Glaciological and hydrological sensitivities to climate change in the Hindu-Kush Himalayas

Abstract:

The impact of climate change on glaciers will affect the timing and magnitude of water availability from high-altitude catchments in the Hindu-Kush Himalaya (HKH) region. In this study, we quantify the current sensitivity of glacier systems to climatic change and the associated sub-basin hydrological sensitivity throughout the HKH region using glacier inventory data and high-resolution dynamically downscaled climate fields. We first estimate the glaciological sensitivity, or change in glacierized area with change in equilibrium line altitude (ELA), for each sub-basin using a glacier inventory and SRTM DEM. We assign a climatic sensitivity of the ELA to temperature changes (dELA/dT) based on published values for tropical and sub-tropical glaciers and a high-resolution annual precipitation field. To assess the change in glacier meltwater contribution as a result of warming, we first estimate baseline glacier meltwater contributions using a mass balance gradient and estimated current ELA. Future climate warming scenarios of +1K and +2K are then used to examine the change in glacier meltwater contributions based on the increased ELA and ablation area. Finally, we calculate a glacier significance index that examines the relative importance of melt within each sub-basin, and discuss regional variations in glacier sensitivity and significance.