Mount Everest Is Growing Taller — Scientists Explain Why

The reason behind the surprising growth could be credited to two ancient rivers.

Mount Everest is the world's highest mountain standing at 8.85 km above sea level.

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Mount Everest, the world's highest mountain standing at 8.85 km above sea level, has grown taller by around 15 to 50 metres in the last 89,000 years, and it's increasing every year, as per a study published in Nature Geoscience. The reason behind the surprising growth could be credited to two ancient rivers that flowed through the Himalayas and merged about 89,000 years ago, the researchers said.

The resulting erosion removed so much rock and soil that Everest has rebounded upwards by as much as 50 metres, they said. "The outer crust of Earth responds to the removal of mass by slowly rising," said co-author Matt Fox, a geologist at University College London. He added that this has increased the elevation of Everest.

Understanding The Nearby Arun River

Everest's extreme height could be explained after understanding the path of the nearby Arun River. When the Arun River joined with another nearby river, the new path created the deep Arun Gorge near Everest, the researchers said. Scientists think that the Arun river once had a different course and that it eroded its way through the mountains until it merged with a northerly river. This kind of event is known as river capture or river piracy. 

"Mount Everest is a remarkable mountain of myth and legend and it's still growing," said co-author Adam Smith. "Our research shows that as the nearby river system cuts deeper, the loss of material is causing the mountain to spring further upwards," he added.

Geologist Peter Van Der Beek at the University of Potsdam in Germany pointed out that in 2015, a magnitude-7.8 earthquake in Nepal caused many Himalayan mountains to subside by around 1 metre. Over long timescales, multiple big quakes can significantly affect mountain height, he said.