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Long‐term monitoring of ice‐dammed lakes is important for understanding the process of lake storage, development, and glacial outburst flood (GLOF). Based on remote sensing observations for the period 1972–2020, we obtained what is so far the most detailed reconstruction of the filling and draining of Kyagar Lake, a typical annually ice‐dammed lake in the north Karakoram. We show that annually repeated lake fillings‐drainings were detected by satellite observations during two periods: 1996–2009 and 2015–2020, while between 2009 and 2015 no obvious cycle occurred. These two intermitted periods with regular annual revival of lake outburst were likely related to the long‐term cycle of glacier surge dynamics, namely two remarkable surge‐induced terminus accelerations during 1995–1997 and 2014–2016. Following each surge, the maximum lake areas decreased by about 33% from 1996 to 2009 and by about 88% from 2015 to 2020. Combined with climatic warming and the thinning of the ice‐dam, the storage capacity of Kyagar Lake will likely continue to decrease in the future, and the risk of lake outburst flood thus becomes lower. Repeated drainage following filling exacerbates the depletion of mass at the glacier terminal, leading to the cessation of storage and creating the conditions for the next glacial surge to occur, creating a long‐term iteration of the surge process. Considering the uncertainty and intensified climate changes, it suggests that a close monitoring of the glacial lake development and glacier dynamics would be still important. [ABSTRACT FROM AUTHOR]

Multi-temporal glacier inventories provide key information about the glaciers, their characteristics, and changes and are inevitable for glacier modelling and investigating geodetic mass changes. However, to date, no consistent multi-temporal glacier inventory for the whole of the Karakoram exists, negatively affecting the monitoring of spatio-temporal variations in glaciers' geometric parameters and their related applications. We used a semi-automatic method combining automatic segmentation and manual correction and produced a multi-temporal Karakoram glacier inventory (KGI) compiled from Landsat TM/ETM + /OLI (Thematic Mapper, Enhanced Thematic Mapper Plus, and Operational Land Imager) images for the 1990s, 2000s, 2010s, and 2020s. Our assessments using independent multiple digitisation of 37 glaciers show that the KGI is sufficiently accurate, with an overall uncertainty of ±3.68 %. We also performed uncertainty evaluation for the contiguous glacier polygons using a buffer of half a pixel, which resulted in an average mapping uncertainty of ±5.21 %. We calculated more than 20 attributes for each glacier, including coordinates, area, supraglacial debris area, date information, and topographic parameters derived from the ASTER GDEM (Advanced Spaceborne Thermal Emission and Reflection Radiometer global digital elevation model). According to KGI-2020s, approximately 10 500 alpine glaciers (>0.01 km 2 each) cover an area of 22510±828 km 2 of which 10.18±0.38 % (2290±84 km 2) is covered by supraglacial debris. Over the past 3 decades, the glaciers experienced a loss of clean ice and/or snow area but a gain in supraglacial debris. Supraglacial debris cover has increased by 17.63±1.44 % (343.30±27.95 km 2), while non-debris-covered glaciers decreased by 1.56±0.24 % (319.85±49.92 km 2). The total glacier area was relatively stable and showed only a slight insignificant increase of 23.45±28.85 km 2 (0.10±0.13 %). The glacier area has declined by 3.27±0.24 % in the eastern Karakoram, while the glacier area slightly increased in central (0.65±0.10 %) and western Karakoram (1.26±0.11 %). Supraglacial debris has increased over the whole of Karakoram, especially in areas above 4200 m a.s.l. (above sea level), showing an upward shift. The glacier area changes were characterised by strong spatial heterogeneity, influenced by surging and advancing glaciers. However, due to global warming, the glaciers are on average retreating. This is in particular true for small and debris-free glaciers. The multi-temporal KGI data are available at the National Cryosphere Desert Data Center of China: 10.12072/ncdc.glacier.db2386.2022 (F. Xie et al., 2022). [ABSTRACT FROM AUTHOR]

• Glaciers in the UIBKK experienced a slight negative mass budget from 2000 to 2019. • Mass balances in the UIBKK shifted from negative to positive from West to East. • An accelerated mass loss was found in the West UIBKK from 2000–2013 to 2013–2019. • Mass budgets in the East UIBKK shifted from negative to positive from 2000 to 2019. • Climate warming may play more important role in glacier changes in the study area. Water supply contributed by glacier and snow melt is of particular significance and play a key role for social stability in the Karakoram region of Upper Indus Basin (UIBKK). Based on the SRTM DEM, TerraSAR-X/TanDEM-X images and ZY3-02 stereo images, the spatiotemporal pattern of glacier mass budgets in the UIBKK have been estimated for the early 21st century (2000–2019) period in this study. A comparison of the total area in 2000 with that in 2019 shows that glacier area remained stable in the early 21st century, with a slight expansion of 56.3 km2 (0.4%). Glaciers in the UIBKK experienced a balanced or slight negative mass budget of −0.08 ± 0.07 m w.e. a−1 in the early 21st century. The spatial variability of mass budget in the UIBKK showed that glacier mass budgets shifted from negative to positive from West to East, respectively, along longitude. Glacier mass loss decelerated from −0.12 ± 0.16 m w.e. a−1 in 2000–2013 to −0.03 ± 0.21 m w.e. a−1 in 2013–2019. No significant differences were observed in thinning rates on debris-covered glaciers (≥19% area covered by debris) and clean-ice glaciers (<19% area covered by debris) in the early 21st century (−0.06 m a−1 vs −0.04 m a−1). The overall homogeneous mass budgets for surge and non-surge glaciers indicated that glacier surges seem not have a notable impact on glacier-wide mass budget over short time scales. The spatiotemporal variability of glacier mass budgets in the UIBKK are consistent with the tendencies of winter precipitation and summer temperature. Climate warming may play more important role in glacier changes in the UIBKK. [ABSTRACT FROM AUTHOR]