Editing Mount Ruapehu (section)

===Glaciers===

A total of 18 [[glacier]]s have been recognised on Ruapehu, of which six are named.<ref name="Chinn 2001">{{cite journal |last1=Chinn |first1=T. J. |title=Distribution of the Glacial Water Resources of New Zealand |journal=Journal of Hydrology (New Zealand) |date=2001 |volume=40 |issue=2 |pages=139–187 |jstor=43922047 |url=https://www.jstor.org/stable/43922047 |access-date=2 February 2021 |archive-date=30 October 2020 |archive-url=https://web.archive.org/web/20201030001642/https://www.jstor.org/stable/43922047 |url-status=live }}</ref> Two glaciers are found in the active crater: one on the north side of the crater under Paretetaitonga Peak and another one to the south, and these are New Zealand's only crater glaciers.<ref name="Keys 1988" /> Most of the ice on Ruapehu is contained in only three of its glaciers: the Whangaehu, Summit Plateau, and Mangatoetoenui glaciers.<ref name="Chinn 2001" /> The Summit Plateau glacier is not a glacier in the true sense, but rather an ice field that fills an extinct volcanic crater, and the ice there reaches more than 130&nbsp;m thick.<ref name="Keys 1988" /> The Whangaehu glacier feeds the Whangaehu River, and the Mangatoetoenui glacier is one of the principal sources of the [[Waikato River]], which arises as a series of streams on Ruapehu's eastern slopes.<ref name="Keys 1988" /><ref name="Miles 1984">{{cite book |last1=Miles |first1=Sue |title=The River : the story of the Waikato |date=1984 |publisher=Heinemann |location=Auckland, N.Z. |isbn=978-0-86863-418-0}}</ref> On the western side of the mountain, many of the streams that arise there, such as the [[Whakapapa River|Whakapapa]] and [[Manganui o te Ao River|Manganui o te Ao]] rivers, feed the [[Whanganui River]].<ref>{{cite map |author=Land Information New Zealand |author-link=Land Information New Zealand |year=2020 |title=NZ Topo50 |type=Topographic map |scale=1:50,000 |publisher=Land Information New Zealand}}</ref>

[[File:MountRuapehu.jpg|thumb|300px|Mount Ruapehu, January 2002.]]
Ruapehu's glaciers are situated at the northern limit for the formation of permanent ice in New Zealand, and thus they are extremely sensitive to changes in climate. Surveys of the glaciers undertaken since 1955 have found that the glaciers have all been thinning and retreating, with the exception of the northern crater glacier, which thickened and lengthened after the 1953 outburst of Crater Lake lowered the lake water level.<ref name="Keys 1988">{{cite journal |last1=Keys |first1=H. |title=1988 Survey of the Glaciers on Mt Ruapehu, Tongariro National Park – A Baseline for Detecting Threats of Climate Change |journal=Department of Conservation Science and Research Internal Report 24 (Unpublished) |date=1988 |url=https://www.doc.govt.nz/globalassets/documents/science-and-technical/srir24.pdf |access-date=2 February 2021 |archive-date=25 October 2021 |archive-url=https://web.archive.org/web/20211025071106/https://www.doc.govt.nz/globalassets/documents/science-and-technical/srir24.pdf |url-status=live }}</ref><ref name="Odell 1955">{{cite journal |last1=Odell |first1=N. E. |title=Mount Ruapehu, New Zealand: Observations on its Crater Lake and Glaciers |journal=Journal of Glaciology |date=1955 |volume=2 |issue=18 |pages=601–605 |doi=10.3189/002214355793702181|bibcode=1955JGlac...2..601O |doi-access=free}}</ref>