Although they are true colossi, the highest peaks in the Himalayas are very close in height, with one exception. Mount Everest is an anomaly; it towers over its neighbors by hundreds of meters, and recent research has finally revealed the cause of this unusual height.
in the Himalayas. With an impressive elevation of 8,849 meters, Everest (known as Chomolungma in Tibetan or Sagarmāthā in Nepali) is 238 meters higher than K2.
According to the authors of the new study, this discrepancy is clearly meaningless, “given the relative uniformity of , which is characterized by mountain peaks with small-scale local variability and relatively uniform climatic conditions and erosional processes.”
Consequently, the next four highest peaks after Everest are separated by a total difference of only about 120 meters. Mount Everest’s extraordinary size therefore appears to be a significant anomaly, which the researchers believe can be explained by a network of high-altitude rivers forcing Everest’s summit to rise by a few millimeters per year.
Mount Everest is an anomaly
“Mount Everest is a remarkable mountain, steeped in myth and legend, and it continues to grow. Our research shows that as the nearby erodes deeper, the loss of material causes the mountain to rise further,” said study author Adam Smith.
The culprit appears to be the Arun River, which runs past the mountain to the east before joining the larger Kosi River. Over the millennia, Arun carved a deep valley through the heart of the Himalayas, removing billions of tons of rock.
The erosion of such colossal amounts of material triggered a process called isostatic compensation, whereby the enormous pressure of the Earth’s liquid mantle, pushing up from beneath the crust, gains ground in the face of the diminished weight of the soil. This process, in turn, seems to fuel Everest’s steady growth.
“The interaction between the erosion of the Arun River and the upward pressure of the Earth’s mantle gives Mount Everest a boost, lifting it higher than it would normally be,” explained study author Dr. Xu Han, .
Everest is growing 2 millimeters a year
By calculating the erosion rates of several watercourses in the network, the study authors found that the Arun River joined the Kosi about 89,000 years ago. This merger increased the magnitude of the isostatic offset, allowing greater amounts of soil and sediment to be washed downstream on the Kosi River, a phenomenon known as “drainage piracy”.
As a result, Everest is currently rising by about 2 millimeters a year, and researchers estimate that the mountain has gained between 15 and 50 meters in height since the two rivers joined. Other peaks in the region, such as Lhotse and Makalu, have also raised their summits due to the same isostatic compensation, thus rising to the fourth and fifth places in the ranking of the highest mountains measured from sea level.
The study was published in the journal
