Everest taller by 2 feet: China, Nepal- jointly announced a new height at 8848.86 metres, or 29,031 feet

A new Survey of India calculation in 1954 placed the height at 29,028 feet

Everest was crowned the world’s highest in 1856 after pivotal calculations by Calcutta-based mathematician Radhanath Sikdar. : Shutterstock

TT   |   New Delhi   |    09.12.20  : China and Nepal on Tuesday jointly announced a new height of Mount Everest at 8848.86 metres, or about 29,031 feet, two feet higher than what Chinese surveyors had measured 15 years ago.

China’s Xinhua news agency reported that the Chinese President, Xi Jinping, and his Nepali counterpart, Bidya Devi Bhandari, exchanged letters announcing the peak’s new height. Everest was crowned the world’s highest in 1856 after pivotal calculations by Calcutta-based mathematician Radhanath Sikdar.

Sikdar, who was the “chief computer” at the Survey of India, had used field observations by several other surveyors to calculate a height of 29,002 feet for Peak XV as Mount Everest had then been designated.

A new Survey of India calculation in 1954 placed the height at 29,028 feet. China has since the 1960s conducted multiple campaigns to measure Everest’s height, combining traditional trigonometry with increasingly sophisticated techniques such as laser ranging and satellite-aided measurements.

A Chinese campaign in 2005 had yielded a height of 8847.93 metres, or about 29,029 feet. The height jointly announced by China and Nepal on Tuesday is two feet higher.

While the Himalayas as a whole are rising under the influence of plate tectonics — the subduction of the Indian continental plate beneath the Eurasian plate — the two-feet difference between 1975 and 2020 is unlikely to be the result of tectonics, geologists said.

“The difference is more likely the outcome of precision measurements, more sophisticated instrumentation,” Vimal Singh, assistant professor of Himlayan geology at the University of Delhi told The Telegraph. “A two-feet rise in 45 years is difficult to explain through tectonics.”

Geological observations have indicated different rise rates along the mountain chain. “The rise is not uniform every year — we calculate an average rise over periods of hundreds to thousands of years. But even in areas of maximum observed rise an estimate would be about 10 mm per year,” Singh said.

A steady 1 cm rise each year over 15 years translates into only a half-foot rise. Geologists say periodic high-precision measurements would be needed to specifically determine the effect of tectonics on Mount Everest.

Chinese researchers had in 2005 for the first time used ground penetration radar to determine the thickness of the snow cover on Mount Everest. Their calculations had yielded the snow surface height to be 8847.93 metres and the rock surface height as 8844.43 metres.