Increase in erosion rates of the Himalayas controlled by tectonics

Climatic and tectonic processes are thought to jointly influence topography and erosion rates, but their intertwined nature obscures their individual contributions. The Himalayas, one of the most tectonically active regions on Earth, serve as a focal point for studying how erosion rates are affected by tectonic activity and climate. Here we use a coupled numerical model of geodynamic deformation, erosion, and precipitation to quantify the contribution of tectonics and orographic precipitation on changes in erosion rates, providing a new perspective on this issue. By tracking rock trajectories from depth to surface, our models suggest a natural increase in erosion rates during Himalayan growth. This increase is fundamentally dictated by the evolving architecture of structural systems, which controls the trajectories of rocks as they are advected toward the surface. Initially, horizontal advection at the orogen margin drives slow exhumation, followed by upstream propagation of erosion caused by crustal thickening and uplift, which results in rapid exhumation. The modeled trend matches the observed pattern of accelerating exhumation and implies that such increases, inherent to crustal thickening and coeval landscape evolution, can occur independently of climate change.