Editing Ice (section)

=== On land ===
[[File:AA bedrock surface.4960.tif|thumb|[[NASA]] image of the Antarctic ice sheet]]
The largest ice formations on Earth are the two [[ice sheet]]s which almost completely cover the world's largest island, [[Greenland]], and the continent of [[Antarctica]]. These ice sheets have an average thickness of over {{convert|1|km|mi|1|abbr=on}} and have existed for millions of years.<ref name="BBC2017">{{cite web |title=How Greenland would look without its ice sheet |date=14 December 2017 |url=https://www.bbc.com/news/science-environment-42260580 |publisher=[[BBC News]] |access-date=7 December 2023 |archive-date=7 December 2023 |archive-url=https://web.archive.org/web/20231207201039/https://www.bbc.com/news/science-environment-42260580 |url-status=live }}</ref><ref name="Fretwell2013" /> 

Other major ice formations on land include [[ice cap]]s, [[ice field]]s, [[ice stream]]s and [[glacier]]s. In particular, the [[Hindu Kush]] region is known as the Earth's "Third Pole" due to the large number of glaciers it contains. They cover an area of around {{cvt|80,000|sqkm|sqmi}}, and have a combined volume of between 3,000-4,700&nbsp;km<sup>3</sup>.<ref name="HKH2019Cryo">{{Cite book |last1=Bolch |first1=Tobias |last2=Shea |first2=Joseph M. |last3=Liu |first3=Shiyin |last4=Azam |first4=Farooq M. |last5=Gao |first5=Yang |last6=Gruber |first6=Stephan |last7=Immerzeel |first7=Walter W. |last8=Kulkarni |first8=Anil |last9=Li |first9=Huilin |last10=Tahir |first10=Adnan A. |last11=Zhang |first11=Guoqing |last12=Zhang |first12=Yinsheng |title=The Hindu Kush Himalaya Assessment |date=5 January 2019 |chapter=Status and Change of the Cryosphere in the Extended Hindu Kush Himalaya Region |chapter-url=https://link.springer.com/chapter/10.1007/978-3-319-92288-1_7 |pages=209–255 |doi=10.1007/978-3-319-92288-1_7 |isbn=978-3-319-92287-4 |s2cid=134814572 }}</ref> These glaciers are nicknamed "Asian water towers", because their meltwater run-off feeds into rivers which provide water for an estimated two billion people.<ref name="HKH2019Water">{{Cite book |last1=Scott |first1=Christopher A. |last2=Zhang |first2=Fan |last3=Mukherji |first3=Aditi |last4=Immerzeel |first4=Walter |last5=Mustafa |first5=Daanish |last6=Bharati |first6=Luna |title=The Hindu Kush Himalaya Assessment |date=5 January 2019 |chapter=Water in the Hindu Kush Himalaya |chapter-url=https://link.springer.com/chapter/10.1007/978-3-319-92288-1_8 |pages=257–299 |doi=10.1007/978-3-319-92288-1_8 |isbn=978-3-319-92287-4 |s2cid=133800578 }}</ref>

[[Permafrost]] refers to [[soil]] or underwater [[sediment]] which continuously remains below {{cvt|0|C|F}} for two years or more.<ref>{{cite web |url=https://climate.mit.edu/explainers/permafrost |title=Permafrost |last1=McGee |first1=David |last2=Gribkoff |first2=Elizabeth |date=4 August 2022 |website=MIT Climate Portal |access-date=27 September 2023 }}</ref> The ice within permafrost is divided into four categories: pore ice, vein ice (also known as ice wedges), buried surface ice and intrasedimental ice (from the freezing of underground waters).<ref>{{Cite journal |last1=Lacelle |first1=Denis |last2=Fisher |first2=David A. |last3=Verret |first3=Marjolaine |last4=Pollard |first4=Wayne |date=17 February 2022 |title=Improved prediction of the vertical distribution of ground ice in Arctic-Antarctic permafrost sediments |journal=Communications Earth & Environment |volume=3 |issue=31 |page=31 |doi=10.1038/s43247-022-00367-z |bibcode=2022ComEE...3...31L |s2cid=246872753 }}</ref> One example of ice formation in permafrost areas is [[aufeis]] - layered ice that forms in Arctic and subarctic stream valleys. Ice, frozen in the stream bed, blocks normal groundwater discharge, and causes the local water table to rise, resulting in water discharge on top of the frozen layer. This water then freezes, causing the water table to rise further and repeat the cycle. The result is a stratified ice deposit, often several meters thick.<ref>{{Cite journal |last1=Huryn |first1=Alexander D. |last2=Gooseff |first2=Michael N. |last3=Hendrickson |first3=Patrick J. |last4=Briggs |first4=Martin A. |last5=Tape |first5=Ken D. |last6=Terry |first6=Neil C. |date=2020-10-13 |title=Aufeis fields as novel groundwater-dependent ecosystems in the arctic cryosphere |journal=Limnology and Oceanography |volume=66 |issue=3 |pages=607–624 |doi=10.1002/lno.11626 |s2cid=225139804 |issn=0024-3590|doi-access=free }}</ref> [[Snow line]] and [[snow field]]s are two related concepts, in that snow fields accumulate on top of and ablate away to the equilibrium point (the snow line) in an ice deposit.<ref>{{Cite book |last1=Johnson |first1=Chris |url=https://slcc.pressbooks.pub/introgeology/chapter/14-glaciers/ |title=An Introduction to Geology |last2=Affolter |first2=Matthew D. |last3=Inkenbrandt |first3=Paul |last4=Mosher |first4=Cam |date=July 1, 2017 |chapter=14 Glaciers}}</ref>