Climate-driven topographic asymmetry enhanced by glaciers: Implication for divide stability in glacial landscapes

Climate contrasts across drainage divides, such as orographic precipitation, are ubiquitous in mountain ranges, and as a result, mountain topography is often asymmetric. Asymmetric glaciation arising from climate gradients across divides can cause topographic asymmetry that is potentially different from fluvial landscapes, causing divide instability during glacial-interglacial cycles. In this study, we quantified topographic asymmetry caused by asymmetric glaciation and assessed its sensitivity to different climate scenarios. Using an analytical model of a steady-state glacial profile, we find that the degree of topographic asymmetry is primarily controlled by differences in the Equilibrium Line Altitude (ELA) across the divide. When the ELA differences are caused by precipitation variations across the divide, glacial topography exhibits greater asymmetry than fluvial topography. These results suggest that glacial erosion responds differently to the same climate asymmetry from fluvial erosion, and therefore, intermittent glaciations may have promoted drainage reorganization and landscape transience in glaciated mountain ranges. Preliminary model results indicate that the rate of divide migration caused by asymmetric glaciation is several millimeters per year and the timescale of migration is several million years.