Modelling supraglacial debris-cover evolution from the single-glacier to the regional scale: an application to High Mountain Asia

Abstract. Currently, about 12 %–13 % of High Mountain Asia’s glacier area is debris-covered, which alters its surface mass balance. However, in regional-scale modelling approaches, debris-covered glaciers are typically treated as clean-ice glaciers, leading to a bias when their future evolution. Here, we present new approach for debris and thickness evolution, applicable from single the global scale. We derive parameterization implement it module into Global Glacier Evolution Model (GloGEMflow), combined mass-balance ice-flow model. The initialized with both glacier-specific observations debris' spatial distribution estimates thickness. These data sets account fact that can either enhance or reduce melt depending on Our model also enables representing spatiotemporal evolution extent calibrate evaluate selected subset apply GloGEMflow using different climate scenarios project all Asia until 2100. Explicitly accounting cover has only minor effect projected loss, line previous projections. Despite this small effect, argue improved process representation added value aiming at capturing intra-glacier scales, i.e. distribution. Depending scenario, mean debris-cover fraction expected increase, while show changes, although large local thickening expected. To isolate influence explicitly supraglacial cover, re-compute without module. geometry, area, volume, flow velocity evolve differently, especially level individual glaciers. This highlights importance projecting changes.