1Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming 650500, China
2Institute of International Rivers and Eco-security, Yunnan University, Kunming, Yunnan 650500, China
3State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
4School of Geography and Sustainable Development, University of St Andrews, St Andrews KY19 9AL, Scotland, United Kingdom
5Department of Geosciences, University of Oslo, Oslo, 0316, Norway
6Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
7National Cryosphere Desert Data Center, Lanzhou 730000, China
8College of Geography and Environmental Sciences, Northwest Normal University, Lanzhou 730070, China
9Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
10School of Resource Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan, China
11Department of Agricultural Engineering, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan
1Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming 650500, China
2Institute of International Rivers and Eco-security, Yunnan University, Kunming, Yunnan 650500, China
3State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
4School of Geography and Sustainable Development, University of St Andrews, St Andrews KY19 9AL, Scotland, United Kingdom
5Department of Geosciences, University of Oslo, Oslo, 0316, Norway
6Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
7National Cryosphere Desert Data Center, Lanzhou 730000, China
8College of Geography and Environmental Sciences, Northwest Normal University, Lanzhou 730070, China
9Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
10School of Resource Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan, China
11Department of Agricultural Engineering, Muhammad Nawaz Shareef University of Agriculture, Multan, Pakistan
Received: 02 Aug 2022 – Discussion started: 11 Oct 2022
Abstract. 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-tempo glacier inventory for the whole of the Karakoram exists, negatively affecting the monitoring of spatiotemporal variations of glaciers’ geometric parameters and their related applications. We used a semi-automatic method combining automatic segmentation and manual correction and produced multi-temporal Karakoram glacier inventories (KGI) compiled from Landsat TM/ETM+/OLI images for the 1990s, 2000s, 2010s, and 2020s. Our assessments using independent multiple digitization 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 ±3.68 %. 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. According to the KGI-2020, approximately 10500 alpine glaciers (> 0.01 km2 each) cover an area of 22510 ± 828 km2 of which 10.18 ± 0.38 % (2290 ± 84 km2) are covered by supraglacial debris. Over the past three decades, the glaciers experienced a loss of clean ice/snow area but a gain in supraglacial debris. Supraglacial debris cover has increased by 17.63 ± 1.44 % (343.30 ± 27.95 km2) while non-debris-covered glaciers decreased by 1.56 ± 0.0.24 % (319.85 ± 49.92 km2). The total glacier area was relatively stable and showed only a slight insignificant increase of 23.45 ± 28.85 km2 (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 whole Karakoram, especially in areas above 4200 m a.s.l., showing an upward shift. The glacier area changes were characterized 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: https://doi.org/10.12072/ncdc.glacier.db2386.2022 (Xie et al., 2022a).
The manuscript deals with the compilation of a glacier inventory in the Karakoram region. The topic is of high interest to the scientific community, and not only.
The manuscript is well written (there are a few typos to check, e.g. line 248), but there are some issues to be solved before its publication. First of all, authors need to describe all the, employed, data at the beginning of Section2; currently, ancillary data, which constitute an important part of the processed ones, are progressively introduced during the description of the various elaboration.
Concerning subsection 2.6, to improve readers' comprehension, a figure, like Fig. 4, should be added. Moreover, if applied to debris-covered glaciers, the discrepancies between the two methods highlight their proneness to errors in their mapping.
In Section 4, the authors should immediately state that due to the different approaches, data sources and methods cannot be compared without a high level of uncertainty and maybe, only qualitatively. Subsection 4.3 should be shortened and merged with the previous one.
Conclusions should mention that the processing is carried out by semiautomatically processing Landsat images and ancillary data.
Additionally, some parts need rephrasing as they are unclear to the reader:
Lines 174-181;
Lines 292-307.
In the data repository, the uncertainty statement is different from the one cited in the paper [±5.03% ≠ ±3.68%], please clarify.
There are also minor comments as follows:
Subsection 2.5 is written in the wrong format;
Line 485, please mention rockfalls in addition to avalanches;
when regression or correlation analyses are cited statistical significance (p value) and the correct parameter should be cited;
Maps should be improved by removing the north arrow and scale (the coordinates in the outline give the same information) or by placing them in the same area of the legend (i.e. unique white background).
In this study, first we generated inventories which allowed us to systematically detect glacier change patterns in the Karakoram range. We found that, by the 2020s, there were approximately 10 500 glaciers in the Karakoram mountains, covering an area of 22 510.73 square kilometers of which ~10.2 % is covered by debris. During the past 30 years, the total glacier cover area in Karakoram remained relatively stable from 1990 to 2020, with a slight increase in area of 23.5 square kilometers.
In this study, first we generated inventories which allowed us to systematically detect glacier...
