Recent uplift of Chomolungma enhanced by river drainage piracy

Abstract

The Himalayas, which host glaciers, modulate the Indian Monsoon and create an arid Tibetan Plateau, play a vital role in distributing freshwater resources to the world’s most populous regions. The Himalayas formed under prolonged crustal thickening and erosion by glaciers and rivers. Chomolungma (8,849 m)—also known as Mount Everest or Sagarmāthā—is higher than surrounding peaks, and GPS measurements suggest a higher uplift rate in recent years than the long-term trend. Here we analyse the potential contribution of a river capture event in the Kosi River drainage basin on the renewed surface uplift of Chomolungma. We numerically reconstruct the capture process using a simple stream power model combined with nonlinear inverse methods constrained by modern river profiles. Our best-fit model suggests the capture event occurred approximately 89 thousand years ago and caused acceleration of downstream incision rates. Flexural models estimate this non-steady erosion triggers isostatic response and surface uplift over a broad geographical area. We suggest that part of Chomolungma’s anomalous elevation (~15–50 m) can be explained as the isostatic response to capture-triggered river incision, highlighting the complex interplay between geological dynamics and the formation of topographic features. The recent uptick in surface uplift of Chomolungma (Mount Everest) can be partly attributed to isostatic rebound due to increased erosion following a river capture event, according to river evolution and flexural modelling.