Arching over 8,849 meters (29,032 ft) into the sky, Mount Everest is the world’s tallest mountain. But will it always hold this title? The mighty Himalayas, home to Everest and other towering peaks, are far from static. Over millennia, Everest has been growing – and shrinking. But where does this journey lead?
In April 2019, Aurora Elmore, a geologist and senior program manager for the National Geographic Society, was flying towards Everest’s South Base Camp. Rather than trekking the usual 12-day route through the Nepalese wilderness, she was aboard a helicopter, its rotor blades cutting through the thin mountain air. Below, the snow-covered peaks of the Himalayas sparkled under a cloudless sky.
Elmore was delivering supplies to scientists conducting research for a National Geographic and Rolex expedition studying climate change’s effects on the region. Over two months, the team collected data from the world’s highest weather station and made an alarming discovery: the highest evidence of microplastic pollution in snow and water near Everest’s summit. As Elmore’s helicopter ascended, she glimpsed a bustling sea of colorful tents at Everest Base Camp. Thousands of climbers had gathered, all hoping to conquer the world’s tallest mountain.
But unbeknownst to most of those climbers, Mount Everest was growing even as they scaled its heights.
Mount Everest rises slowly each year, thanks to the relentless movement of the Earth’s tectonic plates. The entire Himalayan range, including Everest, is pushed upwards by about 4 millimeters annually. This small but significant rise raises an intriguing question: Just how tall can Mount Everest get? Could it one day dwarf even the tallest mountains in our solar system, like Olympus Mons on Mars, which rises 21 kilometers (13 miles) into the Martian sky?
At present, Mount Everest stands at 8,848.86 meters (29,032 ft), based on a joint 2020 survey conducted by Nepal and China. It is not alone in its grandeur. Ten of the world’s 14 peaks higher than 8,000 meters (26,247 ft) are found in the Himalayan range. Despite the presence of other colossal mountains, Everest remains the undisputed king. As Elmore notes, “It’s like trying to tell the tallest person on a basketball team – they’re all tall, but Everest is the teeny bit taller.”
However, measuring Everest’s height has been a challenge over the centuries. The first recorded attempt came in 1852, when Indian mathematician Radhanath Sikdar used trigonometry to calculate Everest’s height. His figure, 8,839.8 meters (29,002 ft), was only 9 meters off the most recent measurements made with modern technology. While scientific advances have refined these measurements, disputes over whether to include the snow cap in Everest’s height have added to the complexity.
Politics has also played a role. In 2005, China measured Everest’s height at 8,844.43 meters (29,017 ft), excluding the snow cap. In contrast, Nepal traditionally included the snow in its measurements. The 2020 agreement between the two nations set the new official height at 8,848.86 meters, including the snow cap.
Yet, while humans debate Everest’s precise height, the mountain continues its slow, upward climb, driven by forces deep within the Earth.
Everest’s growth can be traced back to a monumental event 200 million years ago, when the supercontinent Pangea began to break apart. The Indian subcontinent, once nestled against Africa, started drifting northwards across the Tethys Ocean. For 150 million years, it inched closer to Asia until, around 45 million years ago, the two landmasses collided. The force of this collision crumpled the Earth’s crust, pushing what was once the ocean floor skywards.
Everest, along with the rest of the Himalayas, began its slow ascent towards the heavens. Around 17 million years ago, Everest’s summit reached 5,000 meters (16,404 ft). Today, the Indian plate continues to slide beneath the Eurasian plate, pushing Everest upwards by about 4 millimeters per year.
But Everest’s growth is not just a straightforward upward journey. The mountain is also constantly being worn down by erosion.
To understand the complex relationship between tectonics and erosion, scientists often look at other mountain ranges. One such range is the Saint Elias Mountains, which straddles the border between Alaska and Canada. Rachel Headley, an associate professor of geosciences at the University of Wisconsin-Parkside, has studied this region extensively. She and her team discovered that glaciers, rivers, landslides, and avalanches constantly erode the mountains, shaving away at their height.
Glaciers, in particular, play a critical role in erosion. As glaciers slide over rock, they act like a giant sandpaper, scraping away at the surface. This process, known as glacial abrasion, can significantly reduce a mountain’s height over time. In the case of Mount Saint Elias, weather patterns contribute to the growth of glaciers, which in turn accelerate erosion.
Mount Everest is also subject to these forces. While permanent snow caps protect the rock from erosion, the mountain still suffers from landslides, avalanches, and rockfalls. Rivers cutting through the rock around Everest are estimated to erode the mountain by 4-8 millimeters each year, almost counterbalancing its annual upward push.
Global warming adds another layer of complexity to the fate of Mount Everest. Aurora Elmore’s 2019 expedition revealed that the snow and ice on Everest are thinning at an alarming rate. As the ice recedes, more rock is exposed to the elements, accelerating erosion. As snow and ice disappear, they leave Everest vulnerable to the wind, which can hurl rocks and debris with destructive force.
Elmore’s team also found that climate change is altering the very structure of Everest’s glaciers. The thinning ice can weaken the rock, making it more prone to landslides and rockfalls. Additionally, the melting of glaciers contributes to glacial isostatic rebound, a process where the Earth’s crust rises after being compressed by glaciers during the ice age. This rebound could contribute an extra millimeter or more to Everest’s height each year.
Given the complex forces acting on Everest, accurately measuring its height is no easy task. One of the most advanced tools used today is the Global Navigation Satellite System (GNSS), which relies on a network of satellites to pinpoint the mountain’s exact height with millimeter precision. However, using GNSS on Everest presents unique challenges. The equipment is heavy, and the cold, thin air at the summit can interfere with both the devices and the people operating them.
In 2019, a Nepalese team spent two hours on Everest’s summit using GNSS to measure its height. They had to brave freezing temperatures and high winds, all while ensuring their instruments remained stationary long enough to gather accurate data. Another method, Ground Penetrating Radar (GPR), was used to measure the thickness of the snow and ice on Everest’s summit. This lightweight, specialized device had previously been tested on Denali, the tallest mountain in North America, proving it was up to the task.
Despite these technological advancements, Everest’s height remains fluid. Earthquakes, like the one that struck Nepal in 2015, can shift the mountain’s position. Following that earthquake, scientists found that Everest had moved 3 centimeters (1.2 inches) to the southwest, though its height remained unchanged.
So, will Everest continue to grow? The short answer is yes – for now. As long as the Indian plate keeps pushing against the Eurasian plate, Everest will continue its gradual ascent. However, erosion will limit how tall the mountain can get. Scientists believe that a delicate balance exists between tectonic uplift and erosive forces. In regions with active tectonics, like the Himalayas, this balance determines a mountain’s ultimate height.
Everest is not the fastest-growing mountain on Earth. Nanga Parbat, located in Pakistan, is growing at a rate of 7 millimeters per year. In theory, Nanga Parbat could overtake Everest in about 240,000 years. However, erosion may slow this process, keeping Everest at the top.
As scientists continue to measure and study Mount Everest, its allure remains undiminished. The mountain represents the pinnacle of human endurance and ambition. For those who reach its summit, like mountaineering journalist Billi Bierling, who climbed Everest in 2009, the exact measurement of its height is secondary to the experience itself.
Whether Everest grows taller by a few millimeters or a few meters, it will always hold a special place in the hearts of adventurers. For Bierling, as for many others, it is not just about reaching the highest point on Earth but about the journey it represents. “If you’re having a bad day,” she says, “you can think to yourself, you know what? I’ve climbed Everest.”
Mount Everest is more than just a mountain. It is a symbol of Earth’s raw power, constantly growing and changing in the face of forces both natural and human-made. As we look to the future, one thing is certain: Everest will continue to captivate, inspire, and challenge us for generations to come.
