Nepal and China have jointly announced that the height of the world highest peak, Mount Everest, has increased by 0.86 metres compared to previous measurements. Both countries have agreed on a new height of 8,848.86 metres (29,032 feet). Previously, there was a disagreement between the two nations on whether the snow cap at the summit should be included in the height measurement.
China’s previous official measurement was 8,844.43 metres, which was four metres less than the measurement made by Nepal.
Mount Everest is located on the border between China and Nepal, and climbers ascend from both sides. Officials from Nepal Ministry of Foreign Affairs and the Department of Survey reported that survey teams from both countries worked together to agree on the new height. Last year, during Chinese President Xi Jinpin visit to Kathmandu, an agreement was made to jointly announce the new measurement of the world’s highest peak.
Why the Discrepancy in Official Height?
Previously, Chinese authorities argued that Mount Everest should be measured by its rocky height, while Nepalese authorities believed that the snow cap at the summit should also be included. The Chinese survey teams had released their data following the summit measurement in 2005.
Nepalese officials told the BBC in 2012 that they felt pressured by China to accept its measurement, which led them to decide to conduct a new measurement. Nepal has been using the height of 8,848 metres, determined by the Survey of India in 1954, but for the first time, Nepal has measured the summit itself. Four surveyors from Nepal underwent two years of training for this mission.
Nepal’s Department of Survey spokesperson, Damodar Dhakal, told the BBC, “We had never done the measurement ourselves before.” Dhakal added, “Now that we have a young, technical team (capable of going to the Everest summit), we can do it ourselves.”
Are There Other Reasons for Height Questions?
Some geologists believe that the major earthquake in 2015 might have affected Mount Everest’s height. The earthquake, with a magnitude of 7.8, killed around 9,000 people in Nepal, and an avalanche buried parts of Everest’s base camp under snow. At least 18 climbers were killed in this incident. Some geologists suggested that the earthquake might have caused the snow cap on Everest to shrink. Scientists noted that other Himalayan peaks, such as Langtang Lirung, which is located north of Kathmandu and close to the earthquake’s epicentre, experienced a reduction in height of about one metre after the earthquake.
Other scientists suggest that, like other Himalayan peaks, Mount Everest might have grown higher over time due to shifting tectonic plates. However, experts also mention that significant earthquakes could alter the direction of such changes.
Dhakal says, “One reason for re-measuring the summit is also the 2015 earthquake.”
How Was Mount Everest Re-Measured?
Mountain heights are measured in relation to sea level. Therefore, measuring the summit’s height is less significant than measuring its elevation from sea level. Nepal used the Bay of Bengal as the reference level, but India had already surveyed the Everest’s proximity to the Bay of Bengal near the India-Nepal border. India assisted Nepal survey team in determining the height of this reference point.
From this reference point, Nepal created a network covering about 250 kilometres (155 miles) of all locations where Everest’s summit could be seen. The Nepali team then measured all these locations and compiled the data. According to Chinese state media, the Chinese survey team used the Yellow Sea in Shandong Province as the sea level reference.
Surveyors from both sides also used trigonometric formulas to calculate the summit’s height. These formulas involve multiplying the lower part of a triangle by angles to determine the summit’s height. However, someone needs to be on the mountain’s summit for this complex calculation. The Nepali survey team went to the summit last year, while the Chinese survey team arrived there in May this year. Due to the COVID-19 pandemic, Nepal suspended all expeditions, and China imposed restrictions on foreign travellers, making the Chinese team the only one to reach the summit in 2020.
Nepali officials stated that they used 12 lower peaks around Everest’s summit to achieve more accurate results. Chinese media reported that the Chinese survey team also used this method.
Yang Tao, an associate researcher at the Chinese Academy of Surveying and Mapping, told China Daily, “Once the survey team reached the summit, the team members at nearby stations measured the distance from the summit from six locations, meaning that the height of the mountain could be determined using at least six triangles.” Both parties also used the Global Navigation Satellite System to gather elevation data. China had previously measured Mount Everest’s height twice: once in 1975 and again in 2005.
According to the Himalayan Database, the members of the second survey team had installed a Chinese version of the GPS device on the summit. This time, the Chinese survey team used China BeiDou Navigation Satellite System, which is considered a competitor to the U.S. Global Positioning System (GPS). According to China’s official news agency Xinhua, “This system can measure weather, wind speed, and snow depth, which will aid not only in monitoring glaciers but also in environmental protection.”
