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Mount Everest, the highest mountain on Earth, rises to 8,849 meters. And it’s still getting taller. British and Chinese researchers have uncovered why. They used computer modeling and GPS measurements. Mount Everest, also called Chomolungma in Tibetan and Sagarmatha in Nepali, stands 238 meters taller than its nearest neighbor. The researchers say Everest’s unusual size can be explained by the behavior of a nearby river system.
Lead author Adam Smith from University College London said, “Mount Everest is a magnificent mountain steeped in myths and legends, and it continues to rise. Our research shows that as the surrounding river system carves deeper, the loss of material causes the mountain to grow even higher.” The main culprit behind this is likely the Arun River, which flows past the mountain to the east before joining the larger Koshi River. Over thousands of years, the Arun has carved a deep gorge through the Himalayas, removing billions of tons of rock.
The erosion of such vast amounts of rock has triggered isostatic rebound, a process reported by IFLScience. Dr. Xu Han from the China University of Geosciences explained, “The interaction between the erosion of the Arun River and the upward pressure from the Earth’s mantle gives Mount Everest a boost, raising it higher than it would otherwise be.”
By calculating erosion rates across the river network, the researchers concluded the Arun and Koshi rivers merged about 89,000 years ago. That confluence increased the magnitude of isostatic rebound and led to more land and sediment being washed away. Geologists call that drainage piracy. The team estimated that since the rivers merged, Mount Everest has grown by about 50 meters.
Previous estimates put Everest’s rise at roughly one millimeter per year. The new study suggests the summit is gaining about two millimeters annually. The findings were published in the journal Nature Geoscience.
