Reply on RC2

Abstract

Surges are an important source of glacier hazards and complete surge-type glacier inventories are required for assessing glacier-related hazards. Glacier surge events in High Mountain Asia (HMA) are widely reported. However, the completeness of present inventories of HMA surge-type glaciers is constrained by the insufficient spatial and temporal coverage of glacier change observations, or by the limitations of the identification methods. In this paper, we established a new inventory of HMA surge-type glaciers based on the glacier surface elevation changes over four decades. Four kinds of elevation sources (KH-9 DEM, NASADEM, COP30 DEM, HMA8m DEM) were utilized to estimate the glacier surface elevation changes during two periods (1970s–2000 and 2000–2010s). In total 1015 surge-type glaciers were identified in HMA. Compared to the latest surge-type glacier inventory in HMA, our inventory incorporated 477 new surge-type glaciers. The number and area of surge-type glaciers accounted for ~2.49 % (excluding glaciers less than 0.3 km2) and ~23.32 % of the total glacier number and glacier area in HMA, respectively. Considering that glacier outlines are usually composed of multiple tributaries within a glacier complex, the proportion of surge-related area may be overestimated, and the number of surge-type glaciers could be even larger. Surge-type glaciers were found in 21 of the 22 subregions of HMA (except for the Dzhungarsky Alatau), however, the density of surge-type glaciers is highly uneven. Surge-type glaciers are common in the northwest subregions (e.g., Pamir and Karakoram), but scarce in the peripheral subregions (e.g., Eastern Tien Shan, Eastern Himalaya, and Hengduan Shan). The inventory indicates that surge activity is more likely to occur for larger and longer glaciers. Besides, we found a potential relationship between the frequency of surge activities andregional glacier mass balance. The subregions with slightly negative or positive mass balance hold large clusters of surge-type glaciers, while those with severe glacier mass loss hold very few surge-type glaciers. In some subregions where glacier mass loss accelerated, the frequency of surge activities that occurred before 2000 was much higher than that after 2000. The inventory is available at: https://doi.org/10.5281/zenodo.6944979 (Guo et al., 2022).