Mount Everest is still growing. The same tectonic collision that built the Himalayas tens of millions of years ago continues today, with the Indian plate pushing into Eurasia at roughly two centimeters per year. But the story is more interesting than simple plate tectonics would suggest. A 2024 study in Nature Geoscience identified a second, less obvious mechanism: a river capture event that has been giving Everest an additional boost for the last 89,000 years or so, potentially adding between 15 and 50 meters to its peak elevation.
The Collision That Built the Roof of the World
The Himalayas exist because India is crashing into Asia, and that crash has not stopped. The Indian subcontinent, once an island landmass drifting northward, began colliding with the Eurasian plate around 50 million years ago. That collision crumpled, folded, and thrust enormous slabs of rock upward, eventually producing the highest mountain range on Earth. The forces driving this process are still active.
GPS measurements across the Nepal Himalaya show that the Indian plate is converging with southern Tibet at about 20 millimeters per year, based on six years of satellite data that constrain the maximum surface contraction rate to roughly 18 millimeters per year across the deforming zone.1Journal of Geophysical Research: Solid Earth. Kinematics of the India‐Eurasia collision zone from GPS measurements A separate analysis using GPS observations arrived at a present-day convergence rate of about 22 millimeters per year, consistent with geological estimates of 18 millimeters per year for the past two to three million years.2Chinese Journal of Geophysics. A Study on Convergence Rate of the India to Eurasia Subduction Beneath Qinghaixizang Plateau—‐Inversion Results from Gps Observational Data The agreement between modern satellite data and longer geological records suggests this convergence has been remarkably stable over millions of years.
Not all of that two-centimeters-per-year convergence translates into upward growth at the summit, though. Much of the crustal shortening is absorbed by deformation spread across a wide zone, by thrust faulting at depth, and by the thickening of the Tibetan Plateau behind the Himalayas. The actual rate at which Everest’s summit gains elevation from tectonic forces alone is far slower than the plate convergence rate, likely on the order of a few millimeters per year. Still, over geological time, even a few millimeters each year adds up.
The River That Made Everest Taller
In 2024, researchers published a finding that added an unexpected wrinkle to the story of Everest’s growth. A team analyzing the Kosi River drainage basin, which wraps around the Everest massif, found evidence that a river capture event roughly 89,000 years ago has been contributing to the mountain’s rise through a process called isostatic rebound.3Nature Geoscience. Recent uplift of Chomolungma enhanced by river drainage piracy
River capture, sometimes called stream piracy, happens when one river system erodes headward and intercepts the flow of a neighboring drainage. When the Kosi system captured a tributary, it dramatically increased the volume of water flowing through its channels, which in turn accelerated the rate at which the river carved into the landscape. More rock was removed from the surrounding valleys, and faster than before.
This is where isostatic rebound comes in. Earth’s crust floats on denser, semi-fluid rock beneath it. When you remove weight from the surface by eroding away rock, the crust responds by rising, much like a boat rises in water when you offload cargo. The accelerated erosion from the river capture event effectively unloaded material from around Everest’s base, and the crust beneath the mountain bobbed upward in response. The researchers’ flexural models estimate that this mechanism could account for roughly 15 to 50 meters of Everest’s current elevation, and the uplift extends over a broad geographical area.3Nature Geoscience. Recent uplift of Chomolungma enhanced by river drainage piracy
This finding matters because geologists have long puzzled over why Everest stands so much higher than neighboring peaks that are subject to the same tectonic forces. The peaks around it, like Lhotse and Makalu, are also pushed up by the India-Eurasia collision, yet Everest towers above them by a significant margin. The river capture mechanism offers a partial explanation: Everest got a localized boost that its neighbors did not, or at least not to the same degree. The interplay between river erosion and crustal response turns out to be one of the reasons this particular mountain claimed the title of highest point on Earth.
When Earthquakes Push the Mountain Down
If tectonic forces and isostatic rebound are pushing Everest up, earthquakes periodically push it down. The devastating 2015 Gorkha earthquake in Nepal, which measured magnitude 7.8, caused widespread subsidence across parts of the Himalayan region. Satellite measurements after the quake showed that the area around Everest dropped by a small amount as the accumulated tectonic strain was suddenly released. The earthquake effectively relaxed the compression that had been building up along the fault system, causing the surface to settle.
This is not unique to the 2015 event. Major earthquakes in subduction and collision zones routinely cause nearby peaks to lose a few centimeters or even meters of elevation. The 2015 quake prompted a joint Chinese-Nepalese resurvey of Everest, which in 2020 yielded the current official height of 8,848.86 meters, slightly higher than the previously accepted figure. Whether the quake itself caused a net loss at the very summit remains debated, partly because measuring summit elevation to centimeter precision involves its own challenges.
Over the long run, earthquakes and tectonic uplift are two sides of the same coin. The strain builds gradually between earthquakes as the plates converge, and then some of that stored energy is released suddenly during a quake. The net effect, averaged over thousands of years, is still upward growth, because the tectonic forces pushing the range up are ongoing and the earthquakes only partially undo the accumulated rise.
The Problem With Measuring a Mountain
Saying Everest is 8,848.86 meters tall sounds precise, but the number hides considerable complexity. Different surveys over the decades have produced different values, and not just because the mountain is moving. The challenges are partly technical and partly about what you are actually measuring.
One fundamental issue is defining “sea level.” Everest is thousands of kilometers from the nearest ocean, so its height above sea level is calculated relative to a mathematical model of Earth’s gravity field called the geoid. The accuracy of this calculation is limited to roughly plus or minus two meters, depending on how well the geoid is modeled in that region.4Journal on Geoinformatics, Nepal. Concept in Determining the Height of Mount Everest (Sagarmatha) That means even with perfect GPS readings at the summit, the height “above sea level” carries an inherent uncertainty of a couple of meters from the geoid model alone. This is why different national surveys, using slightly different geoid models, have arrived at slightly different official heights.
Then there is the question of snow. The summit of Everest is not bare rock; it is covered by a layer of snow and ice that varies in thickness with the seasons and from year to year. A ground-penetrating radar survey found a clear, gradual thickening of the snow layer along the north slope toward the summit, with a well-defined contrast between the snow surface and the underlying limestone.5The Cryosphere. Brief communication: How deep is the snow on Mount Everest? Whether the “height of Everest” refers to the snow surface or the rock surface matters. The 2020 joint survey measured the snow surface, which is what climbers actually stand on. If the snow cap thins significantly due to warming, the measured height could drop even if the rock beneath is still rising.
GPS technology has dramatically improved the precision of summit measurements compared to the optical trigonometric surveys of earlier decades. But precision and accuracy are different things. A GPS receiver on the summit can pinpoint its position to within centimeters, but converting that position to a height above sea level still depends on the geoid model, atmospheric corrections, and the duration of the GPS observation. The 2020 survey combined GPS data, trigonometric leveling, gravimetric geoid determination, and precise leveling to arrive at the current figure.4Journal on Geoinformatics, Nepal. Concept in Determining the Height of Mount Everest (Sagarmatha) Future resurveys will likely refine the number further, but tracking millimeter-scale tectonic growth against a backdrop of meter-scale measurement uncertainty remains genuinely difficult.
Is There a Ceiling for How Tall a Mountain Can Get?
If Everest is still growing, a natural follow-up question is whether it can keep growing indefinitely. It cannot. Several physical constraints impose an upper limit on mountain height, and Everest is probably already close to the practical ceiling for an Earth mountain.
The most straightforward constraint is gravity. A mountain is essentially a pile of rock, and the weight of that pile generates compressive stress at its base. The taller the mountain, the greater the stress. At some point, the rock at the base would be crushed under its own weight. The theoretical maximum depends on the rock’s compressive strength, its density, and the local gravitational acceleration.6Geomorphology. What is the maximum elevation mountains can reach on Earth, the Moon, and Mars? In practice, the flanks of a mountain provide lateral support that increases the effective strength of rock at the base, which is why real mountains can stand taller than a naive calculation of a freestanding column would predict.
A second constraint is isostasy itself. The same buoyancy effect that lifts Everest when surrounding rock is eroded also limits its growth. As a mountain gets taller, its mass pushes the crust deeper into the mantle, like loading more weight onto a raft. The lithosphere flexes downward beneath the mountain, which partially offsets the upward growth. This creates a natural feedback loop: the taller the mountain grows, the more the crust sinks beneath it, and the harder it becomes to gain additional elevation.6Geomorphology. What is the maximum elevation mountains can reach on Earth, the Moon, and Mars?
Erosion is the third major limit. Glaciers, rivers, freeze-thaw cycles, and landslides all work to tear mountains down. The higher a peak rises, the more aggressively it is attacked by weather and ice. In active mountain belts, there is a rough balance between tectonic uplift and erosion, and the topography tends toward a steady state where peaks grow and erode at similar rates over geological timescales. Everest exists in a zone where uplift currently outpaces erosion at the summit, but only slightly.
Interestingly, the maximum possible mountain height is much greater on bodies with lower gravity. Mars, with about 38 percent of Earth’s surface gravity, hosts Olympus Mons at roughly 21 kilometers, more than twice Everest’s height. The Moon, with even less gravity, could in theory support mountains taller still. On Earth, the combination of stronger gravity, active erosion, and lithospheric flexure keeps mountains in the single-digit-kilometer range.
Climate Change and the Shrinking Summit Ice
While the rock beneath Everest’s summit is rising, the ice and snow on top of it are under threat. Research on the South Col Glacier, the highest glacier on Everest at roughly 7,900 meters, has found that it is losing mass at an accelerating rate driven by changing climate conditions. A simulation covering 1950 to 2019 found that sublimation, the process by which ice turns directly into water vapor without melting, is by far the dominant mechanism of ice loss at that altitude, far outpacing surface melt. But both sublimation and melt have been trending upward. Sublimation increased at a rate of about 0.22 millimeters of water equivalent per year, and surface melt, while still small, also showed a significant upward trend.7npj Climate and Atmospheric Science. Mt. Everest’s highest glacier is a sentinel for accelerating ice loss
Rising air temperature plays a central role. As the surface warms, the moisture gradient between the ice surface and the dry atmosphere above it steepens, pulling more water vapor off the glacier. Declining relative humidity and strengthening winds amplify this effect. The researchers estimated cumulative mass loss of about 1,530 millimeters of water equivalent by the end of 2019, suggesting that even if the glacier was in balance in the mid-20th century, decades of climate change have driven considerable thinning.7npj Climate and Atmospheric Science. Mt. Everest’s highest glacier is a sentinel for accelerating ice loss
The South Col Glacier sits below the summit, but the same physics applies to the snow and ice cap at the top. If warming continues to thin the summit snowpack, the measured height of Everest could actually decrease in coming decades, even as the underlying rock continues its slow upward creep. This creates a paradox where the mountain is tectonically growing but potentially getting shorter as measured from the snow surface. Whether future surveys report a taller or shorter Everest may depend as much on the state of the summit ice as on geology.
How Fast Is Everest Actually Rising Right Now?
Pinning down a single annual growth rate for Everest is harder than it sounds, because different processes operate on different timescales and in different directions. The tectonic contribution, from the India-Eurasia convergence, is probably a few millimeters per year of net uplift at the summit after accounting for the fact that most of the plate convergence is absorbed elsewhere in the collision zone. GPS stations in the region confirm the plates are converging at roughly 18 to 22 millimeters per year,1Journal of Geophysical Research: Solid Earth. Kinematics of the India‐Eurasia collision zone from GPS measurements2Chinese Journal of Geophysics. A Study on Convergence Rate of the India to Eurasia Subduction Beneath Qinghaixizang Plateau—‐Inversion Results from Gps Observational Data but only a fraction of that shows up as vertical summit growth.
The isostatic rebound from river capture adds an additional component. Averaged over the roughly 89,000 years since the capture event, the 15 to 50 meters of estimated additional elevation works out to somewhere between 0.2 and 0.6 millimeters per year.3Nature Geoscience. Recent uplift of Chomolungma enhanced by river drainage piracy This is a rough average, and the actual rate likely varies as erosion patterns shift. Still, it represents a meaningful supplement to tectonic uplift.
Working against both of these is erosion, which removes rock from the summit and flanks, and earthquakes, which periodically drop the surface. The net effect of all these competing forces is that Everest is growing, but slowly, and the growth is punctuated by occasional setbacks. Over the next million years, absent a dramatic change in plate tectonics, Everest will likely continue to gain elevation gradually, though it will never run away to dramatically greater heights because the physical limits described earlier keep it in check.
Why Everest Uses a Different Name in Scientific Papers
Readers browsing the research literature will notice that many recent papers refer to Everest as “Chomolungma,” its Tibetan name, rather than “Mount Everest.” The 2024 Nature Geoscience river capture study, for example, uses “Chomolungma” throughout. In Nepal, the mountain is called Sagarmatha, and the Nepali government uses that name in its own surveys and publications.4Journal on Geoinformatics, Nepal. Concept in Determining the Height of Mount Everest (Sagarmatha) The name “Everest” honors George Everest, a 19th-century British Surveyor General of India who, somewhat ironically, never saw the mountain and objected to having it named after him. The shift toward indigenous names in scientific publications reflects a broader trend in geoscience, though “Everest” remains the most widely recognized name internationally and the one used by most mountaineering organizations. All three names refer to the same peak, the same GPS coordinates, and the same ongoing tectonic drama.