Multi-temporal elevation changes of Fedchenko Glacier, Tajikistan, from 1928 to 2021

Abstract The Fedchenko Glacier in central Pamir is one of Asia’s longest glaciers and has been a focal point for scientific investigation spanning the 20th and 21st centuries. This study explores a time series of elevation changes from 1928 to 2021 using diverse data sources: historical maps, optical digital elevation models from various sensors (KH-9, SPOT5 and Pléiades), ICESat laser altimetry and GNSS surveys. The mean rate of elevation change along the glacier center line over this period of 93 years is $-0.46\ \mathrm{m\ yr}^{-1}$ . The different sub-periods of elevation changes are investigated together with Fedchenko meteorological station data (1936–91) and ERA5 reanalysis (1950–2021). The most moderate thinning is observed during the earliest and coldest period (1928–58). The 1958–80 period is characterized by large thinning rates that can be partially explained by a dry anomaly and, locally, by a dynamic thinning related to a probable, but not directly observed, surge-like event. A wet anomaly in 1980–2010 potentially mitigated temperature-induced mass losses for this warm period, which is consistent with the observed moderate thinning. From 2010 to 2021, substantial thinning of $-0.31\,\mathrm{m\ yr}^{-1}$ was recorded in the accumulation area (>4800 m a.s.l.), in line with a broader trend of generalized mass losses in the Pamir region.