tongue |journal=Nature Geoscience |volume=16 |issue=1 |pages=37–43 |language=en |doi=10.1038/s41561-022-01097-9 |bibcode=2023NatGe..16...37S |s2cid=255669321 }}</ref><ref name="ESA2023">{{cite web |title=AISentinel-1 developedand toAI monitoruncover changesglacier to the globally important Thwaites Glaciercrevasses |datepublisher=9The January[[European 2023Space Agency]] |url=https://physwww.orgesa.int/newsApplications/2023Observing_the_Earth/Copernicus/Sentinel-011/Sentinel-ai-globally-important-thwaites-glacier.html1_and_AI_uncover_glacier_crevasses |publisherdate=[[University9 ofJanuary Leeds]] | website=[[Phys.org]]2023 |access-date=191 JulyAugust 2023 }}</ref>
 
====Iceberg B-22a====
[[File:Miles_2020_ice_tongue.png|thumb|left|B-22A in 2018, next to the remains of the Western Glacier Tongue.]]
On 15 March 2002, the mosta notable calving event took place, when the [[National Ice Center]] reported that an [[iceberg]] named B-22 broke off. This iceberg was about {{cvt|85|km}} long by {{cvt|65|km}} wide, with a total area of some {{cvt|5,490|sqkm}}, comparable to [[Rhode Island]].<ref>{{cite web |url=https://earthobservatory.nasa.gov/images/2310/icebergs-adrift-in-the-amundsen-sea |title=Icebergs Adrift in the Amundsen Sea |date=28 March 2002 |publisher=NASA |access-date=8 July 2023 }}</ref><ref name="BakerSciAm" /> While most of the iceberg broke up quickly, the largest piece, B-22A, with an area of around {{cvt|3000|sqkm|sqmi|frac=2}} or "twice the size of [[Houston, Texas]]", drifted in the vicinity of the glacier even as the rest of the glacier tongue continued to break up. In 2012, it got stuck on seafloor, {{cvt|53|km}} away from the ice tongue, where its presence had some stabilizing impact on the rest of the glacier. In October 2022, it finally started moving again, rapidly drifting to the northwest. It is likely to end up as one of the longest-lived icebergs in history.<ref>{{cite web |url=https://earthobservatory.nasa.gov/images/151202/long-lived-iceberg-sails-away |title=Long-Lived Iceberg Sails Away |date=13 April 2023 |publisher=NASA |access-date=8 July 2023 }}</ref><ref name="BakerSciAm">{{cite web |url=https://www.scientificamerican.com/article/colossal-iceberg-trapped-near-antarcticas-doomsday-glacier-for-20-years-is-finally-on-the-move/ |title=Colossal Iceberg Trapped Near Antarctica's 'Doomsday Glacier' for 20 Years Is Finally on the Move |date=19 April 2023 |website=[[Scientific American]] |publisher=LiveScience |access-date=8 July 2023 }}</ref>
 
===Thwaites Ice Shelf===
[[File:A close look at the shelf (8093672443).jpg|thumb|A close look at the shelf.]]{{Main|Thwaites Ice Shelf}}
Glaciers in Antarctica commonly have [[ice shelf|ice shelves]], which are large bodies of [[sea ice]] that are permanently floating just offshore, and whose presence helps to stabilize the glacier. WhileThough the [[Thwaites Ice Shelf]] has a width of {{cvt|45|km}}<ref name="VoosenSciMag" /> and a vertical thickness of at least {{cvt|587|m}}),<ref name="KorneiEos" /> it is relatively light for its size, and is stabilized by partially resting on an underwater mountain {{cvt|50|km}} offshore.<ref name="Gramling" /> While it only shields the eastern part of the glacier (with the western formerly covered by the Glacier Ice Tongue), itits couldpresence beis veryalready importantsufficient underto counter large calving events on that side of the glacier. Under the hypothesis of [[Marine Ice Cliff Instability|marine ice cliff instability]], whichice suggestscliffs thatat the iceedge shelf'sof failurethe glacier would exposeend up unsustainably tall iceonce cliffsthis atice theshelf edgefails ofand theno glacierlonger andbuttresses them, leadleading to a chain reaction of collapse over centuries.<ref name="CIRES" /><ref name="AmosBBC" /><ref name="NASAUnderbelly" /> However, the accuracy of this hypothesis has been disputed in multiple papers,<ref>{{Cite journal|last1=Clerc|first1=Fiona|last2=Minchew|first2=Brent M.|last3=Behn|first3=Mark D.|year=2019|title=Marine Ice Cliff Instability Mitigated by Slow Removal of Ice Shelves|url=https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GL084183|journal=Geophysical Research Letters|language=en|volume=46|issue=21|pages=12108–12116 |doi=10.1029/2019GL084183|bibcode=2019GeoRL..4612108C |hdl=1912/25343 |s2cid=207781129 |issn=1944-8007|hdl-access=free}}</ref><ref>{{Cite journal|last1=Edwards|first1=Tamsin L.|last2=Brandon|first2=Mark A.|last3=Durand|first3=Gael|last4=Edwards|first4=Neil R.|last5=Golledge|first5=Nicholas R.|last6=Holden|first6=Philip B.|last7=Nias|first7=Isabel J.|last8=Payne|first8=Antony J.|last9=Ritz|first9=Catherine|last10=Wernecke|first10=Andreas |date=6 February 2019|title=Revisiting Antarctic ice loss due to marine ice-cliff instability| display-authors= 3 |url=https://www.nature.com/articles/s41586-019-0901-4|journal=Nature|language=en |volume=566|issue=7742|pages=58–64|doi=10.1038/s41586-019-0901-4|pmid=30728522 |bibcode=2019Natur.566...58E |s2cid=59606547 |issn=1476-4687|hdl=1983/de5e9847-612f-42fb-97b0-5d7ff43d37b8|hdl-access=free}}</ref><ref>{{Cite journal|last1=Golledge|first1=Nicholas R.|last2=Lowry|first2=Daniel P.|date=18 June 2021|title=Is the marine ice cliff hypothesis collapsing?| url=https://www.science.org/doi/10.1126/science.abj3266| journal=Science|volume=372 |issue=6548|pages=1266–1267|doi=10.1126/science.abj3266|pmid=34140372 |bibcode=2021Sci...372.1266G |s2cid=235463129 }}</ref> and some research suggests that the loss of the ice shelf would result in almost no change to glacier's trajectory.<ref name="Gudmundsson2023">{{Cite journal|last1=Gudmundsson |first1=G. H. |last2=Barnes |first2=J. M. A.|last3=Goldberg |first3=D. N. |last4=Morlighem |first4=M. |date=31 May 2023 |title=Limited Impact of Thwaites Ice Shelf on Future Ice Loss From Antarctica |journal=Geophysical Research Letters |language=en|volume=50 |issue=11 |doi=10.1029/2023GL102880 |bibcode=2023GeoRL..5002880G |s2cid=259008792 |doi-access=free }}</ref>
 
===Subglacial features===
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[[Swamp]]-like canal areas and streams underlie the glacier. The upstream swamp canals feed streams, while the dry areas between those streams retard flow of the glacier. Due to this friction, the glacier is considered stable in the short term.<ref name=UTAustin7913>{{cite web|title=Scientists Image Vast Subglacial Water System Underpinning West Antarctica's Thwaites Glacier| url= https://www.utexas.edu/news/2013/07/09/scientists-image-vast-subglacial-water-system-underpinning-west-antarctica%E2%80%99s-thwaites-glacier/|publisher=University of Texas | website= utexas.edu |access-date=9 July 2013 |date=9 July 2013|url-status=dead| archive-url= https://web.archive.org/web/20130715232147/http://www.utexas.edu/news/2013/07/09/scientists-image-vast-subglacial-water-system-underpinning-west-antarctica%E2%80%99s-thwaites-glacier|archive-date=July 15, 2013}}</ref> As warming progresses, these streams expand and form larger structures underneath the glacier.<ref name="Holland2023" /> The largest one to date was discovered by [[NASA]] researchers in 2019 – an underwater cavity formed mostly in the previous three years, nearly {{cvt|350|m|ft|frac=2}} tall and {{cvt|4|km|mi|abbr=off}} wide, with an area two-thirds the size of [[Manhattan]].<ref name="Milillo2019" /><ref name="JacobsNYT">{{cite news|url=https://www.nytimes.com/2019/02/01/climate/thwaites-glacier-antarctica-cavity.html|title=Gigantic Cavity in Antarctica Glacier Is a Product of Rapid Melting, Study Finds|last1=Jacobs|first1=Julia|date=February 1, 2019|work=The New York Times|access-date=4 February 2019}}</ref>
 
In 2014, the area underneath Thwaites Glacier was found to have heat flow from [[geothermal activity]] nearly twice the global average, and about 3.5 times larger in hotspots.<ref name="Schroeder2014">{{cite journal |last1=Schroeder |first1=Dustin M. |last2=Blankenship |first2=Donald D. |last3=Young |first3=Duncan A. |last4=Quartini |first4=Enrica |title=Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet |date=9 June 9, 2014 |journal=Proceedings of the National Academy of Sciences |volume=111 |issue=25 |pages=9070–9072 |doi=10.1073/pnas.1405184111 |pmid=24927578 |pmc=4078843 |bibcode=2014PNAS..111.9070S |doi-access=free}}</ref><ref>{{cite web |title=Researchers find major West Antarctic glacier melting from geothermal sources |date=9 June 2014 |url=https://phys.org/news/2014-06-major-west-antarctic-glacier-geothermal.html |publisher=University of Texas | website=[[Phys.org]] |access-date=13 July 2023 }}</ref> By 2017, scientists have mapped 138 volcanoes beneath the [[West Antarctic Ice Sheet]], with 91 of them previously unknown. [[Marie Byrd Land]], the location of Thwaites and [[Pine Island Glacier]]s, was found to harbor around one volcano per every {{cvt|11,200|sqkm|sqmi|abbr=off}} of area. This density is relatively high, though it is lower than in other global hotspots such as the [[East African Rift]] (one per {{cvt|7,200|sqkm|sqmi|abbr=off}}) or even Antarctica's own central rift (one per {{cvt|7,800|sqkm|sqmi|abbr=off}}). The heat from [[magma]] flows beneath these volcanoes can affect melting,<ref name="Schroeder2014" /><ref>{{cite journal |last1=Damiani |first1=Theresa M. |last2=Jordan |first2=Tom A. |last3=Ferraccioli |first3=Fausto A. |last4=Young |first4=Duncan A. |last5=Blankenship |first5=Donald D. |title=Variable crustal thickness beneath Thwaites Glacier revealed from airborne gravimetry, possible implications for geothermal heat flux in West Antarctica |date=October 10, 2014 |journal=Earth and Planetary Science Letters |volume=407 |pages=109–122 |doi=10.1016/j.epsl.2014.09.023 |bibcode=2014E&PSL.407..109D }}</ref> and the risk of volcano eruptions increases as more ice is lost as a consequence of [[isostatic rebound]].<ref name="VolcanicProvince2018" /> At the same time, both Marie Byrd Land and the central rift also contain the majority of West Antarctica's 29 volcanoes whose height exceeds {{cvt|1|km|mi|abbr=off}}, even as they remain completely covered by ice. This massive size is likely to make them into significant roadblocks to ice flows, and thus gives them the potential to delay glacier retreat in its advanced stages.<ref name="VolcanicProvince2018">{{Cite book |last1=van Wyk de Vries |first1=Maximillian |last2=Bingham |first2=Robert G. |last3=Hein |first3=Andrew S. |date=1 January 2018 |title=Exploration of Subsurface Antarctica: Uncovering Past Changes and Modern Processes |url=https://pubs.geoscienceworld.org/books/book/2098/chapter/114468645/A-new-volcanic-province-an-inventory-of-subglacial |chapter=A new volcanic province: an inventory of subglacial volcanoes in West Antarctica |journalpublisher=The Geological Society, London,of Special PublicationsLondon |volume=461 |pages=231–248 |doi=10.1144/SP461.7 |s2cid=31355701 }}</ref><ref>{{cite news |title=Scientists discover 91 volcanoes below Antarctic ice sheet |url=https://www.theguardian.com/world/2017/aug/12/scientists-discover-91-volcanos-antarctica |access-date=10 February 2020 |work=The Guardian |date=August 12, 2017}}</ref>
 
==Importance==
[[File:Wolovick2023_Thwaites_flows.jpeg|thumb|Overheadright|On viewthis of Thwaites Glaciermap, with arrows marking themark warm water currents, leadingwhich toare itsthe main factor in the projected demise of the Thwaites Glacier.<ref name="Wolovick2023a" />]]
Between 1992 and 2017, Thwaites Glacier retreated at between {{cvt|0.3|km}} and {{cvt|0.8|km}} annually, depending on the sector,<ref name="Milillo2019">{{Cite journal|last1=Milillo |first1=P.|last2=Rignot |first2=E. |last3=Rizzoli |first3=P. |last4=Scheuchl |first4=B.|last5=Mouginot |first5=J. |last6=Bueso-Bello |first6=J. |last7=Prats-Iraola |first7=P. |date=30 January 2019 |title=Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica | url=https://www.science.org/doi/10.1126/science.abj3266| journal=Science Advances |volume=5 |issue=1 |pages=eaau3433 |doi=10.1126/sciadv.aau3433 |pmid=30729155 |pmc=6353628 |bibcode=2019SciA....5.3433M |s2cid=59607481 }}</ref> and experienced a net loss of over 600 billion tons of ice as the result.<ref>{{cite news |last1=Patel |first1=Jugal K. |title=In Antarctica, Two Crucial Glaciers Accelerate Toward the Sea |url=https://www.nytimes.com/interactive/2017/10/26/climate/antarctica-glaciers-melt.html |access-date=4 February 2019 |work=The New York Times |date=26 October 2017}}</ref> This loss had caused about 4% of the global [[sea level rise]] over that period.<ref name="CIRES" /><ref name="JacobsNYT" /> If all of the ice contained within Thwaites Glacier melted (which is expected to take place over multiple centuries),<ref name="VoosenSciMag" /><ref name="Joughin2014" /><ref name="Schwans2023" /> it would be sufficient to raise the global sea level by {{cvt|65|cm|frac=2}}.<ref name="ITGCDrill" /> This is more than twice as large as all of the sea level rise which occurred between 1901 and 2018 (estimated at {{cvt|15|–|25|cm|in|frac=2}}),<ref name="IPCC_2021_WGI" />{{rp|5}} though only a fraction of the total sea level rise which would be seen in the future, particularly under high warming.<ref name="SROCC_SPM_20190925IPCC_2021_WGI">IPCC, 20192021: [https://www.ipcc.ch/sitereport/assetsar6/uploadswg1/sitesdownloads/3report/2022/03/01_SROCC_SPM_FINALIPCC_AR6_WGI_SPM.pdf Summary for Policymakers]. In: [https://www.ipcc.ch/sroccreport/ar6/wg1/ IPCCClimate SpecialChange Report2021: onThe Physical Science Basis. Contribution of Working Group I to the OceanSixth andAssessment CryosphereReport inof athe ChangingIntergovernmental Panel on Climate Change] [H.Masson-ODelmotte, V., PörtnerP. Zhai, DA. Pirani, S.L. Connors, C. RobertsPéan, VS. Masson-DelmotteBerger, PN. ZhaiCaud, Y. Chen, L. Goldfarb, M.I. TignorGomis, EM. PoloczanskaHuang, K. MintenbeckLeitzell, AE. AlegríaLonnoy, MJ.B.R.&nbsp; NicolaiMatthews, AT.K. OkemMaycock, JT. PetzoldWaterfield, BO. RamaYelekçi, NR.M Yu, and B. WeyerZhou (eds.)]. Cambridge University Press, Cambridge, UKUnited Kingdom and New York, NY, US, pp. https://3−32, doi.org/:10.1017/97810091579649781009157896.001.</ref> {{rp|21}}
[[File:Dotto_2022_PIB_meltwater.png|thumb|left|Distribution of meltwater hotspots caused by ice losses in [[Pine Island Bay]], the location of both Thwaites (TEIS refers to Thwaites Eastern Ice Shelf) and Pine Island Glaciers.<ref name="Dotto2022" />]]▼
Fears of the entire [[West Antarctic Ice Sheet]] (WAIS) being prone to geologically rapid (centuries or even decades) collapse in response to accelerated warming from [[greenhouse gas emissions]] have been present since the seminal 1968 paper by [[glaciologist]] J.H. Mercer.<ref name="Mercer1968">{{cite web |last1=Mercer |first1=J. H. |title=ANTARCTIC ICE AND SANGAMON SEA LEVEL |url=https://iahs.info/uploads/dms/079020.pdf |publisher=International Association Of Hydrological Sciences |access-date=8 July 2023 }}</ref><ref name="NASAUnderbelly" /> These concerns were reiterated by Mercer's 1978 follow-up study and by another study in 1973.<ref>{{cite journal |last1=Mercer |first1=J. H. |date=1 January 1978 |title=West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster |journal=Nature |volume=271 |issue=5643 |pages=321–325 |bibcode=1978Natur.271..321M |doi=10.1038/271321a0 |s2cid=4149290}}</ref><ref name="NASAUnderbelly" /> In 1981, scientists also advanced the theory that "the weak underbelly" of the WAIS lay in the [[Amundsen Sea]] region, with the collapse of Thwaites and [[Pine Island Glacier]]s serving as the trigger for the subsequent collapse of the entire ice sheet.<ref name="Hughes1981">{{cite journal | doi-access=free |doi=10.3189/S002214300001159X |title=The weak underbelly of the West Antarctic ice sheet |year=1981 |last1=Hughes |first1=T. J. |journal=Journal of Glaciology |volume=27 |issue=97 |pages=518–525 }}</ref><ref name="NASAUnderbelly">{{cite web |title=The "Unstable" West Antarctic Ice Sheet: A Primer |date=12 May 2014 |publisher=[[NASA]] |url=https://www.nasa.gov/jpl/news/antarctic-ice-sheet-20140512/ |access-date = 8 July 2023 |archive-date=9 July 2023 |archive-url=https://web.archive.org/web/20230709074848/https://www.nasa.gov/jpl/news/antarctic-ice-sheet-20140512/ |url-status=dead }}</ref> This theory was informed by radar measurement data from research flights over West Antarctica in the 1960s and 1970s, which had revealed that in [[Pine Island Bay]], the glacier bed slopes downwards at an angle, and lies well below the [[sea level]]. This [[topography]], in addition to proximity to powerful [[ocean current]]s, makes both glaciers particularly vulnerable to increases in [[ocean heat content]].<ref name="NASAUnderbelly" /><ref name="Dotto2022">{{Cite journal|last1=Dotto |first1=Tiago S. |last2=Heywood |first2=Karen J. |last3=Hall |first3=Rob A. |last4=Scambos |first4=Ted A. |last5=Zheng |first5=Yixi |last6=Nakayama |first6=Yoshihiro |last7=Hyogo |first7=Shuntaro |last8=Snow |first8=Tasha |last9=Wåhlin |first9=Anna K. |last10=Wild |first10=Christian |last11=Truffer |first11=Martin |last12=Muto |first12=Atsuhiro |last13=Alley |first13=Karen E. |last14=Boehme |first14=Lars |last15=Bortolotto |first15=Guilherme A. |last16=Tyler |first16=Scott W. |last17=Pettit |first17=Erin |date=21 December 2022 |title=Ocean variability beneath Thwaites Eastern Ice Shelf driven by the Pine Island Bay Gyre strength| display-authors= 3 |journal=Nature Communications|language=en |volume=13 |issue=1 |page=7840 |doi=10.1038/s41467-022-35499-5 |pmid=36543787 |pmc=9772408 |bibcode=2022NatCo..13.7840D }}</ref> Subsequent research reinforced the hypothesis that Thwaites is the single part of the [[cryosphere]] that would have the largest near-term impact on the sea levels, and that it is likely to disappear even in response to [[climate change]] which had already occurred.<ref>{{cite news|title=This Antarctic glacier is the biggest threat for rising sea levels. The race is on to understand it|url=https://www.washingtonpost.com/news/energy-environment/wp/2016/10/20/u-s-and-u-k-announce-major-research-mission-to-enormous-melting-antarctic-glacier|newspaper=[[The Washington Post]]|date=20 October 2016}}</ref><ref name="Joughin2014" /> Similarly, there is now widespread agreement that its loss is likely to pave the way for the loss of the entire West Antarctic Ice Sheet,<ref name="VoosenSciMag" /><ref name="NASAUnderbelly" /><ref name="Feldmann2015" /> which would raise the sea levels by around {{convert|3.3|ft|m|ft|sigfig=1|abbr=on}} over several centuries or millennia.<ref name="ThwaitesFacts" /><ref name="PappasLiveSci" />▼
 
Once the potential contribution of Thwaites to future sea level rise became better known, some stories have started to refer to it as the "''Doomsday Glacier"''. The first known usage of that nickname was in a May 2017 ''[[Rolling Stone]]'' magazine article by Jeff Goodell,<ref name="GoodellRS">{{cite magazine |first=Jeff |last=Goodell |title=The Doomsday Glacier |date=9 May 2017 |url=https://www.rollingstone.com/politics/politics-features/the-doomsday-glacier-113792/ | magazine=[[Rolling Stone]] |access-date=8 July 2023 }}</ref> and it has subsequently been used more widely.<ref name="RowlattBBC">{{cite web |first=Justin |last=Rowlatt |url=https://www.bbc.com/news/science-environment-51097309 |title=Antarctica melting: Climate change and the journey to the 'doomsday glacier' |publisher=BBC News |date=28 January 2020 }}</ref><ref name="PappasLiveSci" /><ref name="BakerSciAm" /><ref name="FritzCNN" /> While some scientists have embraced the name,<ref>{{Cite journal |last1=Mackintosh |first1=Andrew |date=5 September 2022 |title=Thwaites Glacier and the bed beneath |journal=Nature Geoscience |volume=15 |issue=9 |language=en |pages=687–688 |doi=10.1038/s41561-022-01020-2 |bibcode=2022NatGe..15..687M |s2cid=252081115 }}</ref> many others, including leading researchers like Ted Scambos, [[Eric Rignot]], [[Helen Fricker]] and Robert Larter have criticized it as alarmist and inaccurate.<ref name="RyanCNET">{{cite web |first=Jackson |last=Ryan |url=https://www.cnet.com/science/climate/please-stop-calling-it-the-doomsday-glacier/ |title=Please Stop Calling It the 'Doomsday Glacier' |publisher=[[CNET]] |date=6 September 2022 }}</ref> ▼
▲Fears of the entire [[West Antarctic Ice Sheet]] (WAIS) being prone to geologically rapid (centuries or even decades) collapse in response to accelerated warming from [[greenhouse gas emissions]] have been present since the seminal 1968 paper by [[glaciologist]] J.H. Mercer.<ref name="Mercer1968">{{cite web |last1=Mercer |first1=J. H. |title=ANTARCTIC ICE AND SANGAMON SEA LEVEL |url=https://iahs.info/uploads/dms/079020.pdf |publisher=International Association Of Hydrological Sciences |access-date=8 July 2023 }}</ref><ref name="NASAUnderbelly" /> These concerns were reiterated by Mercer's 1978 follow-up study and by another study in 1973.<ref>{{cite journal |last1=Mercer |first1=J. H. |date=1 January 1978 |title=West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster |journal=Nature |volume=271 |issue=5643 |pages=321–325 |bibcode=1978Natur.271..321M |doi=10.1038/271321a0 |s2cid=4149290}}</ref><ref name="NASAUnderbelly" /> In 1981, scientists also advanced the theory that "the weak underbelly" of the WAIS lay in the [[Amundsen Sea]] region, with the collapse of Thwaites and [[Pine Island Glacier]]s serving as the trigger for the subsequent collapse of the entire ice sheet.<ref name="Hughes1981">{{cite journal | doi-access=free |doi=10.3189/S002214300001159X |title=The weak underbelly of the West Antarctic ice sheet |year=1981 |last1=Hughes |first1=T. J. |journal=Journal of Glaciology |volume=27 |issue=97 |pages=518–525 }}</ref><ref name="NASAUnderbelly">{{cite web |title=The "Unstable" West Antarctic Ice Sheet: A Primer |date=12 May 2014 |publisher=[[NASA]] |url=https://www.nasa.gov/jpl/news/antarctic-ice-sheet-20140512/ |access-date = 8 July 2023 }}</ref> This theory was informed by radar measurement data from research flights over West Antarctica in the 1960s and 1970s, which had revealed that in [[Pine Island Bay]], the glacier bed slopes downwards at an angle, and lies well below the [[sea level]]. This [[topography]], in addition to proximity to powerful [[ocean current]]s, makes both glaciers particularly vulnerable to increases in [[ocean heat content]].<ref name="NASAUnderbelly" /><ref name="Dotto2022">{{Cite journal|last1=Dotto |first1=Tiago S. |last2=Heywood |first2=Karen J. |last3=Hall |first3=Rob A. |last4=Scambos |first4=Ted A. |last5=Zheng |first5=Yixi |last6=Nakayama |first6=Yoshihiro |last7=Hyogo |first7=Shuntaro |last8=Snow |first8=Tasha |last9=Wåhlin |first9=Anna K. |last10=Wild |first10=Christian |last11=Truffer |first11=Martin |last12=Muto |first12=Atsuhiro |last13=Alley |first13=Karen E. |last14=Boehme |first14=Lars |last15=Bortolotto |first15=Guilherme A. |last16=Tyler |first16=Scott W. |last17=Pettit |first17=Erin |date=21 December 2022 |title=Ocean variability beneath Thwaites Eastern Ice Shelf driven by the Pine Island Bay Gyre strength| display-authors= 3 |journal=Nature Communications|language=en |volume=13 |issue=1 |page=7840 |doi=10.1038/s41467-022-35499-5 |pmid=36543787 |pmc=9772408 |bibcode=2022NatCo..13.7840D }}</ref> Subsequent research reinforced the hypothesis that Thwaites is the single part of the [[cryosphere]] that would have the largest near-term impact on the sea levels, and that it is likely to disappear even in response to [[climate change]] which had already occurred.<ref>{{cite news|title=This Antarctic glacier is the biggest threat for rising sea levels. The race is on to understand it|url=https://www.washingtonpost.com/news/energy-environment/wp/2016/10/20/u-s-and-u-k-announce-major-research-mission-to-enormous-melting-antarctic-glacier|newspaper=[[The Washington Post]]|date=20 October 2016}}</ref> Similarly, there is now widespread agreement that its loss is likely to pave the way for the loss of the entire West Antarctic Ice Sheet,<ref name="VoosenSciMag" /><ref name="NASAUnderbelly" /><ref name="Feldmann2015" /> which would raise the sea levels by around {{convert|3.3|ft|m|sigfig=1|abbr=on}} over several centuries or millennia.<ref name="ThwaitesFacts" /><ref name="PappasLiveSci" />
 
▲Once the potential contribution of Thwaites to future sea level rise became better known, some stories have started to refer to it as the "Doomsday Glacier". The first known usage of that nickname was in a May 2017 [[Rolling Stone]] magazine article by Jeff Goodell,<ref name="GoodellRS">{{cite magazine |first=Jeff |last=Goodell |title=The Doomsday Glacier |date=9 May 2017 |url=https://www.rollingstone.com/politics/politics-features/the-doomsday-glacier-113792/ | magazine=[[Rolling Stone]] |access-date=8 July 2023 }}</ref> and it has subsequently been used more widely.<ref name="RowlattBBC">{{cite web |first=Justin |last=Rowlatt |url=https://www.bbc.com/news/science-environment-51097309 |title=Antarctica melting: Climate change and the journey to the 'doomsday glacier' |publisher=BBC News |date=28 January 2020 }}</ref><ref name="PappasLiveSci" /><ref name="BakerSciAm" /><ref name="FritzCNN" /> While some scientists have embraced the name,<ref>{{Cite journal |last1=Mackintosh |first1=Andrew |date=5 September 2022 |title=Thwaites Glacier and the bed beneath |journal=Nature Geoscience |volume=15 |issue=9 |language=en |pages=687–688 |doi=10.1038/s41561-022-01020-2 |bibcode=2022NatGe..15..687M |s2cid=252081115 }}</ref> many others, including leading researchers like Ted Scambos, [[Eric Rignot]], [[Helen Fricker]] and Robert Larter have criticized it as alarmist and inaccurate.<ref name="RyanCNET">{{cite web |first=Jackson |last=Ryan |url=https://www.cnet.com/science/climate/please-stop-calling-it-the-doomsday-glacier/ |title=Please Stop Calling It the 'Doomsday Glacier' |publisher=[[CNET]] |date=6 September 2022 }}</ref>
 
==Observations and predictions==
===Early observations===
▲[[File:Amundsen Sea Icebergs.jpg|thumb|The B-22 iceberg broke off from the Thwaites Glacier Tongue on March 15, 2002.]]
▲[[File:Dotto_2022_PIB_meltwater.png|thumb|left|Distribution of meltwater hotspots caused by ice losses in [[Pine Island Bay]], the location of both Thwaites (TEIS refers to Thwaites Eastern Ice Shelf) and Pine Island Glaciers.<ref name="Dotto2022" />]]
In 2001, an analysis of [[radar interferometry]] data from the Earth Remote Sensing Satellites 1 and 2 by Eric Rignot revealed that the grounding line of Thwaites Glacier had retreated by {{cvt|1.4|km}} between 1992 and 1996, while its strongly negative [[Glacier mass balance|mass balance]] (annual loss of around 16 billion tonnes of ice, equivalent to 17 cubic kilometers of volume) meant that the retreat was going to continue.<ref name="Rignot2001">{{Cite journal |last1=Rignot |first1=Eric |year=2001 |title=Evidence for rapid retreat and mass loss of Thwaites Glacier, West Antarctica |journal=Journal of Glaciology |url=https://www.cambridge.org/core/journals/journal-of-glaciology/article/evidence-for-rapid-retreat-and-mass-loss-of-thwaites-glacier-west-antarctica/BF1D2B7CA82360E5647E94D2B3E18773 |volume=47 |issue=157 |language=en |pages=213–222 |doi=10.3189/172756501781832340 |bibcode=2001JGlac..47..213R |s2cid=128683798 |doi-access=free }}</ref> Further analysis of this data suggested that each {{convert|0.1|C-change|F-change}} increase in [[ocean temperature]] would accelerate annual bottom-up melting by {{cvt|1|m}}.<ref>{{Cite journal |last1=Rignot |first1=Eric |last2=Jacobs |first2=Stanley S. |date=14 June 2002 |title=Rapid Bottom Melting Widespread near Antarctic Ice Sheet Grounding Lines |journal=Science |volume=296 |issue=5575 |language=en |pages=2020–2023 |doi=10.1126/science.1070942 |pmid=12065835 |bibcode=2002Sci...296.2020R |s2cid=749743 |url=https://www.escholarship.org/uc/item/1nj6x4t1 }}</ref> In 2002, a team of scientists from [[Chile]] and [[NASA]] on board a [[P-3 Orion]] from the Chilean Navy collected the first radar sounding and [[laser altimetry]] survey of the glacier, confirming the acceleration in thinning and retreat, and concluding that local seabed [[topography]] provides no obstacles to rapid retreat.<ref>{{Cite journal |last1=Rignot |first1=Eric |last2=Thomas |first2=Robert H. |last3=Kanagaratnam |first3=Pannir |last4=Casassa |first4=Gino |last5=Frederick |first5=Earl |last6=Gogineni |first6=Sivaprasad |last7=Krabill |first7=William |last8=Rivera |first8=Andrès |last9=Russell |first9=Robert |last10=Sontag |first10=John |year=2004 |title= Improved estimation of the mass balance of glaciers draining into the Amundsen Sea sector of West Antarctica from the CECS/NASA 2002 campaign|url=https://www.cambridge.org/core/journals/annals-of-glaciology/article/improved-estimation-of-the-mass-balance-of-glaciers-draining-into-the-amundsen-sea-sector-of-west-antarctica-from-the-cecsnasa-2002-campaign/CF0F3612575B1D1E59A2C2F9F8BAC181 |journal=Annals of Glaciology |volume=39 |pages=231–237 |language=en |doi=10.3189/172756404781813916 |s2cid=129780210 |doi-access=free }}</ref> These discoveries prompted an extensive airborne campaign in 2004-2005 by the [[University of Texas at Austin]],<ref>{{Cite journal |last1=Holt |first1=John W. |last2=Blankenship |first2=Donald D. |last3=Morse |first3=David L. |last4=Young |first4=Duncan A. |last5=Peters |first5=Matthew E. |last6=Kempf |first6=Scott D. |last7=Richter |first7=Thomas G. |last8=Vaughan |first8=David G. |last9=Corr |first9=Hugh F. J. |date=3 May 2006 |title=New boundary conditions for the West Antarctic Ice Sheet: Subglacial topography of the Thwaites and Smith glacier catchments |journal=Geophysical Research Letters |volume=33 |issue=9 |language=en |doi=10.1029/2005GL025561 |s2cid=18624664 |doi-access=free }}</ref> followed by NASA's IceBridge Campaign in 2009–2018. Geophysical data collected from IceBridge campaign flights showed that the most vulnerable parts of Thwaites Glacier sit {{cvt|1.5|mi|km}} below the sea level.<ref name="NASAUnderbelly" />
 
In 2011, an analysis of IceBridge data showed a rock ridge {{cvt|700|m}} tall, which helps to anchor the glacier and slows its glacier's slide into the sea.<ref>{{Cite web|url= https://www.earth.columbia.edu/articles/view/2904|title=Scientists Predict Faster Retreat for Antarctica’sAntarctica's Thwaites Glacier | publisher= The Earth Institute, Columbia University|website=earth.columbia.edu}}</ref> In early 2013, a minor speedup of ice flow near the glacier grounding line was detected, which was later attributed to the activity of [[subglacial lake]]s upstream of Thwaitesthe grounding line.<ref>{{Cite journal |last1=Siegfried |first1=Matthew R. |last2=Fricker |first2=Helen A. |date=26 January 2018 |title=Thirteen years of subglacial lake activity in Antarctica from multi-mission satellite altimetry |journal=Annals of Glaciology |language=en |volume=59 |issue=76pt1 |pages=42–55 |doi=10.1017/aog.2017.36 |bibcode=2018AnGla..59...42S |s2cid=134651986 |issn=0260-3055|doi-access=free }}</ref><ref>{{Cite web |url=https://scitechdaily.com/surprising-ebb-and-flow-of-vast-subglacial-lakes-revealed-by-cryosat/ |date=14 December 2020 |title=Surprising Ebb and Flow of Vast Subglacial Lakes Revealed by CryoSat |website=ScitechDaily }}</ref> Altogether, annual ice loss had increased substantially since Rignot's 2001 analysis: from around 16 billion tonnes of ice between 1992 and 1996<ref name="Rignot2001" /> to about 50 billion tons between 2002 and 2016. Cumulative ice loss over those 14 years was equivalent to a global sea level rise of 2.07 mm.<ref name="ThwaitesFacts" />▼
 
A 2014 paper noted that while the Thwaites Glacier was expected to add less than 0.25 mm of global sea level rise per year over the 21st century, this would eventually increase to over 1 mm per year during its "rapid collapse" phase.<ref name="Joughin2014" /> In 2018, a team of glaciologists, including Eric Rignot, had published projections of Thwaites Glacier contribution to sea level rise for the next 100 years. They estimated that the ice lost from Thwaites alone over the next 30 years would amount to 5 mm of sea level rise, but there was less certainty about 100-year ice loss, which could range between 14 and 42 mm depending on [[ice sheet dynamics]]. Further, their simulations couldn't represent the impact of the eastern ice shelf breaking up entirely.<ref name="Yu2018">{{Cite journal |last1=Yu |first1=Hongju |last2=Rignot |first2=Eric |last3=Seroussi |first3=Helene |last4=Morlighem |first4=Mathieu |date=11 December 2018 |title=Retreat of Thwaites Glacier, West Antarctica, over the next 100 years using various ice flow models, ice shelf melt scenarios and basal friction laws |url=https://tc.copernicus.org/articles/12/3861/2018/ |journal=The Cryosphere |volume=12 |issue=12 |pages=3861–3876 |language=en |doi=10.5194/tc-12-3861-2018 |doi-access=free }}</ref>
▲In 2011, an analysis of IceBridge data showed a rock ridge {{cvt|700|m}} tall, which helps to anchor the glacier and slows its glacier's slide into the sea.<ref>{{Cite web|url= https://www.earth.columbia.edu/articles/view/2904|title=Scientists Predict Faster Retreat for Antarctica’s Thwaites Glacier | publisher= The Earth Institute, Columbia University|website=earth.columbia.edu}}</ref> In early 2013, a minor speedup of ice flow near the glacier grounding line was detected, which was later attributed to the activity of [[subglacial lake]]s upstream of Thwaites.<ref>{{Cite journal |last1=Siegfried |first1=Matthew R. |last2=Fricker |first2=Helen A. |date=26 January 2018 |title=Thirteen years of subglacial lake activity in Antarctica from multi-mission satellite altimetry |journal=Annals of Glaciology |language=en |volume=59 |issue=76pt1 |pages=42–55 |doi=10.1017/aog.2017.36 |bibcode=2018AnGla..59...42S |s2cid=134651986 |issn=0260-3055|doi-access=free }}</ref><ref>{{Cite web |url=https://scitechdaily.com/surprising-ebb-and-flow-of-vast-subglacial-lakes-revealed-by-cryosat/ |date=14 December 2020 |title=Surprising Ebb and Flow of Vast Subglacial Lakes Revealed by CryoSat |website=ScitechDaily }}</ref>
 
===International Thwaites Glacier Collaboration===
Line 82 ⟶ 86:
|last14=Lawrence |first14=Justin D. |last15=Meister |first15=Matthew M. |last16=Clyne |first16=Elizabeth |last17=Basinski-Ferris |first17=Aurora |last18=Rignot |first18=Eric |last19=Queste |first19=Bastien Y. |last20=Boehme |first20=Lars |last21=Heywood |first21=Karen J. |last22=Anandakrishnan |first22=Sridhar |last23=Makinson |first23=Keith |date=15 February 2023 | display-authors= 3 |title=Suppressed basal melting in the eastern Thwaites Glacier grounding zone |journal=Nature |volume=614|issue=7948 |language=en |pages=479–485 |doi=10.1038/s41586-022-05586-0 |pmid=36792735 |pmc=9931584 |bibcode=2023Natur.614..479D |doi-access=free }}</ref><ref name="PappasLiveSci">{{Cite news |first=Stephanie |last=Pappas |url=https://www.livescience.com/doomsday-glacier-is-melting-slower-than-previously-thought-but-its-still-in-big-trouble |title=Doomsday Glacier is melting slower than previously thought — but it's still in big trouble|website=LiveScience |date=15 February 2023 |access-date=8 July 2023}}</ref><ref name="KorneiEos" >{{Cite web |last=Kornei |first=Katherine |title="Icefin" Investigates a Glacial Underbelly |date=15 March 2023 |url=https://eos.org/articles/icefin-investigates-a-glacial-underbelly |access-date=13 July 2023 |website=Eos |quote=Using hot water, they bored through the full thickness of Thwaites’s ice shelf—587 meters (0.4 mile)—until they reached water...Davis and his colleagues calculated that overall, the underside of Thwaites is melting far less rapidly than predicted by models.}}</ref>
[[File:Wild_2022_thwaites_shelf.png|thumb|upright=1.1|The comparison of current rates of retreat on the eastern side of Thwaites (left) and ones projected after the collapse of the Thwaites Ice Shelf.<ref name="Wild2022" /> This projection was challenged the following year.<ref name="Gudmundsson2023" />]]
In 2021, further ITGC research suggested that the Thwaites Ice Shelf, which currently restrains the eastern portion of the Thwaites Glacier, could start to collapse within five years.<ref name="Wild2022">{{Cite journal |last1=Wild |first1= Christian T. |last2=Alley |first2=Karen E. |last3=Muto |first3=Atsuhiro |last4=Truffer |first4=Martin |last5=Scambos |first5=Ted A. |last6=Pettit |first6=Erin C. Pettit |date=3 February 2022 |title=Weakening of the pinning point buttressing Thwaites Glacier, West Antarctica |url=https://tc.copernicus.org/articles/16/397/2022/ |journal=The Cryosphere |volume=16 |issue=2 |pages=397–417 |language=en |doi=10.5194/tc-16-397-2022 |bibcode= 2022TCry...16..397W |doi-access= free |hdl=20.500.12613/9340 |hdl-access=free }}</ref><ref name="CIRES">{{cite press release |last1=Weeman|first1=Katie|last2=Scambos|first2=Ted |title=The Threat from Thwaites: The Retreat of Antarctica's Riskiest Glacier| website= cires.colorado.edu |url= https://cires.colorado.edu/news/threat-thwaites-retreat-antarctica’santarctica%E2%80%99s-riskiest-glacier |publisher=Cooperative Institute for Research in Environmental Sciences, [[University of Colorado Boulder]] |date=13 December 2021 |access-date=14 December 2021|archive-date=25 September 2022|archive-url=https://web.archive.org/web/20220925210627/https://cires.colorado.edu/news/threat-thwaites-retreat-antarctica%E2%80%99s-riskiest-glacier|url-status=dead}}</ref><ref name="KaplanWaPo">{{cite news |last=Kaplan |first=Sarah |date=December 13, 2021 |title=Crucial Antarctic ice shelf could fail within five years, scientists say |url=https://www.washingtonpost.com/climate-environment/2021/12/13/thwaites-glacier-melt-antarctica/ |newspaper=[[The Washington Post]] |location=Washington DC |access-date=14 December 2021}}</ref> This would lead to a greater outflow from the glacier, increasing its annual contribution to sea level rise from 4% to 5% in the near term.<ref name="Gramling" /><ref name="VoosenSciMag" /><ref name="AmosBBC" /> Scientists had subsequently noted that "Things are evolving really rapidly here. It's daunting."<ref name="KaplanWaPo" /> In December 2021, the situation was described as worrisome. International Thwaites Glacier CollaborationITGC glaciologist [[Erin Pettit]] noted in an interview that Thwaites, along with the rest of the West Antarctic Ice Sheet, would start to see major losses "within decades" after the ice shelf's failure, and this would be especially pronounced if the [[Shared Socioeconomic Pathways|anthropogenic emission trajectory]] does not decrease by then. In her own words: "We’ll start to see some of that before I leave this Earth."<ref name="VoosenSciMag" />
 
===Other recent research===
[[File:Graham_2022_Thwaites_ridges.png|thumb|left|Diagram explaining how grounding line movement left behind "ribs" on the seafloor now used by the researchers to estimate glacier's past rates of retreat.<ref name="Graham2022" />]]
A 2022 study described the "rapid retreat" of the Thwaites Glacier, inferring its past movement in the pre-satellite era by analyzing "ribs" left behind after [[seabed gouging by ice]]. It found that at some point in the last two centuries, the glacier moved {{cvt|2.1|km}} per year, twice the rate it did between 2011–2019. This rate of retreat could reoccur if the glacier recedes and is dislodged beyond a sea bed that is currently keeping it somewhat stable.<ref name="Graham2022">{{Cite journal |last1= Graham |first1=Alastair G. C. |last2=Wåhlin |first2=Anna |last3=Hogan |first3=Kelly A. |last4=Nitsche |first4=Frank O. |last5=Heywood |first5=Karen J. |last6=Totten |first6=Rebecca L. |last7=Smith |first7=James A. |last8=Hillenbrand |first8=Claus-Dieter |last9=Simkins |first9=Lauren M. |last10=Anderson |first10=John B. |last11=Wellner |first11=Julia S. |last12=Larter |first12=Robert D. |date=5 September 2022 | display-authors= 3 |title=Rapid retreat of Thwaites Glacier in the pre-satellite era |journal=Nature Geoscience |volume=15 |issue=9 |language=en |pages=706–713 |doi=10.1038/s41561-022-01019-9 |bibcode=2022NatGe..15..706G |s2cid=252081206 |issn=1752-0908|doi-access=free }}</ref><ref name="FritzCNN">{{Cite web |last=Fritz |first=Angela |title='Doomsday' glacier,' which could raise sea level by several feet, is holding on 'by its fingernails,' scientists say |date=5 September 2022 |url=https://www.cnn.com/2022/09/05/world/thwaites-doomsday-glacier-sea-level-climate/index.html |access-date=6 September 2022 |publisher=CNN}}</ref><ref name="EosBarbuzano" >{{Cite web |last=Barbuzano |first=Javier |title=Seafloor Reveals a Period of Rapid Retreat for Thwaites Glacier |date=13 October 2022 |url=https://eos.org/articles/seafloor-reveals-a-period-of-rapid-retreat-for-thwaites-glacier |access-date=8 July 2023 |website=Eos}}</ref> In 2023, researchers found that at the end of [[Last Glacial Maximum]], an [[ice sheet]] covering what is now [[Norway]] retreated at 50 to 600 meters per day over the course of several days to months, far faster than any rate observed today, because its "bed", the ground it rested on, was completely flat. As Thwaites Glacier continues to retreat, the grounding line will eventually reach a similarly flat portion, and the researchers suggested that a part of the glacier could then disappear similarly quickly. This finding does not change the annual average melting rate for the rest of the glacier.<ref>{{Cite journal |last1=Batchelor |first1=Christine L. |last2=Christie |first2=Frazer D. W. |last3=Ottesen |first3=Dag |last4=Montelli |first4=Aleksandr |last5=Evans |first5=Jeffrey |last6=Dowdeswell |first6=Evelyn K. |last7=Bjarnadóttir |first7=Lilja R. |last8=Dowdeswell |first8=Julian A. |date=5 April 2023 |title=Rapid, buoyancy-driven ice-sheet retreat of hundreds of metres per day |journal=Nature |language=en |volume=617 |issue=7959 |pages=105–110 |doi=10.1038/s41586-023-05876-1 |pmid=37020019 |bibcode=2023Natur.617..105B |s2cid=257983775 }}</ref><ref>{{Cite web |title=Ice sheets can collapse faster than previously thought possible |date=5 April 2023 |url=https://phys.org/news/2023-04-ice-sheets-collapse-faster-previously.html |access-date=7 July 2023 |website=[[Phys.org]]}}</ref>
 
A model created in 2023 suggested that as the outer ice at Thwaites melts due to warm water currents, it erodes in a way which strengthens the flow of those currents. While this [[climate change feedback]] wasn't a surprise, the model estimated that over just the past 12 years, this feedback accelerated melting by 30%, or as much as what is expected from a whole century of a high-emission [[climate change scenario]] in the absence of this feedback. If confirmed, this would mean that the melting of Thwaites Glacier can be expected to accelerate at a similar rate for the next century, regardless of whether [[ocean temperature]] keeps going up, or stops increasing at all.<ref name="Holland2023">{{cite journal |last1=Holland |first1=Paul R. |last2=Bevan |first2=Suzanne L. |last3=Luckman |first3=Adrian J. |title=Strong Ocean Melting Feedback During the Recent Retreat of Thwaites Glacier |date=11 April 2023 |journal=Geophysical Research Letters |volume=50 |issue=8 |doi=10.1029/2023GL103088 |bibcode=2023GeoRL..5003088H | doi-access=free }}</ref> Other 2023 research suggests that over the 21st century, water temperatures in the entire [[Amundsen Sea]] are likely to increase at triple the historical rate even with low or "medium" atmospheric warming and even faster with high warming, which further "worsens the outlook" for the glacier.<ref>{{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 |url=https://www.nature.com/articles/s41558-023-01818-x |access-date=26 October 2023|doi-access=free }}</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> ▼
 
In 2024, research indicated that instead of a relatively narrow ''grounding line'' which separates the parts of the glacier exposed to water and those safely behind them, there is a wider ''grounding zone'' of {{cvt|2-6|km}} which is regularly exposed to water. Some areas of the glacier are additionally exposed to meltwater flowing another {{cvt|6|km}} inwards during the strong spring tides. This increased exposure to meltwater would increase the rate of ice loss, potentially doubling the rate of the previous projections.<ref>{{cite journal |last1=Rignot |first1=Eric |last2=Ciracì |first2=Enrico |last3=Tolpekin |first3=Valentyn |last4=Wollersheim |first4=Michael |last5=Dow |first5=Christine |title=Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica |date=20 May 2024 |journal=Proceedings of the National Academy of Sciences |volume=121 |issue=22 |page=e2404766121 |doi=10.1073/pnas.2404766121 |quote="Our results confirm the existence of kilometer-size grounding zones on the main trunk of Thwaites Glacier. Models with km-size grounding zones and vigorous ice melt will produce higher projections of glacier loss, possibly by a factor of 2." |doi-access=free |pmc=11145208 }}</ref>
▲A model created in 2023 suggested that as the outer ice at Thwaites melts due to warm water currents, it erodes in a way which strengthens the flow of those currents. While this [[climate change feedback]] wasn't a surprise, the model estimated that over just the past 12 years, this feedback accelerated melting by 30%, or as much as what is expected from a whole century of a high-emission [[climate change scenario]] in the absence of this feedback. If confirmed, this would mean that the melting of Thwaites Glacier can be expected to accelerate at a similar rate for the next century, regardless of whether [[ocean temperature]] keeps going up, or stops increasing at all.<ref name="Holland2023">{{cite journal |last1=Holland |first1=Paul R. |last2=Bevan |first2=Suzanne L. |last3=Luckman |first3=Adrian J. |title=Strong Ocean Melting Feedback During the Recent Retreat of Thwaites Glacier |date=11 April 2023 |journal=Geophysical Research Letters |volume=50 |issue=8 |doi=10.1029/2023GL103088 |bibcode=2023GeoRL..5003088H | doi-access=free }}</ref>
 
===Predicted timelines for glacier collapse===
[[File:Schwans_2023_500_years.png|thumb|Contribution to sea level rise from a modelled area of Thwaites Glacier under high- and low warming (HSO and LSO) and high (m1) and low (m8) friction. Top shows both warming scenarios in a high-detail model, while middle and bottom graphics show the HSO and LSO scenarios in low-resolution models.]]
A 2014 study, using satellite measurements and computer models, predicted that only the lowest possible warming offered any chance of preserving Thwaites Glacier: otherwise, it will inevitably reach the point of "rapid and irreversible collapse" overin the next 200 to 900 years. Once that happens, its retreat would add over 1 mm to the global annual sea level rise,000 yearsup until it disappears.<ref>{{cite web |title=Irreversible collapse of Antarctic glaciers has begun, studies say |url=http://www.latimes.com/science/environment/la-sci-0513-antarctic-ice-sheet-20140513-story.html |work=Los Angeles Times |access-date=13 May 2014 |date=12 May 2014}}</ref><ref>{{cite news|last=Sumner |first=Thomas |date=8 April 2016 |title=Changing climate: 10 years after An Inconvenient Truth |url=https://www.sciencenews.org/article/changing-climate-10-years-after-inconvenient-truth |newspaper=[[Science News]] |access-date=25 July 2016 }}</ref><ref name="Feldmann2015">{{cite journal|date=17 November 2015|title=Collapse of the West Antarctic Ice Sheet after local destabilization of the Amundsen Basin|journal=Proceedings of the National Academy of Sciences|volume=112|pages= 14191–14196|doi=10.1073/pnas.1512482112|pmc=4655561|pmid=26578762 | last1 = Feldmann | first1 = J | last2 = Levermann | first2 = A|issue=46|bibcode=2015PNAS..11214191F|doi-access=free}}</ref><ref>{{cite journal|date=12 May 2014|title=Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica, from 1992 to 2011|url= https://escholarship.org/content/qt0wz826xt/qt0wz826xt.pdf?t=nu5md1|journal=Geophysical Research Letters|volume= 41|pages= 3502–3509|doi=10.1002/2014GL060140| last1 = Rignot | first1 = E.|issue=10|bibcode=2014GeoRL..41.3502R|s2cid=55646040 }}</ref><ref name="Joughin2014">{{cite journal|date=16 May 2014|title=Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica|journal= Science|volume=344|pages=735–738|doi=10.1126/science.1249055| last1 = Joughin | first1 = I.|issue=6185|pmid= 24821948|bibcode=2014Sci...344..735J|s2cid=206554077|doi-access=free}}</ref><ref>{{Cite web|url= https://news.stanford.edu/2019/09/02/vintage-film-reveals-antarctic-glacier-melting/|title=Vintage film reveals Antarctic glacier melting|last=Tucker|first=Danielle Torrent|date=2 September 2019|website=Stanford News|language=en|access-date=7 September 2019}}</ref>
 
A 2022 assessment of [[tipping points in the climate system]] did not consider Thwaites Glacier on its own, but it did note that the entire West Antarctic Ice Sheet would most likely take 2,000 years to disintegrate entirely once it crosses its tipping point, and the minimum plausible timescale is 500 years, and could be as long as 13,000 years. It also noted that this tipping point for the entire ice sheet is no more than {{convert|3|C-change|F-change}} of global warming away, and is very likely to be triggered around the near-future levels of {{convert|1.5|C-change|F-change}}: at worst, it may have even been triggered by now, after the warming passed {{convert|1|C-change|F-change}} in recentthe yearsearly 21st century.<ref name="Getting tipsy">{{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 |display-authors= 3 |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="Explainer">{{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>
 
In May 2023, a modelling study considered the future of Thwaites Glacier over the course of 500 years. Due to computational limitations, it was only able to simulate about two-thirds of the glacier catchment (volume of ice equivalent to {{cvt|40|cm|frac=2}} of the global [[sea level rise]], rather than the {{cvt|65|cm|frac=2}} contained in the full glacier). It found that the uncertainty about glacier bed friction was almost as important as the future ocean temperature. Another finding was that lower-resolution models (those which simulated the glacier as a "mesh" of {{cvt|20|sqkm}} areas) consistently estimated faster break-up than the more detailed models with mesh size of {{cvt|6.5|sqkm}}. While in the less-detailed models, practically the entirety of the simulated area was lost around a 250-year mark under the combination of high warming and low friction, higher-resolution simulation showed that about quarter would remain under those conditions, to be lost over 100 more years. Under high warming yet high seabed friction, a quarter was still left at the end of 500 years in the detailed simulations. The same outcome occurred under low warming and low friction. With low warming and high friction, over half of the studied area remained after 500 years.<ref name="Schwans2023">{{Cite journal |last1=Schwans |first1=Emily |last2=Parizek |first2=Byron R. |last3=Alley |first3=Richard B. |last4=Anandakrishnan |first4=Sridhar |last5=Morlighem |first5=Mathieu M. |date=9 May 2023 |title=Model insights into bed control on retreat of Thwaites Glacier, West Antarctica |url=https://www.cambridge.org/core/journals/journal-of-glaciology/article/model-insights-into-bed-control-on-retreat-of-thwaites-glacier-west-antarctica/4F3E4E4566CDAF1D143C08F058CDAE3F |journal=Journal of Glaciology |volume=69 |issue=277 |pages=1–191241–1259 |language=en |doi=10.1017/jog.2023.13 |s2cid=258600944 |doi-access=free }}</ref>
 
==Engineering options for stabilization==
[[File:Wolovick2018_Thwaites_sill_timelines.png|thumb|left|upright=2.2|A proposed "underwater sill" blocking 50% of warm water flows heading for the glacier could have the potential to delay its collapse and the resultant sea level rise by many centuries.<ref name="Wolovick2018" />]]
{{See also|Climate engineering}}
Some engineering interventions have been proposed for Thwaites Glacier and the nearby [[Pine Island Glacier]] to physically stabilize its ice physically, or to preserve it. byThese blockinginterventions would block the flow of warm ocean water, which currently renders the collapse of these two glaciers practically inevitable even without further warming.<ref name="Joughin2014" /><ref name="MIT2022" /> A proposal from 2018 included building sills at the Thwaites' [[grounding line]] to either physically reinforce it, or to block some fraction of warm water flow. The former would be the simplest intervention, yet still equivalent to "the largest civil engineering projects that humanity has ever attempted":. itIt is also only 30% likely to work. Constructions blocking even 50% of the warm water flow are expected to be far more effective, yet far more difficult as well.<ref name="Wolovick2018">{{Cite journal |last1=Wolovick |first1=Michael J. |last2=Moore |first2=John C. |date=20 September 2018 |title=Stopping the flood: could we use targeted geoengineering to mitigate sea level rise? |url=https://tc.copernicus.org/articles/16/397/2022/ |journal=The Cryosphere |volume=12 |issue=9 |pages=2955–2967 |language=en |doi=10.5194/tc-12-2955-2018 |bibcode=2018TCry...12.2955W |s2cid=52969664 |doi-access=free }}</ref> Further, someSome researchers dissented, arguingargued that this proposal could be ineffective, or even accelerate sea level rise.<ref name="Moon2018">{{Cite journal |last1=Moon |first1=Twila A. |title=Geoengineering might speed glacier melt |date=25 April 2018 |journal=Nature |volume=556 |issue=7702 |language=en |pages=436 |doi=10.1038/d41586-018-04897-5 |pmid=29695853 |bibcode=2018Natur.556R.436M |doi-access=free }}</ref> The original authors haveof the original proposal suggested attempting this intervention on smaller sites, like the [[Jakobshavn Glacier]] in [[Greenland]], as a test run,.<ref name="Wolovick2018" /><ref name="MIT2022" /> asThey well asalso acknowledgingacknowledged that this intervention cannot prevent [[sea level rise]] from the increased [[ocean heat content]], and would be ineffective in the long run without [[greenhouse gas emission]] reductions.<ref name="Wolovick2018" />
 
In 2023, a modified proposal was tabled: it was proposed that an installation of underwater "''curtains"'', made out of a flexible material and anchored to the [[Amundsen Sea]] floor would be able to interrupt warm water flow. whileThis reducingapproach would reduce costs and increasingincrease theirthe longevity of the material (conservatively estimated at 25 years for curtain elements and up to 100 years for the foundations) relative to more rigid structures. With them in place, Thwaites Ice Shelf and Pine Island Ice Shelf would presumably be able to regrow to a state itthey last had a century ago, thus stabilizing these glaciers.<ref name="Wolovick2023a" /><ref name="Wolovick2023b" /><ref name="MIT2022">{{Cite web |author=Temple |first=James Temple|date=14 January 2022 |title=The radical intervention that might save the "doomsday" glacier |url=https://www.technologyreview.com/2022/01/14/1043523/save-doomsday-thwaites-glacier-antarctica/ |date=14 January 2022 |access-date=19 July 2023 |website=MIT Technology Review |language=en}}</ref> To achieve this, the curtains would have to be placed at a depth of around {{convert|600|m|mi|abbr=off}} (to avoid damage from [[iceberg]]s which would be regularly drifting above) and be {{cvt|80|km}} long. The authors acknowledged that while work on this scale would be unprecedented and face many challenges in the ArcticAntarctic (including [[polar night]] and the currently insufficient numbers of specialized polar ships and underwater vessels), it would also not require any new technology and there is already experience of laying down [[pipeline]]s at such depths.<ref name="Wolovick2023a" /><ref name="Wolovick2023b" />
[[File:Wolovick2023_Thwaites_curtain.jpeg|thumb|upright=1.6|Diagram of a proposed "curtain".<ref name="Wolovick2023a" />]]
The authors estimated that this project would take a decade to construct, at $40–80 billion initial cost, while the ongoing maintenance would cost $1–2 billion a year.<ref name="Wolovick2023a" /><ref name="Wolovick2023b" /> Yet, a single [[seawall]] capable of protecting the entire [[New York City]] may cost twice as much on its own,<ref name="MIT2022" /> and the global costs of [[climate change adaptation|adaptation]] to [[sea level rise]] caused by the glaciers' collapse are estimated to reach $40 billion annually:<ref name="Wolovick2023a" /><ref name="Wolovick2023b" /> The authors also suggested that their proposal would be competitive with the other "[[climate engineering]]" proposals like [[stratospheric aerosol injection]] (SAI) or [[carbon dioxide removal]] (CDR), as while those would stop a much larger spectrum of climate change impacts, their estimated annual costs range from $7–70 billion for SAI to $160–4500 billion for CDR powerful enough to help meet the {{convert|1.5|C-change|F-change}} [[Paris Agreement]] target.<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>
 
== See also ==
Retrieved from "https://en.wikipedia.org/wiki/Thwaites_Glacier"