Sherpa often serve as mountaineer guides and porters on mountain-climbing expeditions. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society.
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The snow and ice on the mountain create deadly hazards like avalanches, and there is only a limited climbing season due to bad weather conditions. But perhaps the biggest danger is the altitude. Most climbers are not accustomed to the high altitude and low oxygen levels and rely on bottled oxygen they bring along.
With more people has also come more pollution up near the summit as climbers often discard unwanted items all along the mountain. Additionally, the Sherpa people have been exploited by climbers, and their traditional way of life has been disrupted by foreign climbers.
Sherpa guides are faced with some of the highest death rates of any field of employment, for comparatively little pay. They calculated sea level by building a network of line-of-sight stations from the Bay of Bengal, the closest swath of ocean, zigzagging north from hilltop to hilltop, all the way until Everest was visible and could be measured using trigonometric calculations.
To take the curvature of the Earth into account, surveyors used spheroid models—rough, rounder precursors to the more mathematically complex ellipsoid models. They came up with an altitude of 29, feet. That calculation proved remarkably accurate. In , a survey led by cartographer and explorer Bradford Washburn and sponsored by the National Geographic Society used GPS technology and came up with an altitude only six feet higher than the measurement.
In , a Chinese survey set the rock height of the mountain at 29, feet. The National Geographic Society uses the survey figure of 29, feet. The team ultimately decided to conduct both a GPS survey and a leveling survey a 19th-century technique still in use but now done with modern laser equipment. In addition to calculating the height of the highest rock, they also calculated the height including the snow and ice layer.
Since Nepal shares Mount Everest with China—the border dividing Nepal from China-controlled Tibet runs through the summit—the matter of determining its new official height is infused with diplomatic considerations. Four months after Gautam and his colleagues completed their fieldwork, Chinese President Xi Jinping made a state visit to Nepal , arriving in Kathmandu on October 12, During the visit, China and Nepal announced an agreement to cooperate on the re-measurement of Everest and jointly announce the findings.
This spring, while virtually all Everest expeditions were cancelled due to the COVID pandemic, one group reached the summit: a surveying team from China , which conducted their own measurements.
A Chinese plane carrying precision gravity survey equipment also flew over the mountain. In late May, after the Chinese survey team completed their Everest expedition, Chinese authorities suggested the new elevation would be ready in two to three months, but there have been no further updates. The precision of this measuring mission will be better than any other previous mission.
Douglas notes that, like Nepal, China has long used Everest as a symbol of national identity. In , Mao Zedong ordered a large state-run expedition of Everest. That team made the first successful ascent from the Tibet side of the mountain. During the Beijing Olympics, China imposed restrictions on climbers on the Tibet side of the mountain so that an official expedition could carry the Olympic torch to the top without incident.
Nepal's lead surveyor Khimlal Gautam lost his toe due to frostbite while on the summit to install height-measuring equipment last year. Why else has the height been questioned?
Some geologists have suggested a major earthquake in may have had an impact on Mount Everest's height. The 7. At least 18 climbers were killed. Some geologists said the earthquake may have caused Everest's snow cap to shrink. Scientists had found that some other Himalayan peaks such as Langtang Himal, mostly to the north of Kathmandu and close to the epicentre, had reduced in height by approximately a metre after the earthquake.
Others have argued that Mount Everest, like other Himalayan peaks, may have actually grown over time because of the shifting tectonic plates it sits on. But experts say major earthquakes can result in that process being reversed. The heights of mountains are measured with the mean sea level as the base. So it's less about working out the where the top is, than where the bottom would be. Nepal used the Bay of Bengal as its sea level, but India had already surveyed a point closer to Everest, near the India-Nepal border, from the bay, and was able to provide the Nepalese surveyors with the height at that point.
From there, Nepal built a network of line-of-sight stations stretching nearly km miles to the point Everest first become visible, creating a chain of points it could measure and add together.
The Chinese surveyors, according to the state-run China Daily, used the Yellow Sea in the eastern province of Shandong as their sea-level base. Surveyors from both sides also used trigonometry formulas to calculate the height of the summit.
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