Context

After more than a decade of dispute and controversy, China and Nepal have finally agreed on how tall Mount Everest is.

About

• Mount Everest—known in Nepali as Sagarmatha and Tibetan as Chomolungma—straddles the border between Nepal and Tibet at the crest of the Himalayan mountain chain.
• Everest is 50 to 60 million years old, a youngster by geological standards.
• The mountain was formed by the upward force generated when the Indian and Eurasian tectonic plates collided, pushing up the rocks that formed the highest mountain on Earth. 

Why did Mount Everest’s height change?

• The mountain’s height changes. The movement of tectonic plates can lift it up ever so gradually, while earthquakes can bring it down.

The new height

• Nepal and China jointly announced that the revised height of the world's highest peak Mount Everest was 8,848.86 metres, about 86 centimetres more than the previous measurement done by India in 1954.
• This is less than a meter higher than the previously recognized height.
• The new height was calculated using a combination of geodetic data received from three mechanisms: leveling instrument, gravity meter and GPS. The team placed a signal receiver at every station, and measured how much time it took for signals to travel between the receiver and satellites — then converted that measurement into height.
• How high above sea level is just one way of measuring a mountain’s height. One reason Everest wins the prize is that its base sits high up on already lofty foothills.

As measured from the Earth’s core, Ecuador’s Mount Chimborazo is the world’s highest, standing more than 2,072 metres (6,800 feet) above Everest. Because the Earth bulges in the middle, mountains along the equator are farther from the core. Measuring from the foot of the mountain to the peak, Hawaii’s Mauna Kea is the tallest. Most of it, however, is under the sea.

End to a long-running debate

• The agreement marked the end to a long-running debate over the precise dimensions of the mountain, known as Sagarmatha in Nepal and Qomolangma in Tibet.
• Over the years, the two countries, as well as other governments around the world, have offered up differing estimates of the mountain's height.
• In 2005, a Chinese survey of the mountain estimated that it stood at around 8,844 meters (about 29,015 feet).
• However, since the research was not authorized by Nepal, the country did not recognize it as the official height. At the time, they were using a figure of 8,848 meters (29,029 feet), in line with the findings of a 1955 Indian survey.
• Then in 2015, multiple scientific studies suggested the mountain's elevation may have changed after a 7.8-magnitude earthquake hit Nepal.
• Two years later, the Nepali government for the first time kicked off its own long and arduous mission of re-measuring the height.