Mount Everest, the world’s highest peak, is getting even higher thanks to an unexpected source: a river. New research from University College London (UCL) reveals that erosion from the Arun River, located 75km (47 miles) away, is causing Everest to rise by up to two millimetres a year, reports the BBC.
“It’s like taking cargo off a ship,” explained study co-author Adam Smith. “The ship rises higher as it becomes lighter. Similarly, the Earth’s crust floats a bit higher when it becomes lighter.”
The Arun River carves away rock and soil as it flows through the Himalayas, reducing the weight on the Earth’s mantle. This causes the crust to flex and “rebound” upwards, a phenomenon known as isostatic rebound. This rebound is pushing Everest and its neighbouring peaks, including Lhotse and Makalu, upwards at a faster rate than erosion is wearing them down.
“We can see them growing by about two millimetres a year using GPS instruments,” said Dr Matthew Fox, another co-author of the study. “Now we have a better understanding of what’s driving it.”
Everest grown 15-50 metres taller over the ages
The study, published in Nature Geoscience, estimates that Everest has grown 15-50 metres taller over the past 89,000 years due to this effect. The Arun River likely gained its erosive power after “capturing” another river or water body in Tibet, increasing its flow and ability to carve away material.
While the tectonic collision of the Indian and Eurasian plates remains the primary driver of Himalayan growth, this research highlights the significant role erosion plays in shaping the Earth’s landscape. Some geologists not involved in the study have said that while the theory is plausible, further research is needed to confirm the exact amounts and timescales involved in this process.
This discovery adds another layer of complexity to the ongoing study of Mount Everest, a peak that continues to fascinate and challenge scientists and climbers alike.