Glacier Hazards in the Himalaya-Karakoram

Abstract:

The melt water discharge from Himalaya-Karakoram (H-K) glaciers is of interest for irrigation and hydropower generation. However, they also pose substantial glacier hazards down into Plains areas. Major threats include glacier advances and retreat, avalanches, debris flow, glacial dams and glacial lake outburst floods (GLOFs). These hazards and changes observed and anticipated due to global climate change, affect and raise uncertainties concerning glacial environments. Specifically, Karakoram ice exhibits irregular behavior, largely related to a combination of Westerly and Monsoonal snow inputs and concentrations of surge-types glaciers whose behavior, hazards, and response to climate change differ from most other glaciers. Unlike other parts of the Himalaya, total ice mass has remained stable and may indicate a slight increase since the 1970s. In this study, we addressed these seeming anomalies through a comprehensive mapping of surge-type glaciers and surge-related impacts using multiple satellite images, DEMs, ground observations, and archival material since the 1840s. Surge cycle timing, intervals and mass transfers are unique to each glacier and largely out-of-phase with climate. We also identified ~150 floods from ice-dammed lakes which were mainly generated by advancing and surge-type glaciers. These results differ from Central and Eastern Himalayan glaciers that show exceptional rates of ice loss in recent decades due to warming and reductions in summer monsoon snowfall and/or increased black carbon deposits. Although glacier retreat in Himalaya has been destabilizing proglacial areas and generating unstable moraine-dammed lakes and subsequent GLOFs, the Karakoram region has observed additional threats due to surge induced ice-dam failure. Therefore, monitoring of H-K glaciers is essential for water resource planning and hazard mitigation in South-Central Asia. Remarkably, monitoring them remains a major challenge, which we also intend to discuss here.