Editing Climate of Antarctica (section)

==Ice cover==
Nearly all of Antarctica is covered by a sheet of ice that is, on average, at least {{convert|1500|m|ft|sigfig=1|abbr=on}} thick. Antarctica contains 90% of the world's [[ice]] and more than 70% of its [[fresh water]]. If all the land-ice covering Antarctica were to melt—around {{convert|30|e6km3|e6cumi|abbr=on}} of ice—the seas would rise by over {{convert|60|m|ft|abbr=on}}.<ref>{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113|title=Climate Change 2001: The Scientific Basis|publisher=Grida.no|access-date=27 March 2011|url-status=dead|archive-url=https://web.archive.org/web/20071216235037/http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113|archive-date=16 December 2007}}</ref> The Antarctic is so cold that even with increases of a few degrees, temperatures would generally remain below the melting point of ice. Higher temperatures are expected to lead to more precipitation, which takes the form of snow. This would increase the amount of ice in Antarctica, offsetting approximately one third of the expected sea level rise from thermal expansion of the oceans.<ref>{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/428.htm|title=Climate Change 2001: The Scientific Basis|publisher=Grida.no|access-date=27 March 2011|url-status=dead|archive-url=https://web.archive.org/web/20110514002354/http://www.grida.no/climate/ipcc_tar/wg1/428.htm|archive-date=14 May 2011}}</ref>
During a recent{{when|date=February 2020}} decade, East Antarctica thickened at an average rate of about {{convert|1.8|cm|in|frac=16|abbr=on}} per year while West Antarctica showed an overall thinning of {{convert|0.9|cm|in|frac=16|abbr=on}} per year.<ref>{{cite journal|vauthors=Davis CH, Li Y, McConnell JR, Frey MM, Hanna E |s2cid=31797055 |year=2005 |title=Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise |journal=Science |volume=308 |issue=5730 |pages=1898–1901 |doi=10.1126/science.1110662 |bibcode=2005Sci...308.1898D |pmid=15905362|doi-access=free }}</ref> For the contribution of Antarctica to present and [[future sea level]] change, see [[sea level rise]]. Because ice flows, albeit slowly, the ice within the ice sheet is younger than the age of the sheet itself.

{| class="wikitable"
|+ Morphometric data for Antarctica (from Drewry, 1983)
! rowspan=2|Surface
! colspan=2|Area
!rowspan=2|Mean ice<br>thickness <br/> (m)
! colspan=2|Volume
|-
!(km<sup>2</sup>)
!Percent
!(km<sup>3</sup>)
!Percent
|-
| Inland ice sheet
| style="text-align: right;" | 11,965,700
| style="text-align: right;" | 85.97
| style="text-align: right;" | 2,450
| style="text-align: right;" | 29,324,700
| style="text-align: right;" | 97.39
|-
| Ice shelves
| style="text-align: right;" | 1,541,710
| style="text-align: right;" | 11.08
| style="text-align: right;" | 475
| style="text-align: right;" | 731,900
| style="text-align: right;" | 2.43
|-
| [[Ice rise]]s
| style="text-align: right;" | 78,970
| style="text-align: right;" | 0.57
| style="text-align: right;" | 670
| style="text-align: right;" | 53,100
| style="text-align: right;" | 0.18
|-
! Glacier ice (total)
| style="text-align: right;" | 13,586,380
| &nbsp;
| style="text-align: right;" | 2,160
| style="text-align: right;" | 30,109,800{{efn-ua|name=ice-volume-rounding}}
|
|-
| Rock outcrop
| style="text-align: right;" | 331,690
| style="text-align: right;" | 2.38
|
|
|
|-
! Antarctica (total)
| style="text-align: right;" | 13,918,070
| style="text-align: right;" | 100.00
| style="text-align: right;" | 2,160
| style="text-align: right;" | 30,109,800{{efn-ua|name=ice-volume-rounding}}
| style="text-align: right;" | 100.00
|}
{{notelist-ua|refs={{efn-ua|name=ice-volume-rounding|text=The total ice volume is different from the sum of the component parts because individual figures have been rounded.}}}}
{| class="wikitable"
|+ Regional ice data (from Drewry and others, 1982; Drewry, 1983)
! Region
! Area <br/> (km<sup>2</sup>)
! Mean ice<br/>thickness <br/> (m)
! Volume <br/> (km<sup>3</sup>)
|-
! colspan=4 style="background:#FFFFCC;"|East Antarctica
|-
| Inland ice
| style="text-align: right;" | 9,855,570
| style="text-align: right;" | 2,630
| style="text-align: right;" | 25,920,100
|-
| Ice shelves
| style="text-align: right;" | 293,510
| style="text-align: right;" | 400
| style="text-align: right;" | 117,400
|-
| Ice rises
| style="text-align: right;" | 4,090
| style="text-align: right;" | 400
| style="text-align: right;" | 1,600
|-
! colspan=4 style="background:#FFFFCC;"|West Antarctica (excluding Antarctic Peninsula)
|-
| [[West Antarctic Ice Sheet|Inland ice sheet]]
| style="text-align: right;" | 1,809,760
| style="text-align: right;" | 1,780
| style="text-align: right;" | 3,221,400
|-
| Ice shelves
| style="text-align: right;" | 104,860
| style="text-align: right;" | 375
| style="text-align: right;" | 39,300
|-
| Ice rises
| style="text-align: right;" | 3,550
| style="text-align: right;" | 375
| style="text-align: right;" | 1,300
|-
! colspan=4 style="background:#FFFFCC;"|[[Antarctic Peninsula]]
|-
| Inland ice sheet
| style="text-align: right;" | 300,380
| style="text-align: right;" | 610
| style="text-align: right;" | 183,200
|-
| Ice shelves
| style="text-align: right;" | 144,750
| style="text-align: right;" | 300
| style="text-align: right;" | 43,400
|-
| Ice rises
| style="text-align: right;" | 1,570
| style="text-align: right;" | 300
| style="text-align: right;" | 500
|-
! colspan=4 style="background:#FFFFCC;"|[[Ross Ice Shelf]]
|-
| Ice shelf
| style="text-align: right;" | 525,840
| style="text-align: right;" | 427
| style="text-align: right;" | 224,500
|-
| Ice rises
| style="text-align: right;" | 10,320
| style="text-align: right;" | 500
| style="text-align: right;" | 5,100
|-
!colspan=4 style="background:#FFFFCC;"| [[Filchner-Ronne Ice Shelf]]
|-
| Ice shelf
| style="text-align: right;" | 472,760
| style="text-align: right;" | 650
| style="text-align: right;" | 307,300
|-
| Ice rises
| style="text-align: right;" | 59,440
| style="text-align: right;" | 750
| style="text-align: right;" | 44,600
|}

===Ice shelves===
[[File:Antarctica ice shelves-en.svg|thumb|Antarctic ice shelves, 1998]]
About 75% of the coastline of Antarctica is [[ice shelf]]. The majority of ice shelf consists of floating ice, and a lesser amount consists of glaciers that move slowly from the land mass into the sea. Ice shelves lose mass through breakup of glacial ice ([[Ice calving|calving]]), or [[Ice-sheet dynamics#Basal melt|basal melting]] due to warm ocean water under the ice.<ref>{{cite journal|journal=Science |title=Ice-Shelf Melting Around Antarctica |author1=E. Rignot |author2=S. Jacobs |author3=J. Mouginot |author4=B. Scheuchl |doi=10.1126/science.1235798 |bibcode=2013Sci...341..266R |volume=341 |issue=6143 |pages=266–270 |pmid=23765278 |year=2013|s2cid=206548095 |doi-access=free }}</ref>

Melting or breakup of floating shelf ice does not directly affect global sea levels; however, ice shelves have a buttressing effect on the ice flow behind them. If ice shelves break up, the ice flow behind them may accelerate, resulting in increasing melt of the Antarctic ice sheet and an increasing contribution to sea level rise.

Known changes in coastline ice around the Antarctic Peninsula:
* 1936–1989: [[Wordie Ice Shelf]] significantly reduced in size.
* 1995: Ice in the [[Prince Gustav Channel]] disintegrated.
* Parts of the [[Larsen Ice Shelf]] broke up in recent decades.
** 1995: The Larsen A ice shelf disintegrated in January 1995.
** 2001: {{convert|3,250|km2|sqmi|abbr=on}} of the Larsen B ice shelf disintegrated in February 2001. It had been gradually retreating before the breakup event.
** 2015: A study concluded that the remaining ''Larsen B'' ice-shelf will disintegrate by the end of the decade, based on observations of faster flow and rapid thinning of glaciers in the area.<ref>{{cite web|title=NASA Study Shows Antarctica's Larsen B Ice Shelf Nearing Its Final Act|url=http://www.nasa.gov/press-release/nasa-study-shows-antarctica-s-larsen-b-ice-shelf-nearing-its-final-act|author=NASA|date=14 May 2015|url-status=live|archive-url=https://web.archive.org/web/20150609032810/http://www.nasa.gov/press-release/nasa-study-shows-antarctica-s-larsen-b-ice-shelf-nearing-its-final-act/|archive-date=9 June 2015}}</ref>

The [[George VI Ice Shelf]], which may be on the brink of instability,<ref>{{cite web|url=http://www.antarctica.ac.uk/BAS_Science/Highlights/2001/george_vi.html |title=Millennial-scale variability of George VI Ice Shelf, Antarctic Peninsula |publisher=Natural Environment Research Council |access-date=8 June 2015 |first1=Mike |last1=Bentley |first2=Dominic |last2=Hodgson |archive-url=https://web.archive.org/web/20020912045816/http://www.antarctica.ac.uk/BAS_Science/Highlights/2001/george_vi.html |archive-date=12 September 2002}}</ref> has probably existed for approximately 8,000 years, after melting 1,500 years earlier.<ref>{{cite web|url=http://igloo.gsfc.nasa.gov/wais/pastmeetings/abstracts00/Bentley2.htm |title=Holocene Instability of the George VI Ice Shelf, Antarctic Peninsula |access-date=8 June 2015 |last1=Bentley|first1= M.J.|last2= Hjort|first2= C. |last3=Ingolfsson|first3= O. |last4=Sugden|first4= D.E.|url-status=dead |archive-url=https://web.archive.org/web/20041020150823/http://igloo.gsfc.nasa.gov/wais/pastmeetings/abstracts00/Bentley2.htm | archive-date=20 October 2004}}</ref> Warm ocean currents may have been the cause of the melting.<ref>{{cite web|url=http://www.antarctica.ac.uk/News_and_Information/Press_Releases/story.php?id=160 |title=Press Release – New Year's Honours for British Antarctic Survey Personnel |publisher=[[British Antarctic Survey]] |date=5 January 2006 |url-status=dead |archive-url=https://web.archive.org/web/20061215053832/http://www.antarctica.ac.uk/News_and_Information/Press_Releases/story.php?id=160 |archive-date=15 December 2006}}</ref> Not only are the ice sheets losing mass, they are losing mass at an accelerating rate.<ref>{{cite web|url=https://www.nasa.gov/topics/earth/features/20100108_Is_Antarctica_Melting.html |title=NASA - Is Antarctica Melting? |website=www.nasa.gov |url-status=live |archive-url=https://web.archive.org/web/20161212153658/https://www.nasa.gov/topics/earth/features/20100108_Is_Antarctica_Melting.html |archive-date=12 December 2016}}</ref>