Updated Surge‐Type Glacier Inventory in the West Kunlun Mountains, Tibetan Plateau, and Implications for Glacier Change

Abstract

Glacier surging is a dynamic instability that affects the flow of some glaciers, modifying the glacier area, surface velocity, and surface elevation. It is also among the major causes of ice dams and glacier lake floods. Previous studies have shown that in the West Kunlun Mountains| (WKM) where a cluster of surge‐type glaciers had been found, the glaciers were relatively stable in recent years. Nevertheless, the surge cycle and its impact on glacier changes on a regional scale are poorly understood. In this study, we updated the surge‐type glacier inventory of the WKM using the detailed changes in glacier length, surface velocity, and surface elevation during the 1972–2020 period using 78 Landsat optical images, 86 Sentinel‐1 synthetic aperture radar (SAR) images, and three digital elevation models of the WKM. The updated results show that among the 423 glaciers in the WKM, 10 are confirmed as surge‐type glaciers, three are likely surge‐type glaciers, and five are possible surge‐type glaciers. Furthermore, these 18 glaciers account for 63% of the total glacier area. During the period analyzed, there were marked changes in the lengths, areas and surface elevations of all surge‐type glaciers, while those of the non‐surge‐type glaciers were relatively stable. These results appear to indicate that the observed regional trends of glaciers in the WKM recently may be related to the existence of surge‐type glaciers. Furthermore, the surge‐type glacier underwent advance after accelerating for 3–4 years, which could be used to forecast when glacier termini may advance and avoid the possible catastrophic damages.

Possible Causes of Anomalous Glacier Mass Balance in the Western Kunlun Mountains

“…For example, some glaciers presented short‐term (one or several years) advances within a retreating trend during 1972–2020, while some exhibited a continuous advance or continuously retreated (Guan et al., 2022). However, most glaciers (about 405, including large and small glaciers and Guliya) in the WKM had a relatively stable terminus position, with total variations of <0.12 km during 1972–2020 (Guan et al., 2022). Thus, our assumption that ice‐covered areas on Guliya did not change during 1970–2019 is reasonable.…”

“…The spatial‐temporal patterns of glacier velocities in the WKM are complicated. The velocities in the centerline within the ablation zone of some glaciers were larger in summer (∼0.3 m d −1 ) compared to those in winter (<0.05 m d −1 ) during 2017–2019, while the velocities of some glaciers were faster during winter than during summer (Guan et al., 2022). For surge‐type glaciers, Yasuda and Furuya (2015) found that the surface velocity is faster in early winter than in summer because of the presence of surface meltwater that reroutes through the englacial and subglacial drainage.…”

“…For surge‐type glaciers, Yasuda and Furuya (2015) found that the surface velocity is faster in early winter than in summer because of the presence of surface meltwater that reroutes through the englacial and subglacial drainage. On interannual timescales, some large glaciers in the WKM showed variable changes in surface velocities (acceleration, deceleration, and relative stability) in different periods during 1991–2020, although most glaciers in the WKM had slow velocities with little variation (Guan et al., 2022). For example, the modeled mean annual horizontal ice flow speeds of Guliya were relatively low (less than 20 m/a), and the ice flow velocities on the terminus and the ablation zone were lower compared to those in the accumulation zone (W. Chen et al., 2017).…”

“…If surge‐type glaciers increase the glacier area at low altitudes, glacier ablation will increase, leading to more mass loss. However, the initiation time and duration of the active phase of glacier surging varied greatly for different glaciers in the WKM (Guan et al., 2022). It is difficult to estimate the influence of glaciers surging on changes in regional glacier mass balance on interdecadal timescales.…”

“…It is difficult the influence of glaciers surging on changes regional glacier mass balance on interdecadal timescales. Guan et al (2022) found that glaciers in the WKM were divided into one of four categories: seven confirmed surge-type glaciers, one likely surge-type glacier, eight possible surge-type, and 407 non-surge-type glaciers. Therefore, most WKM glaciers were relatively stable without discernible surging.…”