Mount Everest is getting TALLER by the day: World’s highest mountain has grown by up to 164ft over the past 89,000 years – and there’s an unusual reason why

At 8,849 meters (29,032 feet), reaching the summit of Mount Everest has long been considered one of mountaineering’s greatest challenges.

However, the climbers of the future could face even more challenges as experts reveal the world’s highest mountain is growing by the day.

Researchers from University College London found that Mount Everest has already grown between 15 and 50 meters (49-164 ft) over the past 89,000 years.

They claim that this unexpected growth spurt is due to a nearby river eroding so much material that the mountain is becoming lighter and springing up at a rate of 2 mm per year.

Co-author Adam Smith says: ‘Mount Everest is a remarkable mountain of myth and legend and still growing.’

At 8,848 meters (29,032 feet), Mount Everest is the world’s tallest mountain, but researchers now say it is growing even taller, at 2 mm per year

In general, the largest peaks within a mountain range are all about the same size and vary perhaps by a few hundred meters at most.

Mr Smith told MailOnline: ‘Everest is 250 meters higher than K2, the second highest peak in the world, but K2 and the other peaks are only 50-100 meters higher than the next highest peaks. In that sense, Everest is an anomaly.’

Not only is Everest unusually tall, but scientists now know that it is getting taller every year.

GPS instruments show that Everest’s peak is rising at about 2 mm per year.

But so far there’s no clear explanation for why Everest is so much bigger than its companions, or how it continues to grow.

The answer, as the researchers write in Nature Geoscience, actually has nothing to do with Everest itself, but comes down to the action of a nearby river.

Co-author Dr. Jin-Gen Dai says: ‘There is an interesting river system in the Everest region: the upstream Arun River flows east at high altitude with a flat valley.

Researchers have found that river erosion (shown in orange) around Everest, here called Chomolungma by its Tibetan name, is causing the mountain to rise higher every year.

89,000 years ago, the gentle River Arun merged with the steep River Kosi (pictured), vastly increasing its erosive force and allowing billions of tons of rock and sediment to be removed from the area around Mount Everest

‘It then turns abruptly south like the Kosi River, drops in height and becomes steeper.’

By studying the erosion rates of rivers in the region, Dr. Dai and his colleagues that these two rivers, the Arun and the Kosi, merged about 89,000 years ago.

When this happened, much more water was diverted down the steep, narrow Kosi River, dramatically increasing its erosive power.

While this may not be apparent on the human time scale, over thousands of years this has led to the removal of billions of tons of rock and sediment from the area around Everest.

Slowly, this enlightenment process means that Everest is literally floating upwards through a process called ‘isostatic rebound’.

Mount Everest (photo) is about 250 meters higher than the next highest mountains. Researchers now think this may be due to the effects of the nearby river systems

As the Arun and Kosi Rivers erode material around the mountains, they become lighter and float higher on the liquid mantle beneath the Earth’s crust. This map shows how areas of high erosion (red) are located near Everest (Chomolungma) and Makalu mountains

Mr Smith explains: ‘The crust, the outermost layer of the Earth, ‘floats’ on the mantle, a semi-liquid layer beneath the crust.

‘This is similar to how icebergs float on water.

‘The lighter or less dense a material is, the higher it floats in water or on the mantle.’

Mr. Smith says you can think of the area around Mount Everest as a float on the surface of the water.

If you place weights on the float, gravity will be stronger than the force of the water pushing up and the float will sit lower in the water.

But if you gradually take some of those weights off, you will notice that the float gradually rises.

“This has happened to Everest because material close to Everest has been removed, causing an uplift or isostatic recovery,” Mr Smith added.

A process called isostatic rebound may explain why Everest is significantly higher than the other peaks in the Himalayas (pictured)

This diagram shows the areas of highest (top) and lowest (bottom) elevation in the Himalayas. You can see that the highest points of Chomolungma (Everest) and Kanchenjunga are closest to the low point of the Kosi River

In the 89,000 years since the Kosi and Arun rivers merged, they have removed enough weight to lift Everest somewhere between 15 and 50 meters, researchers say.

Because the material is removed so close to Everest, the team thinks this could be one of the reasons Everest is so much higher than peaks like K2.

But although the mountains will continue to grow taller for the time being, this process will eventually reach its limit.

Mr Smith added: ‘Everest can’t keep growing forever.

“I think the height of Everest is limited by the strength of the rocks and the amount of material or rock we have available to make the mountain, which is finite.”

However, Everest is not the only mountain in the rage that is increasing in size, as the isostatic rise affects all nearby mountains.

The fastest growing mountain in the range is Makalu, the fifth highest mountain in the world at 8,485 meters (27,766 ft), which has risen 60 meters (197 ft) since the rivers merged.

However, Mr Smith does not believe the difference is big enough for Makalu to overtake Everest as the world’s highest mountain.