Glacier Change, Concentration, and Elevation Effects in the Karakoram Himalaya, Upper Indus Basin

This paper seeks to explain evidence of distinctive late- and post-Little Ice Age glacier change in the Karakoram Himalaya and a recent, seemingly anomalous, expansion. Attention is directed to processes that support and concentrate glacier mass, including an all-year accumulation regime, avalanche nourishment, and effects related to elevation. Glacier basins have exceptional elevation ranges, and rockwalls make up the larger part of their area. However, more than 80% of the ice cover is concentrated between 4000 and 5500 m elevation. Classification into Turkestan-, Mustagh-, and Alpine-type glaciers is revisited to help identify controls over mass balance. Estimates of changes based on snowlines, equilibrium line altitudes, and accumulation area ratio are shown to be problematic. Extensive debris covers in ablation zone areas protect glacier tongues. They are relatively insensitive to climate change, and their importance for water supply has been exaggerated compared to clean and thinly covered ablation zone ice. Recent changes include shifts in seasonal temperatures, snowfall, and snow cover at high elevations. Understanding their significance involves rarely investigated conditions at higher elevations that lack monitoring programs.