Now you really have got a mountain to climb…

THE world’s highest peak just became a tiny bit higher. Nepal and China, the two countries that share a border on Mount Everest, yesterday announced a new official measurement of the mountain’s height – 8 848.86 metres (29 031.69 feet). That’s about three feet higher than the most commonly used measure of Everest’s height that came from a survey conducted by India in the early 1950s.

The announcement, broadcast live on national television in Nepal, is the culmination of an exhaustive process involving two trips to the summit and years of measurements to calculate Everest’s precise height above sea level.

“We can be confident that this is the most accurate height of Everest that we have ever had,” said Susheel Dangol, Nepal’s chief survey officer, who headed the project. “It was a huge responsibility on our part. It is a moment of great pride for us.”

Experts say the new figure is likely to become the standard height for Everest. “It will be difficult to improve on the new number,” said Roger Bilham, a geologist at the University of Colorado. The measurements taken by Nepal are “remarkable for their density”.

Geologists say the height of Everest is a moving target, thanks to shifting tectonic plates and the occasional earthquake. The former pushes the mountain’s height ever-so-slightly upward each year, while the latter can cause it to sink. For Nepal, the drive to measure Everest was partly an exercise in national pride. Despite being home to the world’s highest peak, Nepal had never conducted its own measurement.

Starting in 2018, Nepal announced it would spend $1.3 million (about R19.5m) on the project. The country’s surveyors employed two methods to measure the mountain. The first was based on trigonometry, a time-tested technique that is also known as a levelling survey. The second used the latest technology, relying on a combination of readings from a satellite navigation system and a complex model of sea level. It wasn’t easy… a Nepalese surveyor who lugged a global positioning device and a ground-penetrating radar to the summit of Everest last year lost the tip of a toe to frostbite. His team faced a life-threatening shortage of oxygen on their descent.

Other surveyors transported a $200 000 piece of equipment called a gravimeter to 297 spots in Nepal. The gravimeter measures the force of gravity at a given location. Its readings are crucial to forming the detailed model of where sea level lies beneath Everest’s hulk of rock (satellite readings alone are not sufficient to calculate height above sea level).

The new joint measurement also has an element of geopolitics. Following a visit by Chinese President Xi Jinping to Nepal last year, the two countries agreed to collaborate on the effort, said Buddhi Narayan Shrestha, the former director-general of Nepal’s survey department who was also a senior adviser on the project. China conducted its own measurement.

The calculations by both countries “couldn’t have been more accurate”, Shrestha said.