Editing Antarctic ice sheet (section)

== Geography ==
{{See also|Geography of Antarctica}}
[[File:AA bedrock bedmap2.4960.tif|thumb|The bedrock topography of Antarctica, critical to understand dynamic motion of the continental ice sheets.<ref name="SVS2013"/>]]
The Antarctic ice sheet covers an area of almost {{convert|14|e6km2|abbr=off}} and contains {{convert|26.5|e6km3|cumi|abbr=off}} of ice.<ref name="AmosBBC2013">{{cite web|last=Amos |first=Jonathan |url=https://www.bbc.co.uk/news/science-environment-21692423 |title=Antarctic ice volume measured |work=BBC News |date=2013-03-08 |access-date=2014-01-28}}</ref> A cubic kilometer of ice weighs approximately 0.92&nbsp;metric gigatonnes, meaning that the ice sheet weighs about 24,380,000 gigatonnes. This ice is equivalent to around 61% of all fresh water on Earth.<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> 
The only other currently existing [[ice sheet]] on Earth is the [[Greenland ice sheet]] in the [[Arctic]].<ref name="RobinsonUMC">{{Cite web |last=Robinson |first=Ben |date=15 April 2019 |title=Scientists chart history of Greenland Ice Sheet for first time |url=https://www.manchester.ac.uk/discover/news/scientists-chart-history-of-greenland-ice-sheet-for-first-time/ |website=[[The University of Manchester]] |access-date=7 December 2023 |archive-date=7 December 2023 |archive-url=https://web.archive.org/web/20231207190313/https://www.manchester.ac.uk/discover/news/scientists-chart-history-of-greenland-ice-sheet-for-first-time/ |url-status=live }}</ref>

The Antarctic ice sheet is divided by the [[Transantarctic Mountains]] into two unequal sections called the [[East Antarctic Ice Sheet]] (EAIS) and the smaller [[West Antarctic Ice Sheet]] (WAIS). Some glaciologists consider ice cover over the relatively small [[Antarctic Peninsula]] (also in West Antarctica) to be the third ice sheet in Antarctica,<ref name="IMBIE">{{cite web |last1=Shepherd |first1=Andrew |title=Antarctica and Greenland Ice Sheet Drainage Basins |url=http://imbie.org/imbie-3/drainage-basins/ |website=imbie.org |access-date=31 January 2024 |date=18 January 2024 |quote="Antarctica is divided into the West Antarctic Ice Sheet, East Antarctic Ice Sheet and Antarctic Peninsula based on historical definitions plus information from modern-day DEM and ice velocity data."}}</ref><ref name="AR6_WGI_AnnexVII">IPCC, 2021: Annex VII: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_AnnexVII.pdf Glossary] [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, S. Semenov, A. Reisinger (eds.)]. 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, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.</ref>{{Rp|page=2234}} in part because its [[drainage basin]]s are very distinct from the WAIS.<ref name="Rignot2019">{{cite journal |last1=Rignot |first1=Eric |last2=Mouginot |first2=Jérémie |last3=Scheuchl |first3=Bernd |last4=van den Broeke |first4=Michiel |last5=van Wessem |first5=Melchior J. |last6=Morlighem |first6=Mathieu |title=Four decades of Antarctic Ice Sheet mass balance from 1979–2017 |journal=Proceedings of the National Academy of Sciences |date=22 January 2019 |volume=116 |issue=4 |pages=1095–1103 |doi=10.1073/pnas.1812883116|doi-access=free |pmid=30642972 |pmc=6347714 |bibcode=2019PNAS..116.1095R }}</ref> Collectively, these ice sheets have an average thickness of around {{convert|2|km|mi}},<ref name=NSFfactsheet>{{Cite web|title=Ice Sheets|publisher=National Science Foundation|url=https://www.nsf.gov/geo/opp/antarct/science/icesheet.jsp}}</ref> Even the Transantarctic Mountains are largely covered by ice, with only some mountain summits and the [[McMurdo Dry Valleys]] being ice-free in the present. Some coastal areas also have exposed bedrock that is not covered by ice.<ref name="Swithinbank1988">{{cite journal |last1=Swithinbank |first1=Charles |editor1-last=Williams Jr. |editor1-first=Richard S. |editor2-last=Ferrigno |editor2-first=Jane G. |title=Glaciers of Antarctica |journal=Satellite Image Atlas of Glaciers of the World |date=1988 |volume=U.S. Geological Survey Professional Paper |issue=1386-B |doi=10.3133/pp1386B |bibcode=1988usgs.rept...12W |url=https://pubs.usgs.gov/pp/p1386b/p1386b.pdf}}</ref> During the [[Late Cenozoic Ice Age]], many of those areas had been covered by ice as well.<ref name="Prentice1998">{{cite book |last1=Prentice |first1=Michael L. |last2=Kleman |first2=Johan L. |last3=Stroeven |first3=Arjen P. |title=Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica |date=1998 |publisher=American Geophysical Union |isbn=9781118668313 |pages=1–38 |url=https://doi.org/10.1029/AR072p0001 |chapter=The Composite Glacial Erosional Landscape of the Northern Mcmurdo Dry Valleys: Implications for Antarctic Tertiary Glacial History|doi=10.1029/AR072p0001 }}</ref><ref name="Mackintosh2014">{{cite journal |author1=Andrew N. Mackintosh |author2=Elie Verleyen |author3=Philip E. O'Brien |author4=Duanne A. White |author5=R. Selwyn Jones |author6=Robert McKay |author7=Robert Dunbar |author8=Damian B. Gore |author9=David Fink |author10=Alexandra L. Post |author11=Hideki Miura |author12=Amy Leventer |author13=Ian Goodwin |author14=Dominic A. Hodgson |author15=Katherine Lilly |author16=Xavier Crosta |author17=Nicholas R. Golledge |author18=Bernd Wagner |author19=Sonja Berg |author20=Tas van Ommen |author21=Dan Zwartz |author22=Stephen J. Roberts |author23=Wim Vyverman |author24=Guillaume Masse |title=Retreat history of the East Antarctic Ice Sheet since the Last Glacial Maximum |journal=Quaternary Science Reviews |date=2014 |volume=100 |pages=10–30 |doi=10.1016/j.quascirev.2013.07.024 |bibcode=2014QSRv..100...10M |issn=0277-3791|hdl=1854/LU-5767317 |hdl-access=free }}</ref>

The EAIS rests on a major land mass, but the bed of the WAIS is, in places, more than {{Convert|2,500|m|ft|abbr=off|sp=us}} below [[sea level]]. It would be [[seabed]] if the ice sheet were not there. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies below sea level and its edges flow into floating ice shelves.<ref name="BEDMAP2-2013" /><ref name="Hale2014">{{cite web |last1=Hale |first1=George |title=East and West: The Geography of Antarctica |url=https://blogs.nasa.gov/icebridge/2014/11/19/east-and-west-the-geography-of-antarctica/ |website=Operation IceBridge |publisher=National Aeronautics and Space Administration |access-date=31 January 2024 |date=19 November 2014}}</ref> The WAIS is bounded by the [[Ross Ice Shelf]], the [[Filchner–Ronne Ice Shelf|Filchner-Ronne Ice Shelf]], and [[outlet glacier]]s that drain into the [[Amundsen Sea]].<ref name="GoddardCryo">{{cite web |title=Antarctic and Greenland Drainage Systems |url=https://earth.gsfc.nasa.gov/cryo/data/polar-altimetry/antarctic-and-greenland-drainage-systems |website=NASA Earth Sciences |publisher=Goddard Earth Sciences Division Projects: Cryospheric Sciences |access-date=31 January 2024 |date=19 January 2024 |quote=Our definitions of the West Antarctic ice sheet (systems 18-23 and 1), the East Antarctic ice sheet (systems 2-17), and the Antarctic Peninsula (systems 24-27) allocate the drainage systems according to ice provenance with separation of East and West Antarctica approximately along the Transantarctic Mountains.}}</ref> [[Thwaites Glacier]] and [[Pine Island Glacier]] are the two most important outlet glaciers.<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>