Editing Himalayas (section)

===Glaciers===
[[File:Annapurna I, south face.jpg|thumb|South Annapurna Glacier]]
The great ranges of central Asia, including the Himalayas, contain the third-largest deposit of ice and snow in the world, after [[Antarctica]] and the [[Arctic]].<ref name=pbs_nature/> Some even refer to this region as the "Third Pole".<ref name=":0">{{Cite journal |last1=Kulkarni |first1=Anil V. |last2=Karyakarte |first2=Yogesh |date=2014 |title=Observed changes in Himalayan Glaciers |url=https://www.jstor.org/stable/24099804 |journal=Current Science |volume=106 |issue=2 |pages=237–244 |jstor=24099804}}</ref> The Himalayan range encompasses about 15,000 glaciers, which store about {{convert|12000|km3|abbr=on}}, or 3600–4400 [[Gigatonne|Gt]] (10{{Superscript|12}} kg)<ref name=":0" /> of fresh water.<ref name=IPPC2007/> Its glaciers include the [[Gangotri Glacier|Gangotri]] and [[Yamunotri]] ([[Uttarakhand]]) and [[Khumbu Glacier|Khumbu]] glaciers ([[Mount Everest]] region), [[Langtang]] glacier ([[Langtang]] region), and [[Zemu Glacier|Zemu]] ([[Sikkim]]).

Owing to the mountains' latitude near the [[Tropic of Cancer]], the permanent [[snow line]] is among the highest in the world, at typically around {{convert|5500|m|abbr=on|-2}}.<ref>{{cite journal|last1=Shi |first1=Yafeng |last2=Xie |first2=Zizhu |last3=Zheng |first3=Benxing |last4=Li |first4=Qichun |url=http://itia.ntua.gr/hsj/redbooks/126/iahs_126_0111.pdf |archive-url=https://web.archive.org/web/20130424125203/http://itia.ntua.gr/hsj/redbooks/126/iahs_126_0111.pdf |archive-date=24 April 2013 |title=Distribution, Feature and Variations of Glaciers in China |journal=World Glacier Inventory |year=1978 |url-status=dead }}</ref> In contrast, equatorial mountains in [[New Guinea]], the [[Rwenzoris]], and [[Colombia]] have a snow line some {{convert|900|m|abbr=on|-1}} lower.<ref>{{cite book|last1=Henderson-Sellers|first1=Ann|last2=McGuffie|first2=Kendal|title=The Future of the World's Climate: A Modelling Perspective|pages=199–201|isbn=978-0-12-386917-3|year=2012|publisher=Elsevier }}</ref> The higher regions of the Himalayas are snowbound throughout the year, in spite of their proximity to the tropics, and they form the sources of several large [[perennial stream|perennial rivers]].
[[File:KhumbuIcefall.jpg|thumb|left|[[Icefall]] on [[Khumbu Glacier]]]]
In recent years, scientists have monitored a notable increase in the rate of [[Retreat of glaciers since 1850|glacier retreat]] across the region as a result of climate change.<ref>{{Cite journal|last1=Lee|first1=Ethan|last2=Carrivick|first2=Jonathan L.|last3=Quincey|first3=Duncan J.|last4=Cook|first4=Simon J.|last5=James|first5=William H. M.|last6=Brown|first6=Lee E.|date=2021-12-20|title=Accelerated mass loss of Himalayan glaciers since the Little Ice Age|journal=Scientific Reports|language=en|volume=11|issue=1|pages=24284|doi=10.1038/s41598-021-03805-8|issn=2045-2322|pmc=8688493|pmid=34931039| bibcode=2021NatSR..1124284L }}</ref><ref>{{cite news|url=https://www.reuters.com/article/environment-nepal-climate-glaciers-dc/vanishing-himalayan-glaciers-threaten-a-billion-idUSDEL18761020070604|title=Vanishing Himalayan Glaciers Threaten a Billion|date=4 June 2007|newspaper=Reuters |access-date=13 March 2018}}</ref> For example, glacial lakes have been forming rapidly on the surface of debris-covered glaciers in the Bhutan Himalaya during the last few decades. Studies have measured an approximately 13% overall decrease in glacial coverage in the Himalayas over the last 40–50 years.<ref name=":0" /> Local conditions play a large role in glacial retreat, however, and glacial loss can vary locally from a few m/yr to 61 m/yr.<ref name=":0" /> A marked acceleration in glacial mass loss has also been observed since 1975, from about 5–13 Gt/yr to 16–24 Gt/yr.<ref name=":0" /> Although the effect of this will not be known for many years, it potentially could mean disaster for the hundreds of millions of people who rely on the glaciers to feed the rivers during the dry seasons.<ref name=":0" /><ref>{{Cite journal|last1=Kaushik|first1=Saurabh|last2=Rafiq|first2=Mohammd|last3=Joshi|first3=P.K.|last4=Singh|first4=Tejpal|date=April 2020|title=Examining the glacial lake dynamics in a warming climate and GLOF modelling in parts of Chandra basin, Himachal Pradesh, India|journal=Science of the Total Environment|language=en|volume=714|pages=136455|doi=10.1016/j.scitotenv.2019.136455|pmid=31986382|bibcode=2020ScTEn.71436455K|s2cid=210933887}}</ref><ref>{{Cite journal|last1=Rafiq|first1=Mohammd|last2=Romshoo|first2=Shakil Ahmad|last3=Mishra|first3=Anoop Kumar|last4=Jalal|first4=Faizan|date=January 2019|title=Modelling Chorabari Lake outburst flood, Kedarnath, India|url=http://link.springer.com/10.1007/s11629-018-4972-8|journal=Journal of Mountain Science|language=en|volume=16|issue=1|pages=64–76|doi=10.1007/s11629-018-4972-8|bibcode=2019JMouS..16...64R |s2cid=134015944|issn=1672-6316}}</ref><ref>{{cite web|url=http://en.people.cn/90001/90781/90879/6222327.html|title=Glaciers melting at alarming speed|date=24 July 2007|publisher=People's Daily Online|access-date=17 April 2009|archive-date=11 October 2017|archive-url=https://web.archive.org/web/20171011182931/http://en.people.cn/90001/90781/90879/6222327.html|url-status=dead}}</ref> The global climate change will affect the water resources and livelihoods of the Greater Himalayan region.<ref>{{Cite book |url=http://www.nap.edu/catalog/13449 |title=Himalayan Glaciers: Climate Change, Water Resources, and Water Security |date=2012|publisher=National Academies Press |isbn=978-0-309-26098-5 |location=Washington, D.C.|doi=10.17226/13449 }}</ref>