Mount Everest's height is fixed
The core idea stands, but key numbers or details have changed.
TaughtMount Everest is a certain fixed height. It rose when India collided with Asia millions of years ago, and now it just stands there as the world's tallest mountain.
NowA 2024 study found Everest is actively growing, rising up to about 2 millimetres a year, and is 15 to 50 metres taller than it 'should' be because a river gorge 75 km away is eroding away rock and letting the crust below rebound upward. The mountain is being pushed up by the loss of land nearby.
What actually happened
The mechanism is isostatic rebound. Earth's crust floats on the denser mantle, so when a large mass of rock is removed from the surface, the crust underneath springs up to compensate, the same process that is still lifting Scandinavia and Canada as the weight of Ice Age glaciers disappears. For Everest, the eroding mass is a deep gorge being carved by the Arun river system.
The trigger was an act of 'river piracy' about 89,000 years ago, when the Arun was captured by and merged into the lower Kosi river network. The combined river became far more erosive, excavating a huge volume of rock from the gorge and unloading the crust, which nudged Everest and its neighbours Lhotse and Makalu measurably higher. The Nature Geoscience team estimated 15 to 50 metres of extra height accumulated this way.
The update is to the idea of a mountain as a static monument. Everest already made news in 2020 when China and Nepal jointly revised its official height to 8,848.86 m; the 2024 finding explains part of why that height is not merely a better measurement of a fixed object but a snapshot of something still slowly rising.
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Who was taught this
Still standard through 2024, so anyone who finished school between 1950 and 2024 learned the earlier version.