Why is world's tallest mountain Everest growing even taller?

Isostatic rebound causes Everest to rise 0.01-0.02 inches yearly, offsetting surface erosion from wind and rain.

Mount Everest, the world’s tallest peak at 8.85 km above sea level, is growing taller at a faster pace than previously thought, according to a new study published in Nature Geoscience.

Scientists have long known that the Himalayas have been rising for 50 million years due to the collision between the Indian and Eurasian tectonic plates. However, recent findings suggest that Everest’s growth is accelerating.

Credits: Reuters

The research, led by geoscientist Jin-Gen Dai from China University of Geosciences in Beijing, attributes this phenomenon to changes in the regional river system.

Approximately 89,000 years ago, the Kosi river merged with the Arun river, triggering increased erosion and reducing the weight on the Earth's crust.

This process, known as isostatic rebound, has caused Everest to rise by an estimated 49-164 feet (15-50 meters).

Isostatic rebound occurs when the Earth's crust, relieved of pressure from eroded material, rises in response. This geological process accounts for around 10% of Everest’s annual uplift rate, which translates to approximately 0.01-0.02 inches (0.2-0.5 millimetres) per year, a rate that outpaces ongoing surface erosion from wind, rain, and river flow.

Credits: NASA

The study also highlights that neighbouring peaks, including Lhotse and Makalu, are experiencing similar uplift. Makalu, closer to the Arun river, has an even higher uplift rate than Everest.

Adam Smith, a co-author of the study from University College London, noted that GPS data confirms Everest's continuous rise, a process that may further accelerate as erosion continues. The findings emphasise the dynamic nature of the Earth and show how even iconic natural features are constantly evolving.

This research serves as a reminder that the Earth is in a constant state of change, with many processes happening imperceptibly over time.