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Abstract:
The study attempts to gain a better understanding of glacier dynamics of ~5600 glaciers covering ~17950Km2 in the Karakoram. Based on 20-year glacier area change (-0.96%) using Landsat data (2000-2020, it was shown that the glaciers are either retreating (3621), stable (1766), or even advancing (215), indicating an average recession of -4.64%, -.08% and 1.17% respectively with variation between east and west Karakoram. The analysis showed a significant influence of topography on the observed glacier changes indicated by higher altitudes and northerly aspects of the Advancing and Stable glaciers' and lower altitudes and southerly aspects of the Retreating glaciers. Due to data limitations, ice thickness changes of only a subset of the glaciers (375) were estimated using ICESat-2 altimetry (2021–2022) and SRTM DEM (2000) data. With an average thinning of -0.12 ± 0.33 ma-1, there is less thinning in the western Karakoram (-0.09 ma-1) than the eastern Karakoram (-0.16 ma-1). The thickness of the advancing glaciers increased somewhat (0.06 ma-1), the stable glaciers decreased little (-0.03 ma-1) and the retreating glaciers decreased significantly (-0.32 ma-1). The GlabTop model, based on SRTM and TanDEMx DEMs, glacier outlines and flowlines of 375 glaciers, was used to predict volume changes during 2000-2012. The model showed an overall loss of 27.0±8.9 Gt with the Advancing, Stable and Retreating glaciers losing -1.65±0.54Gt, -19.28±6.36Gt and -6.08±2.0Gt of mass respectively. Furthermore, despite advance many of the Advancing glaciers showed significant thinning (-0.7 ma-1) and considerable mass loss during 2000-2012 indicating an anomaly which is under further investigation.
