World map highlighting Mt. Everest on the Nepal-China border

Jim McMahon/Mapman®

Climbers scaling Mount Everest will have a little farther to go to reach the top in the future. That’s because the world’s tallest mountain is getting even taller.

Everest, with a height of 29,032 feet tall, is part of the Himalayas in Asia. Those mountains grow over time because of tectonic plate movement. That growth adds up to about 2 millimeters each year. But scientists say that doesn’t fully explain how fast Everest is growing. Over the past tens of thousands of years, Everest has grown about 50 to 164 feet more than expected!

Computer models recently helped scientists better understand the increase. About 89,000 years ago, two major river systems merged roughly 50 miles from Everest. The joining created a powerful force of water that washed away a massive amount of rock and mud. The erosion was so great, it reduced the weight of Earth’s crust near the peak, allowing the land to lift upward. (Think of a boat rising after cargo is unloaded.)

That event still affects Everest today—to the tune of an extra 0.2 to 0.5 millimeters a year. It may also help explain why Everest is nearly 800 feet taller than its neighbors.

—Lisa M. Herrington