The highest point on Earth got a bit higher on Tuesday as China and Nepal finally agreed on a precise elevation for Mount Everest after years of debate.
The agreed height of 8,848.86 metres (29,031 feet) — unveiled at a news conference in Kathmandu — was 86 centimetres (2.8 feet) higher than the measurement previously recognised by Nepal, and more than four metres above China’s official figure.
This discrepancy was due to China measuring the rock base on the summit and not — as with the new reading — the covering of snow and ice on the peak.
Everest straddles the border of Nepal and China.
Employing trigonometry hundreds of miles away on the Indian plains, British colonial geographers first determined Everest’s height in 1856 at 8,840 meters (29,002 feet) above sea level.
After Edmund Hillary and Tenzing Norgay Sherpa famously first reached the summit of Everest on May 29, 1953, an Indian survey readjusted the altitude to 8,848 meters (29,028 feet).
That measurement was widely accepted, with the number appealing not only to ambitious mountaineers but also inspiring names for adventure clothing lines, restaurants and even a vodka brand.
In 1999 the US National Geographic Society concluded the world’s highest point was 8,850 meters (29,035 feet), but Nepal never officially recognised this — although it is widely quoted.
China meanwhile conducted several surveys of its own, and in 2005 came up with a measurement of 8,844.43 metres (29,015 feet).
The provoked a row with Nepal, which was only resolved in 2010 when Kathmandu and Beijing agreed that their measurements referred to different things — one to the height of Everest’s rock and the other to the height of its snowcap.
Nepal decided to conduct a survey — initially alone and later joined by China — after suggestions that tectonic plate movements including a major earthquake in 2015 may have affected the height.
About 300 Nepali experts and surveyors were involved in the exercise — some on foot and others in helicopters — to reach data collection stations.
Last spring, Nepali surveyors reached the summit of Everest with over 40 kilograms (90 pounds) of equipment, including a Global Satellite Navigation System (GNSS) receiver.
They spent roughly two freezing hours collecting data as dozens of climbers stood on top of the mountain.
“Climbing Everest alone is a challenging task, but we also had to measure it,” Khim Lal Gautam, a Survey Department official who lost a toe to frostbite in the expedition, told AFP.
Nepal was due to release the results earlier this year but then China became involved after a visit to Nepal in October 2019 by President Xi Jinping.
This year a Chinese survey expedition had a more quiet working space on the summit as they were the only climbers on a mountain shut because of the coronavirus pandemic.
Dang Yamin, an expert at the National Bureau of Surveying and Mapping, told Chinese state broadcaster CCTV that the final result was an average value between the measurements by Nepal and China, in accordance with scientific rules.
“Various countries have completed the measurement of the height… several times,” said Padma Kumari Aryal, Nepal’s land minister.
“The results have been different on different occasions, so today we end these speculations.”