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Scientists baffled by Everest growth spurt - 21st October 2024

Rising an astounding 8,849 metres, Mount Everest holds the record as the highest point on Earth. Now, scientific evidence indicates that the rate at which this colossus is climbing skywards has almost doubled.

Everest is the jewel in the crown of the Himalayas, which originated approximately 50 million years ago following the collision of the Indian subcontinent tectonic plate into the Eurasian continental plate. Although this is an ongoing geologic event, a research team from China and the UK’s indicated that tectonic convergence alone doesn’t account for the pace of Everest’s rise.

Writing in the journal Nature Geoscience, co-author Professor Dai Jingen from the China University of Geosciences wrote, “this raised the question of whether there was an underlying mechanism making Everest’s anomalous elevation even higher”.

Their investigations have identified the probable cause to be ‘river capture’. Nearly 90,000 years ago, the confluence of the Kosi and Arun rivers generated a forceful torrent of water which has rapidly eroded the rock and earth in its path. The river flows approximately 80 kilometres from Everest’s base.

This has transported millions of tonnes of mass away, lightening the Earth's crust, which allows for a phenomenon called isostatic rebound. This is where the internal pressure below the crust pushes the Earth back out into shape as the additional weight on the surface reduces. “Effectively, as the river incised deeper into the geological strata and transported away sediment, the underlying crust rebounded upwards, analogous to how a vessel rises when its cargo is offloaded,” elaborated Dr Dai.

The team believes this has contributed an additional 15 to 50 metres to Everest’s height over the past 89,000 years. It’s estimated that Everest’s peak continues to climb by approximately 0.16 to 0.53 millimetres every year beyond the rise caused by tectonic convergence. This seemingly negligible increase is astounding in geological terms.

Co-author of the study Dr Matthew Fox from University College London, highlights other potential contributors. The depletion of mountain glaciers and the tectonic stress from seismic activity could impact the effect.

Whatever the cause, mountaineers now ascend ever so slightly higher at Earth’s highest point.