Mount Everest
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Ggonnell
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{{Infobox Mountain
| Name = Mount Everest
| Photo = Everest kalapatthar crop.jpg
| Caption = Everest from [[Kala Patthar]] in Nepal
|pushpin_map = Nepal
|pushpin_label_position =bottom <!-- the position of the pushpin label: left, right, top, bottom, none -->
|pushpin_map_caption =Location within Nepal on the Nepal-Tibet border
|pushpin_mapsize =325
|coordinates_ref= <ref>The [[WGS84]] coordinates given here were calculated using detailed topographic mapping and are in agreement with [http://www.adventurestats.com/tables/8000erbasics.htm adventurestats]. They are unlikely to be in error by more than 2". Coordinates showing Everest to be more than a minute further east that appeared on this page until recently, and still appear in Wikipedia in several other languages, are incorrect.</ref>
|latd=27 |latm=59 |lats=17 |latNS=N
|longd=86 |longm=55 |longs=31 |longEW=E
| Elevation = {{convert|8848|m|ft|0}}<!-- This elevation, and the reasons for supporting it, are laid out and referenced in the measurement section, but some editors believe we should support 8844 m or 8850 m instead. If any editor thinks we should change it, could he/she please make the case on the talk page and allow time for discussion before editing. --><ref>Based on elevation of snow cap, not rock head. For more details, see ''[[#Measurement|Measurement]]''.</ref> <br /><small> [[Eight-thousander|Ranked 1st]]</small>
| Location = {{flagicon|NEP}} [[Sagarmatha Zone]], [[Nepal]]<br>{{flagicon|PRC}} [[Tibet]], [[China]]<ref>The position of the summit of Everest on the international border is clearly shown on detailed topographic mapping, including official Nepalese mapping.</ref>
| Range = [[Mahalangur Himal]], [[Himalaya]]
| Prominence = {{convert|8848|m|ft|0|abbr=on}}
| First ascent = [[May 29]], [[1953]]<br>{{flagicon|NZL}} [[Edmund Hillary]]<br>{{flagicon|NEP}} [[Tenzing Norgay]]
| Without oxygen bottles = 1978, by [[Reinhold Messner]] and [[Peter Habeler]]
| Solo ascent = 1980, by Reinhold Messner
| Easiest route = [[South Col]] (Nepal)
}}
{{Location map
|Earth|
|lat_deg=27|lat_min=59|lat_sec=17
|lon_deg=86|lon_min=55|lon_sec=31
|position=left
|width=400
|float=right
|caption=Location on Earth
}}
[[Image:MountEverestRelief.png|thumb|305px|Mount Everest [[Cartographic relief depiction|relief map]]]]
'''Mount Everest''', also called '''Chomolungma''', '''Qomolangma''' or '''Zhumulangma''' (in {{lang-bo|ཇོ་མོ་གླང་མ}}, in [[Standard Mandarin|Chinese]]: 珠穆朗玛峰 ''Zhūmùlǎngmǎ Fēng'') or '''Sagarmatha''' ({{lang-ne|सगरमाथा}}'' meaning Ocean Head'') is the [[Extremes of Altitude|highest mountain]] on [[Earth]], as measured by the height of its [[Topographical summit|summit]] above [[sea level]], which is 8,848 metres (29,029 feet). The mountain, which is part of the [[Himalaya]] range in High Asia, is located on the border between [[Sagarmatha Zone]], [[Nepal]], and [[Tibet]], [[China]].
In [[1856]], the [[Great Trigonometric Survey]] of India established the first published height of Everest at {{convert|29002|ft|m|0|abbr=on}}, although at the time Everest was known as '''Peak XV'''. In [[1865]], Everest was given its official English name by the [[Royal Geographical Society]] upon recommendation of [[Andrew Scott Waugh|Andrew Waugh]], the [[United Kingdom|British]] [[:Category:Surveyors General of India|Surveyor General of India]] at the time. Waugh was unable to propose an established local name due to Nepal and Tibet being closed to foreigners at the time, although Chomolungma had been in common use by Tibetans for centuries.
The highest mountain in the world attracts climbers of all levels, from well experienced mountaineers to novice climbers willing to pay substantial sums to professional mountain guides to complete a successful climb. The mountain, while not posing substantial technical climbing difficulty on the standard route (other [[eight-thousander]]s such as [[K2]] or [[Nanga Parbat]] are much more difficult), still has many inherent dangers such as altitude sickness, weather and wind. By the end of the [[2007]] climbing season, there had been 3,679 ascents to the summit by 2,436 individuals. This means climbers are a significant source of [[tourist]] revenue for Nepal, whose government also requires all prospective climbers to obtain an expensive permit, costing up to [[United States dollar|US$]]25,000 per person.<ref>{{cite web |url=http://www.nationalgeographic.com/adventure/0305/expert_everest.html |title=National Geographic Adventure Magazine: Ask Adventure--Tips |accessdate=2008-01-23}}</ref> Everest has claimed 210 lives, including 15 who perished during a 1996 storm high on the mountain. Conditions are so difficult in the [[death zone]] that most corpses have been left where they fell, some of which are visible from standard climbing routes.<ref>{{cite web |url=http://www.education.theage.com.au/pagedetail.asp?intpageid=1652&strsection=students&intsectionid=0 |title= Ethics of Everest |accessdate=2008-01-23 |work=The Age Education}}</ref>
==Discovery of the highest mountain ==
In [[1808]], the British began the [[Great Trigonometric Survey]] of India to determine the location and names of the world's highest mountains. Starting in southern India, the survey teams gradually moved northward using giant 1100 pound (500 kg) [[theodolite]]s (each requiring 12 men to carry) to measure heights as accurately as possible. They reached the Himalayan foothills by the [[1830s]], but Nepal was unwilling to allow the British to enter the country due to suspicions of political aggression and possible annexation. Several requests by the surveyors to enter Nepal were turned down.
The British were forced to continue their observations from [[Terai]], a region south of Nepal which is parallel to the Himalayas. Conditions in Terai were difficult due to torrential rains and [[malaria]] — three survey officers died from malaria while two others had to retire due to failing health.
Nonetheless, in [[1847]], the British pressed on and began detailed observations of the Himalayan peaks from observation stations up to {{convert|150|mi|km|abbr=on}} away. Weather restricted work to the last three months of the year. In [[November]] [[1847]], [[Andrew Scott Waugh|Andrew Waugh]], the [[United Kingdom|British]] [[:Category:Surveyors General of India|Surveyor General of India]] made a number of observations from [[Sawajpore]] station located in the eastern end of the Himalayas. At the time, [[Kangchenjunga]] was considered the highest peak in the world, and with interest he noted a peak beyond it, some {{convert|140|mi|km|abbr=on}} away. John Armstrong, one of Waugh's officials, also saw the peak from a location further west and called it peak 'b'. Waugh would later write that the observations indicated that peak 'b' was higher than Kangchenjunga, but due to the great distance of the observations, closer observations were required for verification. The following year, Waugh sent a survey official back to Terai to make closer observations of peak 'b', but clouds thwarted all attempts.
In [[1849]], Waugh dispatched James Nicolson to the area. Nicolson was able to make two observations from [[Jirol]], {{convert|118|mi|km|abbr=on}} away. Nicolson then took the largest theodolite and headed east, obtaining over 30 observations from five different locations, with the closest being {{convert|108|mi|km|abbr=on}} away from the peak. <ref name=everest_bwp70>{{cite book |title= Everest - The Best Writing and Pictures from Seventy Years of Human Endeavour |editor=Peter Gillman| year=1993 |publisher=Little, Brown and Company|location= |isbn=0-316-90489-3 |pages=pp.10-13}}</ref>
Nicolson retreated to [[Patna]] on the [[Ganges]] to perform the necessary calculations based on his observations. His raw data gave an average height of {{convert|30200|ft|m|abbr=on}} for peak 'b', but this did not take into account [[light refraction]] which distorts heights. The number clearly indicated, however, that peak 'b' was higher than Kangchenjunga. Unfortunately, Nicolson came down with malaria and was forced to return home, calculations unfinished. Michael Hennessy, one of Waugh's assistants, had begun designating peaks based on [[Roman Numerals]], with Kangchenjunga named Peak IX, while peak 'b' now became known as Peak XV.<ref name=everest_bwp70/>
In [[1852]], stationed at the survey's headquarters in [[Dehradun]], [[Radhanath Sikdar]], an Indian mathematician and surveyor from [[Bengal]], was the first to identify Everest as the world's highest peak, using [[trigonometry|trigonometric]] calculations based on Nicolson's measurements.<ref name=BBC_mwde>[http://news.bbc.co.uk/2/hi/south_asia/3193576.stm The man who 'discovered' Everest] BBC News</ref> An official announcement that Peak XV was the highest was delayed for several years as the calculations were repeatedly verified. Waugh began work on Nicolson's data in 1854, and along with his staff spent almost two years working on the calculations, having to deal with the problems of light refraction, barometric pressure, and temperature over the vast distances of the observations. Finally, in March 1856 he announced his findings in a letter to his deputy in [[Kolkata|Calcutta]]. Kangchenjunga was declared to be {{convert|28156|ft|m|0|abbr=on}}, while Peak XV was given the height of {{convert|29002|ft|m|0|abbr=on}}. Waugh concluded that Peak XV was "most probably the highest in the world".<ref name=everest_bwp70/> Peak XV was found to be exactly {{convert|29000|ft|m|0}} high, but was publicly declared to be {{convert|29002|ft|m|0|abbr=on}}. The arbitrary addition of 2 feet (60 cm) was to avoid the impression that an exact height of 29,000 feet was nothing more than a rounded estimate.<ref name=tas1982>Letters to the Editor, ''The American Statistician'', Vol. 36, No. 1 (Feb., 1982), pp. 64-67 [http://www.jstor.org/pss/2684102 JSTOR]</ref>
With the height now established, what to name the peak was clearly the next challenge. While the survey was anxious to preserve local names if possible (e.g., Kangchenjunga and [[Dhaulagiri]] were local names), Waugh argued that he was unable to find any commonly used local name. Waugh's search for a local name was hampered by Nepal and Tibet being closed to foreigners at the time. Many local names existed, with perhaps the best known in Tibet for several centuries being Chomolungma, which had appeared on a 1733 map published in Paris by the French geographer [[Jean Baptiste Bourguignon d'Anville|D'Anville]]. However, Waugh argued that with the plethora of local names, it would be difficult to favour one specific name over all others. So, he decided that Peak XV should be named after [[George Everest]], his predecessor as Surveyor General of India.<ref name=everest_bwp70/> He wrote:
<blockquote>
I was taught by my respected chief and predecessor, Colonel Sir George Everest to assign to every geographical object its true local or native appellation. But here is a mountain, most probably the highest in the world, without any local name that we can discover, whose native appellation, if it has any, will not very likely be ascertained before we are allowed to penetrate into Nepal. In the meantime the privilege as well as the duty devolves on me to assign…a name whereby it may be known among citizens and geographers and become a household word among civilized nations.<ref name=rgs1857>"Papers relating to the Himalaya and Mount Everest", ''Proceedings of the Royal Geographical Society of London'', no.IX pp.345-351, April-May 1857.</ref>
</blockquote>
George Everest opposed the name suggested by Waugh and told the [[Royal Geographical Society]] in 1857 that Everest could not be written in [[Hindi]] nor pronounced by "the native of India". Waugh's proposed name prevailed despite the objections, and in 1865, the Royal Geographical Society officially adopted Mount Everest as the name for the highest mountain in the world.<ref name=everest_bwp70/>
== Naming ==
[[Image:102 0245eve.jpg|thumb|centre|640px|Aerial view of Mount Everest from the south]]
The [[Tibetan language|Tibetan]] name for Mount Everest is '''Chomolungma''' or '''Qomolangma''' ({{unicode|ཇོ་མོ་གླིང་མ}}, which means "[[Saint]] Mother"), and the [[Chinese language|Chinese]] transliteration is '''{{unicode|Zhūmùlǎngmǎ Fēng}}''' ({{zh-st|s=珠穆朗玛峰|t=珠穆朗瑪峰}}); the Chinese translation is '''Shèngmǔ Fēng''' ({{zh-st|s=圣母峰|t=聖母峰}}), but this name is seldom used. According to English accounts of the [[19th century|mid-19th century]], the local name in [[Darjeeling]] for Mount Everest was ''Deodungha'', or "Holy Mountain".<ref>{{cite web |url=http://www.harappa.com/engr/darjeeling.html#everest |title=Mt. Everest 1857 |accessdate=2008-01-23 |work=harappa.com}}</ref>
In [[1865]], the mountain was officially given its [[English language|English]] name by the Royal Geographical Society after being proposed by [[Andrew Scott Waugh|Andrew Waugh]], the [[United Kingdom|British]] [[:Category:Surveyors General of India|Surveyor General of India]].<ref name=everest_bwp70/> Waugh chose to name the mountain after [[George Everest]], first using the spelling '''Mont Everest''', and then '''Mount Everest'''. However, the modern pronunciation of Everest {{IPAEng|ˈɛvərɪst, ˈɛvrɪst}}<ref>[http://dictionary.reference.com/browse/Everest%2C%20Mount?r=14 Everest, Mount - Definitions from Dictionary.com] (Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006)</ref> is in fact different from Sir George's own pronunciation of his surname, which was {{IPA|/ˈiːvrɪst/}}<ref>{{cite video | people = Claypole, Jonty (Director); Kunzru, Hari (Presenter) | url = http://www.bbc.co.uk/programmes/b0074phg | title = Mapping Everest | medium = TV Documentary | publisher = BBC Television | location = London | year2 = 2003 }}</ref>.
In the late 19th century, many European [[cartography|cartographers]] incorrectly believed that a native name for the mountain was "Gaurisankar".<ref name="waddell">L. A. Waddell, "The Environs and Native Names of Mount Everest," ''The Geographical Journal'', Vol. 12, No. 6 (Dec. 1898), pp. 564-569. Available at [http://links.jstor.org/sici?sici=0016-7398(189812)12%3A6%3C564%3ATEANNO%3E2.0.CO%3B2-A JSTOR].</ref> This was a result of confusion of Mount Everest with the actual [[Gauri Sankar]], which, when viewed from [[Kathmandu]], stands almost directly in front of Everest. {{Fact|date=December 2007}}
In the early [[1960s]], the [[Nepal|Nepalese government]] gave Mount Everest the official name '''Sagarmatha''' (सगरमाथा).<ref name="Unsworth584">{{cite book |title= Everest - The Mountaineering History |last=Unsworth |first=Walt |authorlink= |coauthors= |year=2000 |publisher=Bâton Wicks|location= |isbn=978-1898573401 |pages=p.584|edition=3rd edition}}</ref> This name had not previously been used; the local inhabitants knew the mountain as ''Chomolungma''. The mountain was not known and named in ethnic Nepal (that is, the [[Kathmandu valley]] and surrounding areas). {{Fact|date=December 2007}} The government set out to find a Nepalese name for the mountain because the [[Sherpa]]/Tibetan name ''Chomolangma'' was not acceptable, as it would have been against the idea of unification (Nepalization) of the country.{{Fact|date=December 2007}}
In [[2002]], the Chinese ''[[People's Daily]]'' newspaper published an article making a case against the continued use of the English name for the mountain in the [[Western world]], insisting that it should be referred to by its Tibetan name. The newspaper argued that the Chinese (in nature a Tibetan) name preceded the English one, as Mount Qomolangma was marked on a Chinese map more than 280 years ago.<ref>{{cite web|url=http://english.people.com.cn/200211/19/eng20021119_107017.shtml|title=Web Reference|accessdate=2007-04-01}}</ref>
== Measurement ==
[[Image:Mount Everest North Face.jpg|thumb|320px|Mount Everest north face from Rongbuk in Tibet]]
[[Image:Mt Everest Aerial.jpg|thumb|320px|Another aerial view of Mount Everest from the south, with Lhotse in front and Nuptse on the left]]
In 1856, Andrew Waugh announced Everest (then known as Peak XV) as {{convert|29002|ft|m|0}} high, after several years of calculations based on observations made by the [[Great Trigonometric Survey]].
More recently, the mountain has been found to be {{convert|8848|m|ft|0}} high, although there is some variation in the measurements. On [[22 May]] [[2005]], the People's Republic of China's Everest Expedition Team ascended to the top of the mountain. On [[9 October]] [[2005]], after several months of measurement and calculation, the PRC's State Bureau of Surveying and Mapping officially announced the height of Everest as 8,844.43 m ± 0.21 m (29,017.16 ± 0.69 [[foot (unit of length)|ft]]). They claimed it was the most accurate and precise measurement to date.<ref>{{cite web|url=http://news.xinhuanet.com/english/2005-10/09/content_3597013.htm |title=Xinhua.net |accessdate=2007-04-01}}</ref> This height is based on the actual highest point of rock and not on the snow and ice covering it. The Chinese team also measured a snow/ice depth of 3.5 m,<ref>{{cite web |url=http://www.abc.net.au/science/news/enviro/EnviroRepublish_1478658.htm |title=abc.au article |accessdate=2007-04-01}}</ref> which is in agreement with a net elevation of 8,848 m. The snow and ice thickness varies over time, making a definitive height of the snow cap impossible to determine.
The elevation of {{convert|8848|m|ft|0|abbr=on}} was first determined by an Indian survey in 1955, made closer to the mountain, also using [[theodolite]]s. It was subsequently reaffirmed by a 1975 Chinese measurement.<ref>{{cite web|url=http://www.abc.net.au/science/news/enviro/EnviroRepublish_1478658.htm|title=ABC.net|accessdate=2007-04-01}}</ref> In both cases the snow cap, not the rock head, was measured. In May 1999 an American Everest Expedition, directed by [[Bradford Washburn]], anchored a [[Global Positioning System|GPS]] unit into the highest bedrock. A rock head elevation of 8,850 m (29,035 ft), and a snow/ice elevation 1 m (3 ft) higher, were obtained via this device.<ref name="alpres">{{cite web|url=http://www.alpineresearch.ch/alpine/en/presse1.html|title=Alpine Research|accessdate=2007-04-01}}</ref> Although it has not been officially recognized by Nepal,<ref>{{cite web|url=http://www.nepalgov.gov.np/countryprofile.php|title=Nepalese government site|accessdate=2007-04-01}}</ref> this figure is widely quoted. [[Geoid]] uncertainty casts doubt upon the accuracy claimed by both the 1999 and 2005 surveys.
A detailed [[photogrammetry|photogrammetric]] map (at a scale of 1:50,000) of the [[Khumbu]] region, including the south side of Mount Everest, was made by Erwin Schneider as part of the 1955 International Himalayan Expedition, which also attempted [[Lhotse]]. An even more detailed [[topography|topographic]] map of the Everest area was made in the late 1980s under the direction of Bradford Washburn, using extensive [[aerial photography]].<ref name="washburn_map"/>
It is thought that the [[plate tectonics]] of the area are adding to the height and moving the summit north-eastwards. Two accounts<ref name="alpres">{{cite web|url=http://www.alpineresearch.ch/alpine/en/presse1.html|title=www.alpineresearch.ch/alpine/en/presse1.html<!--INSERT TITLE-->|accessdate=2007-04-01}}</ref><ref>{{cite web|url=http://www.nationalgeographic.com/features/99/everest/roof_content.html|title=National Geographic|accessdate=2007-04-01}}</ref> suggest the rates of change are {{convert|4|mm|in|abbr=on|lk=on}} per year (upwards) and 3-6 mm (0.12-0.25 in) per year (northeastwards), but another account mentions more lateral movement ({{convert|27|mm|in|abbr=on|disp=/}}),<ref>{{cite web|url=http://www.mos.org/Everest/exhibit/platetectonics.htm|title=Museum of Science|accessdate=2007-04-01}}
{{waybackdate|site=http://www.mos.org/Everest/exhibit/platetectonics.htm|date=20060517225040|title=Now hosted at the Internet Archive}}</ref>
and even shrinkage has been suggested.<ref>{{cite web|url=http://news.bbc.co.uk/1/hi/world/asia-pacific/4204539.stm|title=BBC News|accessdate=2007-04-01}}</ref>
The Mount Everest region, and the [[Himalayas]] in general, are thought to be experiencing ice-melt due to [[global warming]].<ref>{{cite web|url=http://news.bbc.co.uk/2/hi/south_asia/6201399.stm|title=India and China in warming study|accessdate=2007-04-01}}</ref>
===Comparisons===
Everest is the mountain whose summit attains the greatest distance above [[sea level]]. Several other mountains are sometimes claimed as alternative "tallest mountains on Earth". [[Mauna Kea]] in [[Hawaii]] is tallest when measured from its base;<ref name="base">The "base" of a mountain is a problematic notion in general with no universally accepted definition. However for a peak rising out of relatively flat terrain, such as Mauna Kea or Denali, an ''approximate'' height above "base" can be calculated. For Everest the situation is more complicated, since it only rises above relatively flat terrain on its north (Tibetan Plateau) side. Hence the concept of "base" has even less meaning for Everest than for Mauna Kea or Denali, and the range of numbers for "height above base" is wider. In general, comparisons based on "height above base" are somewhat suspect.</ref> it rises over {{convert|10200|m|mi|1|abbr=on}} when measured from its base on the mid-ocean floor, but only attains {{convert|4205|m|ft|0|abbr=on}} above sea level.
By the same measure of base<ref name="base"/> to summit, [[Mount McKinley|Denali]], in [[Alaska]], is also taller than Everest. Despite its height above sea level of only {{convert|6193.6|m|ft|0|abbr=on}}, Denali sits atop a sloping plain with elevations from 300-900 m (1,000-3,000 ft), yielding a height above base in the range of 5,300-5,900 m (17,300-19,300 ft); a commonly quoted figure is {{convert|5600|m|ft|-2|abbr=on}}.<ref>{{cite web|url=http://www.pbs.org/wgbh/nova/denali/expedition/mission.html|title=NOVA Online: Surviving Denali, The Mission|accessdate=2007-06-07}}</ref> By comparison, reasonable base elevations for Everest range from {{convert|4200|m|ft|-2|abbr=on}} on the south side to {{convert|5200|m|ft|-2|abbr=on}} on the [[Tibetan Plateau]], yielding a height above base in the range of 3,650 m (12,000 ft) to 4,650 m (15,300 ft).<ref name="washburn_map">''Mount Everest'' (1:50,000 scale map), prepared under the direction of [[Bradford Washburn]] for the Boston Museum of Science, the Swiss Foundation for Alpine Research, and the [[National Geographic Society]], 1991, ISBN 3-85515-105-9</ref>
The summit of [[Chimborazo (volcano)|Chimborazo]] in [[Ecuador]] is {{convert|2168|m|ft|0|abbr=on}} farther from the Earth's centre (6,384.4 km or 3,967.1 [[mile|mi]]) than that of Everest (6,382.3 km or 3,965.8 mi), because the Earth bulges at the Equator. However, Chimborazo attains a height of only {{convert|6267|m|ft|0|abbr=on}} above sea level, and by this criterion it is not even the highest peak of the [[Andes]].
Measured from sea level, the mountain [[K2]] is ranked second in height with {{convert|8611|m|ft|0|abbr=on}} high.
The deepest spot in the ocean is deeper than Everest is high: the [[Challenger Deep]], off the [[Mariana Islands]], is so deep that if Everest could be placed into it there would be more than 2 km (more than 1.3 mi) of water covering it.
== Climbing routes ==
<!-- The image map below was added in Sept 07 - see discussion page -->
<imagemap>
Image:Himalaya_annotated.jpg|thumb|250px|left|Southern and northern climbing routes as seen from the International Space Station.
rect 58 14 160 49 [[Chomo Lonzo]]
rect 200 28 335 52 [[Makalu]]
rect 378 24 566 45 [[Mount Everest]]
rect 188 581 920 656 [[Tibetan Plateau]]
rect 250 406 340 427 [[Rong River]]
rect 333 149 409 186 [[Changtse]]
rect 550 284 677 303 [[Rongbuk Glacier]]
rect 478 196 570 218 [[Mount Everest|North Face]]
rect 237 231 346 267 [[East Rongbuk Glacier]]
rect 314 290 536 309 [[Mount Everest|North Col north ridge route]]
rect 531 79 663 105 [[Lhotse]]
rect 582 112 711 130 [[Nuptse]]
rect 603 232 733 254 [[South Col|South Col route]]
rect 716 165 839 206 [[Gyachung Kang]]
rect 882 147 967 183 [[Cho Oyu]]
rect 1 1 999 661 [[Image:Himalaya_annotated.jpg]]
desc bottom-left
</imagemap>
Mt. Everest has two main climbing routes, the southeast ridge from Nepal and the northeast ridge from [[Tibet]], as well as many other less frequently climbed routes.<ref name=evhist>{{cite web |url=http://www.everesthistory.com/routes.htm |title=EverestHistory.com: Ascent Routes on Everest |accessdate=2008-01-23}}</ref> Of the two main routes, the southeast ridge is technically easier and is the more frequently-used route. It was the route used by [[Edmund Hillary]] and [[Tenzing Norgay]] in 1953 and the first recognised of fifteen routes to the top by 1996.<ref name=evhist/> This was, however, a route decision dictated more by politics than by design as the Chinese border was closed to western world in 1950s after the [[People's Republic of China|Communist China]] took over the control Tibet from the [[Republic of China]].<ref name=ngetl>{{cite web|author=National Geographic| url=http://news.nationalgeographic.com//news/2003/04/0401_030401_everesttimeline.html| title=Everest Time Line: 80 Years of Triumph and Tragedy| last=Thompson|first=Kalee|date=2003-04-02|accessdate=2008-03-28}}</ref>
[[Image:STS058-101-12 2.JPG|thumb|250px|View from space showing South Col route and North Col/Ridge route]]
Most attempts are made during May before the summer [[monsoon]] season. As the monsoon season approaches, a change in the [[jet stream]] at this time pushes it northward, thereby reducing the average wind speeds high on the mountain.<ref name=nytimes>{{cite web|author=NY Times| url=http://query.nytimes.com/gst/fullpage.html?res=9E01EFDD1E38F93AA25756C0A961958260|title= Climbing Mount Everest}}</ref><ref name=te03>{{cite web|author=Team Everest 03|url=http://www.teameverest03.org/everest_info/index.html|title=Mt. Everest Information}}</ref> While attempts are sometimes made after the monsoons in September and October, when the jet stream is again temporarily pushed northward, the additional snow deposited by the monsoons and the less stable weather patterns (tail end of the monsoon) makes climbing more difficult.
=== Southeast ridge ===
The ascent via the southeast ridge begins with a trek to [[Everest Base Camp|Base Camp]] at {{convert|5380|m|ft|-2|abbr=on}} on the south side of Everest in Nepal. Expeditions usually fly into [[Lukla]] (2,860 m) from [[Kathmandu]] and pass through [[Namche Bazaar]]. Climbers then hike to Base Camp, which usually takes six to eight days, allowing for proper altitude acclimatization in order to prevent [[altitude sickness]]. Climbing equipment and supplies are carried by [[yak]]s, [[dzo]]pkyos (yak hybrids) and human [[Porter (carrying)|porters]] to Base Camp on the [[Khumbu Glacier]]. When Hillary and Tenzing climbed Everest in 1953, they started from Kathmandu Valley, as there were no roads further east at that time.
Climbers will spend a couple of weeks in Base Camp, acclimatizing to the altitude. During that time, [[Sherpa (people)|Sherpas]] and some expedition climbers will set up ropes and ladders in the treacherous [[Khumbu Icefall]]. [[Serac]]s, crevasses and shifting blocks of ice make the icefall one of the most dangerous sections of the route. Many climbers and Sherpas have been killed in this section. To reduce the hazard, climbers will usually begin their ascent well before dawn when the freezing temperatures glue ice blocks in place. Above the icefall is Camp I at {{convert|6065|m|ft|-1}}.
From Camp I, climbers make their way up the [[Western Cwm]] to the base of the [[Lhotse]] face, where Camp II or Advanced Base Camp (ABC) is established at {{convert|6500|m|ft|-2|abbr=on}}. The Western Cwm is a relatively flat, gently rising glacial valley, marked by huge lateral [[crevasse]]s in the centre which prevent direct access to the upper reaches of the Cwm. Climbers are forced to cross on the far right near the base of [[Nuptse]] to a small passageway known as the "Nuptse corner". The Western Cwm is also called the "Valley of Silence" as the topography of the area generally cuts off wind from the climbing route. The [[high altitude]] and a clear, windless day can make the Western Cwm unbearably hot for climbers.<ref name=nova-climb>[http://www.pbs.org/wgbh/nova/everest/climb/waytosummitsou.html The Way to the Summit]</ref>
From ABC, climbers ascend the Lhotse face on [[fixed rope]]s up to Camp III, located on a small ledge at {{convert|7470|m|ft|-2|abbr=on}}. From there, it is another 500 metres to Camp IV on the [[South Col]] at {{convert|7920|m|ft|-2|abbr=on}}. From Camp III to Camp IV, climbers are faced with two additional challenges: The Geneva Spur and The Yellow Band. The Geneva Spur is an anvil shaped rib of black rock named by a 1952 Swiss expedition. Fixed ropes assist climbers in [[scrambling]] over this snow covered rock band. The Yellow Band is a section of interlayered [[marble]], [[phyllite]], and [[schist|semischist]] which also requires about 100 metres of rope for traversing it.<ref name=nova-climb/>
On the South Col, climbers enter the [[death zone]]. Climbers typically only have a maximum of two or three days they can endure at this altitude for making summit bids. Clear weather and low winds are critical factors in deciding whether to make a summit attempt. If weather does not cooperate within these short few days, climbers are forced to descend, many all the way back down to Base Camp.
[[Image:Everest base camp.jpg|thumb|600px|A view of Everest southeast ridge [[Everest Base Camp|base camp]]. The [[Khumbu Icefall]] can be seen in the left. In the center are the remains of a helicopter that crashed in 2003.]]
From Camp IV, climbers will begin their summit push around midnight with hopes of reaching the summit (still another 1,000 metres above) within 10 to 12 hours. Climbers will first reach "The Balcony" at {{convert|8400|m|ft|-2|abbr=on}}, a small platform where they can rest and gaze at peaks to the south and east in the early dawn light. Continuing up the ridge, climbers are then faced with a series of imposing rock steps which usually forces them to the east into waist deep snow, a serious [[avalanche]] hazard. At {{convert|8750|m|ft|-2|abbr=on}}, a small table-sized dome of ice and snow marks the South Summit.<ref name=nova-climb/>
From the South Summit, climbers follow the knife-edge southeast ridge along what is known as the "Cornice traverse" where snow clings to intermittent rock. This is the most exposed section of the climb as a misstep to the left would send one 2,400 m (8,000 ft) down the southwest face while to the immediate right is the 3,050 m (10,000 ft) [[Kangshung face]]. At the end of this traverse is an imposing 12 m (40 ft) rock wall called the "Hillary Step" at {{convert|8760|m|ft|-1|abbr=on}}.<ref name=nova-climb/>
Hillary and Tenzing were the first climbers to ascend this step and they did it with primitive ice climbing equipment and without fixed ropes. Nowadays, climbers will ascend this step using fixed ropes previously set up by Sherpas. Once above the step, it is a comparatively easy climb to the top on moderately angled snow slopes - though the exposure on the ridge is extreme especially while traversing very large cornices of snow. With increasing numbers of people climbing the mountain in recent years, the Step has frequently become a [[bottleneck]], with climbers forced to wait significant amounts of time for their turn on the ropes, leading to problems in getting climbers efficiently up and down the mountain. After the Hillary Step, climbers also must traverse a very loose and rocky section that has a very large entanglement of fixed ropes that can be troublesome in bad weather. Climbers will typically spend less than a half-hour on "top of the world" as they realize the need to descend to Camp IV before darkness sets in, afternoon weather becomes a serious problem, or supplemental oxygen tanks run out.
=== Northeast ridge ===
[[Image:Everest North Face toward Base Camp Tibet Luca Galuzzi 2006 edit 1.jpg|thumb|right|300px|Everest North Face, Tibet]]
The northeast ridge route begins from the north side of Everest in Tibet. Expeditions trek to the [[Rongbuk Glacier]], setting up [[Everest Base Camp|Base Camp]] at {{convert|5180|m|ft|-1|abbr=on}} on a gravel plain just below the glacier. To reach Camp II, climbers ascend the medial moraine of the east Rongbuk Glacier up to the base of [[Changtse]] at around {{convert|6100|m|ft|-2|abbr=on}}. Camp III (ABC - Advanced Base Camp) is situated below the [[North Col]] at 6,500 m (21,300 ft). To reach Camp IV on the north col, climbers ascend the glacier to the foot of the col where fixed ropes are used to reach the North Col at {{convert|7010|m|ft|-2|abbr=on}}. From the North Col, climbers ascend the rocky north ridge to set up Camp V at around {{convert|7775|m|ft|-2|abbr=on}}. The route crosses the North Face in a diagonal climb to the base of the Yellow Band reaching the site of Camp VI at {{convert|8230|m|ft|-2|abbr=on}}. From Camp VI, climbers will make their final summit push. Climbers face a treacherous traverse from the base of the First Step: 27,890 feet - 28,000 feet, to the crux of the climb, the Second Step: 28,140 feet - 28,300 feet. (The Second Step includes a climbing aid called the "Chinese ladder", a metal ladder placed semi-permanently in 1975 by a party of Chinese climbers. It has been almost continuously in place since, and is used by virtually all climbers on the route.) Once above the Second Step the inconsequential Third Step is clambered over: 28,510 feet - 28,870 feet. Once above these steps, the summit pyramid is climbed by means of a snow slope of 50 degrees, to the final summit ridge along which the top is reached.<ref name=NOVA_wtsn>{{cite web|publisher=PBS NOVA|url=http://www.pbs.org/wgbh/nova/everest/climb/waytosummitnor.html|title=The Way to the Summit (North)|accessdate=2008-03-28}}</ref>
==Ascents==
[[Image:Mount Everest from Rombok Gompa, Tibet.jpg|frame|150px|Mount Everest as seen from the [[Rongbuk Monastery]].]]
{{main|Timeline of climbing Mount Everest}}
===Early expeditions===
In [[1885]], [[Clinton Thomas Dent]], president of the [[Alpine Club (UK)|Alpine Club]], suggests that climbing Mount Everest is possible in his book ''Above the Snow Line''.<ref>{{cite web |url=http://www.billbuxton.com/everest.pdf |title=From First Sight to Summit: A Guide to the Literature on Everest up to the 1953 Ascent |accessdate=2008-01-23 |format=[[PDF]] |author=William Buxton}}</ref>
The northern approach to the mountain was discovered by George Mallory on the first expedition in 1921. It was an exploratory expedition not equipped for a serious attempt to climb the mountain. With Mallory leading (and thus becoming the first European to set foot on Everest's flanks) they climbed the North Col (7007m 23,000-ft). From there, Mallory espied a route to the top. But the party was woefully unprepared for the enormity of climbing any further and descended.
The British returned in 1922. George Finch ("The other George") climbed using oxygen for the first time. He ascended at a remarkable speed--950 vert.-ft/hr, a feat that was entirely lost on the British climbing establishment--except for its unsporting nature. Mallory and Col.Felix Norton made a second unsuccessful attempt. Mallory was faulted for leading a group down fromn the North Col which got caught in an avalanche. Mallory was pulled down too, but seven native porters were killed.
The next Expedition was in 1924. During an initial attempt by Mallory, he aborted the climb and descended abruptly from C-V. While Norton and Somervell made their oxygenless attempt, reaching 28,100 ft in perfect weather, Norton ascending less then 100 ft in the least hour, Mallory rustled-up oxygen equipment for a last-ditch effort. He would choose Andrew Irvine, 22, as his partner.
On [[8 June]] [[1924]], [[George Mallory]] and [[Andrew Irvine (mountaineer)|Andrew Irvine]], both of the [[United Kingdom]], made an attempt on the summit via the north col/north ridge route from which they never returned. On [[1 May]] [[1999]], the [[Mallory and Irvine Research Expedition]] found Mallory's body in the predicted search area near the old Chinese camp. Controversy has raged in the [[mountaineering]] community as to whether or not one or both of them reached the summit 29 years before the confirmed ascent (and of course, safe descent) of Everest by Sir [[Edmund Hillary]] and [[Tenzing Norgay]] in 1953. The general [[consensus]] among climbers has been that they did not.
Mallory had gone on a speaking tour of the [[United States]] the year before in 1923; it was then that he is said ot have exasperatedly given the famous reply: "Because it's there!" to a [[New York]] [[journalism|journalist]] in response to hearing the question: "Why climb Everest?" for seemingly the thousandth time. Although this pithy quote will forever be remember as Mallory's, it was made up by the reporter who saw his performance, and described Mallory in a N.Y. Times article published on 18 March, 1923.
In 1933, [[Lucy, Lady Houston|Lady Houston]], a [[United Kingdom|British]] [[millionaire]] ex-[[showgirl]], funded ''the Houston Everest Flight of 1933'', which saw a formation of [[Westland Wallace|aircraft]] led by the [[Douglas Douglas-Hamilton, 14th Duke of Hamilton|Marquess of Clydesdale]] fly over the summit in an effort to deploy the British [[Union Flag]] at the top.<ref name=flymicro>[http://www.flymicro.com/everest/index.cfm?page=docs%2FHistory%2FAeroplanes.htm Aeroplane expeditions to Everest]</ref><ref name=k2news_woe>[http://www.k2news.com/wingsover.htm Wings Over Everest 2003] K2 News</ref>
Early expeditions – such as Bruce's in the 1920s and [[Hugh Ruttledge]]'s two unsuccessful attempts in 1933 and 1936 – tried to make an ascent of the mountain from [[Tibet]], via the north face. Access was closed from the north to western expeditions in 1950, after the [[People's Republic of China|Chinese]] reasserted control over Tibet. However, in 1950, [[Bill Tilman]] and a small party which included Charles Houston, Oscar Houston and Betsy Cowles undertook an exploratory expedition to Everest through Nepal along the route which has now become the standard approach to Everest from the south.<ref name=evhist_timeline>[http://www.everesthistory.com/time3.htm Time Line] Everest History</ref>
===First successful ascent by Tenzing and Hillary===
In 1953, a ninth British expedition, led by [[John Hunt, Baron Hunt of Llanfair Waterdine|John Hunt]], returned to Nepal. Hunt selected two climbing pairs to attempt to reach the summit. The first pair ([[Tom Bourdillon]] and [[Charles Evans]]) came within 100 m (300 feet) of the summit on [[26 May]] [[1953]], but turned back after becoming exhausted. As planned, their work in route finding and breaking trail and their caches of extra oxygen were of great aid to the following pair. Two days later, the expedition made its second and final assault on the summit with its second climbing pair, the [[New Zealand]]er [[Edmund Hillary]] and [[Sherpa (people)|Sherpa]] [[Tenzing Norgay]] from Nepal. They reached the summit at 11:30 a.m. local time on [[29 May]] [[1953]] via the South Col Route. At the time, both acknowledged it as a team effort by the whole expedition, but Tenzing revealed a few years later that Hillary had put his foot on the summit first.<ref>[[Tenzing Norgay]] and [[James Ramsey Ullman]], ''Man of Everest'' (1955, also published as ''Tiger of the Snows'')</ref> They paused at the summit to take photographs and buried a few sweets and a small [[cross]] in the snow before descending.
News of the expedition's success reached [[London]] on the morning of Queen [[Elizabeth II of the United Kingdom|Elizabeth II's]] [[coronation]]. Returning to [[Kathmandu]] a few days later, Hunt (a Briton) and Hillary (a subject of Elizabeth, through her role as [[head of state]] of New Zealand) discovered that they had been promptly [[Knighthood|knighted]] in the [[Order of the British Empire]], a KBE, for the ascent. Tenzing (a subject of the King of Nepal) was granted the [[George Medal]] by the UK. Hunt was ultimately made a [[life peer]] in Britain, while Hillary became a founding member of the [[Order of New Zealand]].
===First ascents without supplemental oxygen===
On [[8 May]] [[1978]], [[Reinhold Messner]] (Italy) and [[Peter Habeler]] (Austria) made the first ascent without supplemental oxygen, using the southeast ridge route.<ref name=NOVA_fwo>[http://www.pbs.org/wgbh/nova/everest/history/firstwoo2.html Everest - First without oxygen] PBS NOVA</ref><ref name=evhist/> On [[August 20]] [[1980]], Messner reached the summit of the mountain solo for the first time, without supplementary oxygen or support, on the more difficult Northwest route via the North Col to the North Face and the Great Couloir. He climbed for three days entirely alone from his base camp at {{convert|6500|m|ft|-2}}. This route has been noted as the 8th climbing route to the summit. <ref name=evhist/>
===1996 disaster===
{{main|1996 Everest Disaster}}
During the 1996 climbing season, fifteen people died trying to come down from the summit, making it the deadliest single year in Everest history. Eight of them died on May 11 alone. The disaster gained wide publicity and raised questions about the commercialization of Everest.
Journalist [[Jon Krakauer]], on assignment from ''[[Outside (magazine)|Outside]]'' magazine, was in one of the affected parties, and afterwards published the bestseller ''[[Into Thin Air]]'' which related his experience. [[Anatoli Boukreev]], a guide who felt impugned by Krakauer's book, co-authored a rebuttal book called ''[[The Climb (book)|The Climb]].'' The dispute sparked a large debate within the climbing community.<!-- sentence regarding Krakauer as a personna non grata removed until someone cites a source --> In May 2004, Kent Moore, a physicist, and John L. Semple, a surgeon, both researchers from the [[University of Toronto]], told ''[[New Scientist]]'' magazine that an analysis of weather conditions on May 11 suggested that freak weather caused oxygen levels to plunge approximately 14%.<ref name="NewScientist">
{{cite journal
| title = The day the sky fell on Everest
| journal = New Scientist
| volume =
| issue = 2449
| pages = 15
| publisher =
| date = 2004-05-29
| url = http://www.newscientisttech.com/article/mg18224492.200-the-day-the-sky-fell-on-everest.html
| accessdate = 2006-12-11 }}
</ref><ref name="BioEd Online">
{{cite web
| url=http://www.bioedonline.org/news/news.cfm?art=986
| title=High winds suck oxygen from Everest Predicting pressure lows could protect climbers.
| accessdate=2006-12-11
| last=Peplow
| first=Mark
| date=2004-05-25
| publisher=BioEd Online
| quote=Moore explains that these jet streaks can drag a huge draught of air up the side of the mountain, lowering the air pressure. He calculates that this typically reduces the partial pressure of oxygen in the air by about 6%, which translates to a 14% reduction in oxygen uptake for the climbers. Air at that altitude already contains only one third as much oxygen as sea-level air.}}
</ref>
The storm's impact on climbers on the mountain's other side, the North Ridge, where several climbers also died, was detailed in a first hand account by British filmmaker and writer [[Matt Dickinson]] in his book ''The Other Side of Everest''.
===2003 - 50th Anniversary of First Ascent===
2003 marked the 50th anniversary of the first ascent, and a record number of teams, including some very distinguished climbers, climbed or attempted to climb the mountain.
===2005 - Helicopter landing===
On [[14 May]] [[2005]], pilot [[Didier Delsalle]] of [[France]] landed a [[Eurocopter]] [[Eurocopter Ecureuil|AS 350 B3]] helicopter on the summit of Mount Everest<ref name="eurocopter">[http://www.eurocopter.com/site/docs_wsw/RUB_10101/pa-spe2006-06-03.pdf Legendary Pilots]</ref> (without any witness) and took off after about four minutes. (His rotors were continually engaged, constituting a "hover landing", and avoiding the risks of relying on the snow to support the aircraft.) He thereby set [[rotorcraft]] world records, for highest of both landing (de facto) and take-off (formally).<ref name="fai">[http://records.fai.org/rotorcraft/current.asp?id1=112&id2=1&id3=2 Federation Aeronautique Internationale] records page. (Search for "Everest" on that page).</ref>
Delsalle had also performed, two days earlier, a take-off from the South Col; some press reports suggested that the report of the summit landing was a misunderstanding of a South Col one.<ref name=everestnet>[http://www.mounteverest.net/story/FrenchEverestMysteryChoppersUtopiasummit-VIDEOMay272005.shtml French Everest Mystery Chopper's Utopia summit]</ref>
===2006 - David Sharp controversy===
Double-amputee climber [[Mark Inglis]] revealed in an interview with the press on [[May 23]], [[2006]]<ref name=abcnews052006>[http://www.abc.net.au/news/newsitems/200605/s1645603.htm Everest climber defends leaving dying Briton]</ref>, that his climbing party, and many others, had passed a distressed climber, [[David Sharp]], on [[May 15]], sheltering under a rock overhang 450 metres below the summit, without attempting a rescue. The revelation sparked wide debate on climbing ethics, especially as applied to Everest. The climbers who left him said that the rescue efforts would be useless and only cause more deaths because of how many people it would have taken to pull him off.
Much of this controversy was captured by the [[Discovery Channel]] while filming the television program ''[[Everest: Beyond the Limit]]''. A crucial decision affecting the fate of Sharp is shown in the program, where an early returning climber (Max Chaya) is descending and radios to his base camp manager (Russell Brice) that he has found a climber in distress. He is unable to identify Sharp, and Sharp had chosen to climb solo without any support, so he did not identify himself to other climbers. The base camp manager assumes that Sharp is part of a group that has abandoned him, and informs his climber that there is no chance of him being able to help Sharp [at 8000+ meters in altitude, barely anyone has the strength to help another man who is only semi conscious, and Max Chaya is only an amateur mountaineer]. As Sharp's condition deteriorates through the day and other descending climbers pass him, his opportunities for rescue diminish: his legs and feet curl from frost-bite, preventing him from walking; the later descending climbers are lower on oxygen and lack the strength to offer aid; time runs out for any Sherpas to return and rescue him. Most importantly, Sharp's decision to forgo all support leaves him with no margin for recovery.
As this debate raged, on [[May 26]], Australian climber [[Lincoln Hall (climber)|Lincoln Hall]] was found alive, after being declared dead the day before. He was found by a party of four climbers ([[Dan Mazur]], Andrew Brash, Myles Osborne and Jangbu Sherpa) who, giving up their own summit attempt, stayed with Hall and descended with him and a party of 11 Sherpas sent up to carry him down. Hall later fully recovered. Similar actions have been recorded since, including on [[21 May]] [[2007]], when [[Canada|Canadian]] climber Meagan McGrath initiated the successful high-altitude rescue of [[Nepal]]i Usha Bista.
===2008 - Summer Olympic torch summit===
{{main|2008 Summer olympics summit of Mt. Everest}}
China paved a {{convert|130|km|mi|abbr=on}} dirt road from [[Tingri County]] to its Base Camp in order to accommodate growing numbers of climbers on their side of the mountain. It will become the highest asphalt-paved road in the world. Construction began on [[18 June]] [[2007]] at a cost of 150 million yuan (US$19.7 million). China also routed the [[2008 Olympic Torch Relay]] over Everest, going up the South Col route and back down the North Col route, on the way to the [[2008 Summer Olympics]] in [[Beijing]].<ref>[http://www.msnbc.msn.com/id/24501387/ Olympic torch reaches Mount Everest summit]</ref> A [[China Telecom]] cellular tower near the Base Camp provides phone coverage all the way to the summit.<ref>[http://www.nytimes.com/2007/06/26/opinion/26kodas.html The Height of Avarice], ''The New York Times, June 26, 2007</ref>
===Various records===
According to the Nepalese government, the youngest person to climb Mount Everest was a 15-year-old Sherpa girl, and the youngest foreigner was 18-year-old Californian [[Samantha Larson]] in 2007.<ref>[http://www.usatoday.com/sports/2007-05-19-4256003039_x.htm 18-year-old California woman scales Everest, becoming youngest to complete 'seven summits'], ''The Associated Press'', 19 May 2007</ref>
The fastest ascent over the northeast ridge was accomplished in 2007 by Austrian climber [[Christian Stangl]], who needed 16h 42min for the 10km distance from Camp III to the summit, just barely beating Italian [[Hans Kammerlander]]'s record of 17 hours, accomplished in 1996. Both men climbed alone and without supplementary oxygen. The fastest oxygen-supported ascent over the southeast ridge was Nepalese Pemba Dorjie Sherpa's 2004 climb, using 8h 10min for the 17km route. The fastest ascent without supplementary oxygen over the southeast ridge was accomplished by French [[Marc Batard]] who needed 22h 30min in 1988.<ref>[http://www.mounteverest.net/news.php?id=16931 Everest 2008: Marc Batard back for speed record attempt on north side], MountEverest.net, 21 January 2008</ref>
The oldest climber to successfully reach Mt. Everest's summit was 76-year-old Min Bahadur Sherchan, who did so [[25 May]] [[2008]].<ref>76-year-old breaks Everest record</ref>
== Death zone ==
{{main|Death zone}}
While conditions for any area classified as a death zone apply to Mount Everest (altitudes higher than 8,000 m/26,246 ft), it is significantly more difficult for a climber to survive at the death zone on Mount Everest. Temperatures can dip to very low levels, resulting in [[frostbite]] of any body part exposed to the air. Because temperatures are so low, snow is well-frozen in certain areas and death by slipping and falling can also occur. High winds at these altitudes on Everest are also a potential threat to climbers. The atmospheric pressure at the top of Everest is about a third of sea level pressure, meaning there is about a third as much oxygen available to breathe as at sea level.<ref>{{cite web|url=http://www.altitude.org/calculators/airpressure.htm|title=Online high altitude oxygen calculator|accessdate=2007-08-15}}</ref>
In May 2007, the Caudwell Xtreme Everest undertook a medical study of oxygen levels in human blood at extreme altitude. Over 200 volunteers climbed to Everest Base Camp where various medical tests were performed to examine blood oxygen levels. A small team also performed tests on the way to the summit.<ref>{{cite web|url=http://www.xtreme-everest.co.uk/news_detail.php?article=196|title=Caudwell Xtreme Everest 2007|accessdate=2008-03-28}}</ref>
Even at base camp the low level of available oxygen had direct effect on blood oxygen saturation levels. At sea level these are usually 98% to 99%, but at base camp this fell to between 85% and 87%. Blood samples taken at the summit indicated very low levels of oxygen present. A side effect of this is a vastly increased breathing rate, from 20-30{{Fact|date=October 2007}} breaths per minute to 80-90 breaths, leading to exhaustion just trying to breathe.
Lack of oxygen, exhaustion, extreme cold, and the dangers of the climb all contribute to the death toll.
People who die during the climb are typically left behind. About 150 bodies have never been recovered. It is not uncommon that corpses are visible from the standard climbing routes.<ref>[http://www.theage.com.au/news/world/the-deadly-business-of-climbing-everest/2006/06/02/1148956544080.html?page=fullpage#contentSwap2 The deadly business of climbing Everest], ''[[The Age]]'', 3 June 2006</ref>
One sometimes deadly phenomenon, however, does not plague climbers — lightning. Lightning does not strike Mount Everest. [[NASA's lightning detection system]] does record significant lightning in the Tibet plateau, but none along the high Tibetan mountains, from about 2000 m (7,000 feet) and above.<ref>[http://www.weatherquesting.com/MtEverestLightning.htm Does lightning strike Mount Everest?]</ref>
== Bottled oxygen controversy ==
Most expeditions use [[oxygen mask]]s and tanks<ref>{{cite web|url=http://classic.mountainzone.com/everest/98/climb5-21oxygen.html|title=Mountainzone article.|accessdate=2007-04-01}}</ref> above 8,000 m (26,246 ft). Everest can be climbed without supplementary oxygen but this increases the risk to the climber. Humans do not think clearly with low oxygen, and the combination of severe [[weather]], low [[temperature]]s, and steep slopes often require quick, accurate decisions.
The use of bottled oxygen to ascend Mount Everest has been controversial. [[George Mallory]] himself described the use of such oxygen as unsportsmanlike, but he later concluded that it would be impossible to summit without it and consequently used it.<ref>{{cite web |url=http://www.pbs.org/wgbh/nova/everest/lost/mystery/ |title=NOVA Online | Lost on Everest | The Mystery of Mallory & Irvine '24 |accessdate=2008-01-23}}</ref> When [[Tenzing Norgay|Tenzing]] and Hillary made the first successful summit in 1953, they used bottled oxygen. For the next twenty-five years, bottled oxygen was considered standard for any successful summit.
[[Reinhold Messner]] was the first climber to break the bottled oxygen tradition and in 1978, with [[Peter Habeler]], made the first successful climb without it. Although critics alleged that he sucked mini-bottles of oxygen - a claim that Messner denied - Messner silenced them when he summited the mountain, without supplemental oxygen or support, on the more difficult northwest route, in 1980. In the aftermath of Messner's two successful ascents, the debate on bottled oxygen usage continued.
The aftermath of the [[1996 Everest Disaster|1996 disaster]] further intensified the debate. [[Jon Krakauer]]'s ''[[Into Thin Air]]'' (1997) expressed the author's personal criticisms of the use of bottled oxygen. Krakauer wrote that the use of bottled oxygen allowed otherwise unqualified climbers to attempt to summit, leading to dangerous situations and more deaths. The [[1996 Everest Disaster|May 11, 1996]] disaster was partially caused by the sheer number of climbers (33 on that day) attempting to ascend, causing bottlenecks at the Hillary Step and delaying many climbers, most of whom summited after the usual 2 p.m. turnaround time. He proposed banning bottled oxygen except for emergency cases, arguing that this would both decrease the growing pollution on Everest—many bottles have accumulated on its slopes—and keep marginally qualified climbers off the mountain.
The 1996 disaster also introduced the issue of the guide's role in using bottled oxygen.<ref name="salon">The debate between G. Weston DeWalt and Jon Krakauer on bottled oxygen and Boukreev's actions can be found in the [http://www.salon.com/wlust/feature/1998/08/07featurea.html Salon debates]</ref>
Guide [[Anatoli Boukreev]]'s decision not to use bottled oxygen was sharply criticized by Jon Krakauer. Boukreev's supporters (who include G. Weston DeWalt, who co-wrote ''[[The Climb (book)|The Climb]]'') state that using bottled oxygen gives a false sense of security.<ref>{{cite web |url=http://www.gsk.com/people/mogens/acclimatisation.htm |title=GlaxoSmithKline: On top of the world - Acclimatisation |accessdate=2008-01-23}}</ref> Krakauer and his supporters point out that, without bottled oxygen, Boukreev was unable to directly help his clients descend.<ref name="salongarner">[http://www.salon.com/wlust/feature/1998/08/cov_03feature3.html Coming Down page 3] DWIGHT GARNER ''salon.com'' 1998 August</ref> They state that Boukreev said that he was going down with client Martin Adams,<ref name="salongarner"/> but just below the South Summit, Boukreev determines that Adams was doing fine on the descent
and so descends at a faster pace, leaving Adams behind. Adams states in ''The Climb'': "For me, it was business as usual, Anatoli's going by, and I had no problems with that."<ref name=The_Climb>{{cite book|title=[[The Climb (book)|The Climb]]|last=Boukreev|first=Anatoli| coauthors=DeWalt, Weston|publisher=St. Martins Paperbacks|isbn=0-312-96533-8|pages=p. 182}}</ref>
==Thefts and other crimes==
Some climbers have reported life-threatening thefts from supply caches. [[Vitor Negrete]], the first Brazilian to climb Everest without oxygen and part of David Sharp's party, died during his descent, and theft from his high-altitude camp may have contributed.<ref>[http://www.mounteverest.net/news.php?id=2092 Mounteverest.net article]. See also [http://www.mounteverest.net/news.php?id=2069 second article.]</ref>
In addition to theft, the 2008 book ''High Crimes'' by Michael Kodas describes unethical guides and sherpas, prostitution and gambling at the Tibet Base Camp, fraud related to the sale of oxygen bottles, and climbers collecting donations under the pretense of removing trash from the mountain.<ref>[http://www.motherjones.com/arts/books/2008/02/go-sell-it-on-the-mountain.html Go Sell It on the Mountain], ''Mother Jones'', February 1, 2008</ref>
==Flora and fauna==
''[[Euophrys omnisuperstes]]'', a minute black [[jumping spider]], has been found at elevations as high as {{convert|6700|m|ft|-2}}, possibly making it the highest confirmed permanent resident on Earth. They lurk in crevices and possibly feed on frozen insects that have been blown there by the wind. It should be noted that there is a high likelihood of microscopic life at even higher altitudes.
<ref name=wanless>{{cite paper
| author = Wanless, F.R.
| title = Spiders of the family Salticidae from the upper slopes of Everest and Makalu
| date = 1975
| publisher = British Arachnological Society
| url =http://www.britishspiders.org.uk/
| format =
| accessdate = 2008-03-21 }}</ref>
[[Bird]]s, such as the [[bar-headed goose]], have been seen flying at the higher altitudes of the mountain, while others such as the [[Chough]] have been spotted as high as the South Col (7,920 m),<ref name=jhunt>''The Ascent of Everest'' by John Hunt (Hodder & Stoughton, 1953). In chapter 14, Hunt describes seeing a Chough on the South Col; meanwhile Charles Evans saw some unidentified birds fly over the Col.</ref> [[scavengers|scavenging]] on food, or even corpses, left over by climbing expeditions.
==Geology==
Geologists<ref name=Scientiav5>Yin, C.-H. and Kuo, S.-T. 1978: "Stratigraphy of the Mount Jolmo Lungma and its north slope." Scientia Sinica. v. 5, pp. 630-644</ref><ref name=IslandArcv14>Sakai, H., M. Sawada,Y. Takigami, Y. Orihashi, T. Danhara, H. Iwano, Y. Kuwahara, Q. Dong, H. Cai, and J. Li. 2005. "Geology of the summit limestone of Mount Qomolangma (Everest) and cooling history of the Yellow Band under the Qomolangma detachment." [[Island Arc]]. v. 14 no. 4 pp. 297-310.</ref> have subdivided the rocks comprising Mount Everest into three units called "[[Geologic formation|formations]]". Each of these formations are separated from each other by low-angle [[Fault (geology)|faults]], called “detachments”, along which they have been thrust over each other. From the summit of Mount Everest to its base these rock units are the Qomolangma Formation, the North Col Formation, and the Rongbuk Formation.
From its summit to the top of the Yellow Band, about 8,600 m above sea level, the top of Mount Everest consists of the Qomolangma Formation, which has also been designated as either the Everest Formation or Jolmo Lungama Formation. It consists of grayish to dark gray or white, parallel laminated and bedded [[limestone]] interlayered with subordinate beds of recrystallized [[dolomite]] with argillaceous laminae and [[siltstone]]. Gansser<ref>Gansser, A.1964.Geology of the Himalayas, John Wiley Interscience, London, 1964 289 pp.</ref> reported finding visible fragments of [[crinoid]]s in these limestones. Petrographic analysis of samples of this [[Ordovician]] limestone from near the summit revealed them to be composed of carbonate pellets and finely fragmented remains of [[trilobite]]s, crinoids, and [[ostracods]]. Other samples were so badly sheared and recrystallized that their original constituents could not be determined. The Qomolangma Formation is broken up by several high-angle faults that terminate at the low angle thrust fault, the Qomolangma Detachment. This detachment separates it from the underlying Yellow Band. The lower five metres of the Qomolangma Formation overlying this detachment are very highly deformed.<ref name=Scientiav5/><ref name=IslandArcv14/>
The bulk of Mount Everest, between 7,000 and 8,600 m, consists of the North Col Formation, of which the Yellow Band forms its upper part between 8,200 to 8,600 m. The Yellow Band consists of intercalated beds of diopsite-epidote-bearing [[marble]], which weathers a distinctive yellowish brown, and muscovite-biotite [[phyllite]] and [[schist|semischist]]. Petrographic analysis of marble collected from about 8,300 m found it to consist as much as five percent of the ghosts of recrystallized crinoid ossicles. The upper five metres of the Yellow Band lying adjacent to the Qomolangma Detachment is badly deformed. A 5–40 cm thick fault [[breccia]] separates it from the overlying Qomolangma Formation.<ref name=Scientiav5/><ref name=IslandArcv14/>
The remainder of the North Col Formation, exposed between 7,000 to 8,200 m on Mount Everest, consists of interlayered and deformed schist, phyllite, and minor marble. Between 7,600 and 8,200 m, the North Col Formation consists chiefly of biotite-quartz phyllite and chlorite-biotite phyllite intercalated with minor amounts of biotite-sericite-quartz schist. Between 7,000 and 7,600 m, the lower part of the North Col Formation consists of biotite-quartz schist intercalated with epidote-quartz schist, biotite-calcite-quartz schist, and thin layers of quartzose marble. These metamorphic rocks appear to the result of the metamorphism of deep sea [[flysch]] composed of interbedded, [[mudstone]], [[shale]], clayey [[sandstone]], calcareous sandstone, [[graywacke]], and sandy limestone. The base of the North Col Formation is a regional thrust fault called the “Lhotse detachment”.<ref name=Scientiav5/><ref name=IslandArcv14/>
Below 7,000 m, the Rongbuk Formation underlies the North Col Formation and forms the base of Mount Everest. It consists of sillminite-K-feldspar grade schist and [[gneiss]] intruded by numerous [[Sill (geology)|sills]] and [[Dike (geology)|dikes]] of [[granite|leucogranite]] ranging in thickness from one cm to 1,500 m.<ref>Searle, M. P. 1999. Emplacement of Himalayan leucogranites by magma injection along giant sill complexes: examples from the Cho Oyu, Gyachung Kang and Everest leucogranites (Nepal Himalaya). Journal of Asian Earth Sciences. v. 17, no. 5-6, pp. 773-783.</ref><ref name=IslandArcv14/>
==Image gallery==
<center><gallery>
Image:Mount Everest from Rongbuk may 2005.JPG|View of Mount Everest from the Rongbuk Monastery
Image:Everest nubtse.jpg|Mount Everest and Nubtse from Kala Patthar
Image:Sagarmatha ck Oct18 2002.jpg|Sagarmatha (Mount Everest) as seen from Kala Pattar
Image:Everestpanoram.jpg|Northern panoramic view of Everest from Tibetan Plateau KS
Image:Sunset on Everest.JPG|The last rays of sunlight on Mount Everest on May 5, 2007
</gallery></center>
==See also==
{{commons|Mount Everest}}
*[[List of highest mountains|Highest mountains of the world]]
*[[North Col]]
*[[South Col]]
*[[Rongbuk Glacier]]
*[[Rongbuk Monastery]]
*[[Kangshung Face, Mount Everest]]
*[[Geography of China]]
*[[Sagarmatha National Park]]
*[[Geology of the Himalaya]]
*[[List of deaths on eight-thousanders]]
==Bibliography==
* ''American Alpine Journal'' 2005, p. 393.
*[[Robert Lock Graham Irving|Irving, R. L. G.]], ''Ten Great Mountains'' (London, J. M. Dent & Sons, 1940)<ref>The climbing history up to 1939 of [[Snowdon]], [[Ben Nevis]], [[Ushba]], [[Mount Logan]], [[Mount Everest|Everest]], [[Nanga Parbat]], [[Kangchenjunga|Kanchenjunga]], the [[Matterhorn]], [[Aoraki/Mount Cook|Mount Cook]] and [[Mont Blanc]].</ref>
== References ==
{{reflist|2}}
<!-- <ref name=doublecross/><sup>[[Wikipedia:Footnotes|[broken footnote]]]</sup> -->
== External links ==
{{wikiquote}}
* [http://www.everesthistory.com/everestsummits/summitsbyyear.htm Summits and deaths per year]
* [http://www.nationalgeographic.com/everest/ ''National Geographic'' site on Mt. Everest]
* [http://www.pbs.org/wgbh/nova/everest/ NOVA site on Mt. Everest]
* [http://imagingeverest.rgs.org/Concepts/Imaging_Everest/ Royal Geographical Society site on Mt. Everest]
* [http://thegreatindian.tripod.com/mountEverest.htm Mount Everest panorama], [http://www.panoramas.dk/fullscreen2/full22.html Mount Everest interactive panorama (Quicktime format)], Virtual panoramas *[http://www.viewfinderpanoramas.org/panoramas/ASIA/Everest-North.gif North] *[http://www.viewfinderpanoramas.org/panoramas/ASIA/Everest-South.gif South]
* [http://dsc.discovery.com/convergence/everest/interactive/interactive.html Interactive climb of Everest] from Discovery Channel
* [http://www.summitpost.org/mountain/rock/150230/everest.html Mount Everest on Summitpost]
* [http://www.therestofeverest.com/ The Rest of Everest video podcast]
* [http://www.viewfinderpanoramas.org/climbers.html Full list of all 3,679 ascents of Everest up to and including 2007 (in Excel format)]
* [http://www.yetizone.com/Everest/Trek/Everest_Trek.shtml The Everest Trek guidebook]
* [http://www.everestnews2004.com/malloryandirvine2004/malloryandirvine2004.htm Mallory and Irvine: The Final Chapter] -- controversy
* [http://www.everest1953.co.uk/ Mount Everest The British Story]
* [http://www.cnn.com/2008/WORLD/asiapcf/05/25/everest.old.ap/index.html 76-year-old breaks Everest record]
<!-- PLEASE NOTE: Before adding links to this section, please discuss your changes on the talk page for consideration -->
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[[Category:Sacred mountains]]
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[[Category:Xigazê Prefecture]]
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