Abstract
Abstract. The return periods of Karakoram glacier surges are poorly quantified. Here, we present evidence of an historic surge of the Khurdopin Glacier that began in the mid-1970s and peaked in 1979. Measured surface displacements reached >5 km a−1, two orders of magnitude faster than during quiescence. The Khurdopin Glacier next surged in the late 1990s, equating to a return period of 20 years. Surge evolution in the two events shows remarkable similarity suggesting a common trigger. Surge activity in the Karakoram needs to be better understood if accurate mass balance assessments of Hindu-Kush–Karakoram–Himalaya glaciers are to be made.
Highlights
Glaciers in the Karakoram experienced significant recession for the vast majority of the twentieth century, apart from some short-term advances during the 1970s (Hewitt, 2005)
We report on a previously undocumented surge of the Khurdopin Glacier that occurred in the late 1970s, detected in Landsat Multispectral Scanner (MSS) imagery
These data suggest that the thickening and thinning cycles on the lower Khurdopin Glacier previously reported by Mason (1930) were surge events taking place over an approximate cycle of 20 years
Summary
Glaciers in the Karakoram experienced significant recession for the vast majority of the twentieth century, apart from some short-term advances during the 1970s (Hewitt, 2005). Recent studies have quantified dramatic changes in Karakoram-wide glacier velocities (Heid and Kääb, 2012) and, have quantified individual surge magnitudes by tracking surface features between multitemporal satellite images (Quincey et al, 2011; Mayer et al, 2011). There is consensus, that surge events are increasing in the Karakoram, and that this is likely to reflect (either directly or indirectly) recent changes in precipitation and temperature in the region (Copland et al, 2011; Hewitt, 2007). Despite these recent advances in knowledge, the return periods of Karakoram glaciers are poorly constrained. An inventory of glacier surges presented by Copland et al (2011) identified several Karakoram glaciers that had surged more than once within the satellite era, and suggested their particular quiescent period may be 25–40 years, while historical accounts of thickening and thinning on the lower Khurdopin Glacier appear to follow an approximate 20-year cycle (Mason, 1930)
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