Glacier mass balance and its potential impacts in the Altai Mountains over the period 1990–2011

The Altai Mountains contain 1281 glaciers covering an area of 1191 km². These glaciers have undergone significant changes in glacial length and area over the past decade. However, mass changes of these glaciers and their impacts remain poorly understood. Here we present surface mass balances of all glaciers in the region for the period 1990–2011, using a glacier mass-balance model forced by the outputs of a regional climate model. Our results indicate that the mean specific mass balance for the whole region is about −0.69 m w.e. yr⁻¹ over the entire period, and about 81.3% of these glaciers experience negative net mass balance. We detect an accelerated wastage of these glaciers in recent years, and marked differences in mass change and its sensitivity to climate change for different regions and size classes. In particular, higher mass loss and temperature sensitivity are observed for glaciers smaller than 0.5 km². In addition to temperature rise, a decrease in precipitation in the western part of the region and an increase in precipitation in the eastern part likely contribute to significant sub-region differences in mass loss. With significant glacier wastage, the contribution of all glaciers to regional water resources and sea-level change becomes larger than before, but may not be a potential threat to human populations through impacts on water availability.