Interdecadal glacier inventories in the Karakoram since the 1990s
- 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
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).
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Fuming Xie et al.
Status: final response (author comments only)
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RC1: 'Comment on essd-2022-265', Anonymous Referee #1, 14 Oct 2022
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).
- AC2: 'Reply on RC1', F. Xie, 20 Jan 2023
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RC2: 'Comment on essd-2022-265', Rakesh Bhambri, 24 Dec 2022
Summary
This study presented a new glacier inventory for four time periods (1990, 2000, 2010, 2020) covering the Karakoram and surrounding region (upper Shyok basin) using Landsat satellite imagery and reported insignificant area loss in the study area. The manuscript is very well-written and nicely structured. I have given some minor suggestions for improvement. The important issue is an outline of the Karakoram region. The present study modified the extent of Karakoram (L131) presented by Bhambri et al. (2017) but did not mention the reasons for this change. Bhambri et al. (2022) recently reported no international standardization on the Karakoram extent. Therefore, consistency in the spatial extent of the Karakoram region is needed to quantify, analyze, and compare databases of natural and cultural resources for scientific investigation on a common platform and harmonization of scientific studies. Comparing glacier numbers and area statistics with previous studies is impractical (section 4.1) as all the studies on Karakoram glaciers have different area coverage. Bhambri et al. (2022) provided a most appropriate digital outline of the Karakoram region based on two decades (1920s and 1930s) long discussions and descriptive enumerations of the Royal Geographical Society (RGS) and the Survey of India (SoI). I suggest using this most common outline (open access) for the extent of the Karakoram and using the same outline to extract previous glacier inventory data on the same platform for comparison and modify section 4.1. If you do not want to use this outline, for the sake of harmonizing scientific studies, you can change the title to "Interdecadal glacier inventories in the Karakoram and the surrounding region since the 1990s".
Suggestions
L41-42 Uncertainty is the same ±3.68 in two sentences. If it is the same, write accordingly. You can write ±3.7.
L50 Present results in single-digit after the point (23.4 ± 28.8 km2). Please carefully check the entire manuscript. In some places, it is single-digit (e.g., L300), and in others in double-digit.
L59 Most glaciological studies usually avoid referring to countries' names for the Karakoram region. If you mention Pakistan in the first sentence of the introduction, then India and China must also be mentioned for the sake of neutrality. If you like, you can refer to the contested nature of this particular mountain region with different territorial claims between the different nation-states in a very general way. This is one aspect which creates continuous problems for ground truthing and field measurements. See Baghel and Nüsser (2015).
L89 "Moreover, the presented areas of glacier coverage differ partially substantially for the different available inventories (Bolch, 2019; Bolch et al., 2019)." Here you can mention Bhambri et al. (2022).
L91 "delineation with the exclusion of glacierized areas in glaciated areas steeper than 40°." Here two terms, ' glacierized' and 'glaciated', are used, and I could not understand them. Please see Cogley et al. (2010) for these terms.
L133 "The data were identified and processed using Google Earth Engine." For image processing or glacier mapping?
L153 for Karakoram boundary modified…. Please see my comment above.
L175 Bolch et al. (2010) used TM3/TM5 band ratio instead of NDSI. Therefore, Bolch et al. (2010) TM3/TM5 band ratio threshold must be different from NDSI.
L201 Please omit etc.
L218 Double space between can be
L223 Double space between developed processing
L293 This paper was published in 2006 (Granshaw and G. Fountain, 2017). Please check.
L394 between 0 "and" 50°
L414 "Karakoram boundary used by us is a little different from that in previous studies (Bolch et al., 2019; Bolch et al., 2012)," I don't think this is little difference. Also, please see my suggestions for the Karakoram boundary above.
L438 Scherler et al., (2018)
I hope this will help.
References
Baghel, R. and Nüsser, M., 2015. Securing the heights: The vertical dimension of the Siachen conflict between India and Pakistan in the Eastern Karakoram. Political Geography 48, pp. 24-36.
Bhambri R., Chand, P., Nüsser, M., Kawishwar, P., Kumar, A., Gupta, A.K., Verma, A., Tiwari, S.K., 2022. Reassessing the Karakoram Through Historical Archives - Environmental Change in South Asia: Essays in Honor of Mohammed Taher, in: Saikia, A., Thapa, P. (Eds.),. Springer International Publishing, Cham, pp. 139–169. https://doi.org/10.1007/978-3-030-47660-1_8
Bolch, T., Menounos, B. and Wheate, R., 2010. Landsat-based inventory of glaciers in western Canada, 1985–2005. Remote sensing of Environment, 114(1), pp.127-137.
Cogley, J.G., Arendt, A.A., Bauder, A., Braithwaite, R.J., Hock, R., Jansson, P., Kaser, G., Moller, M., Nicholson, L., Rasmussen, L.A. and Zemp, M., 2010. Glossary of glacier mass balance and related terms.
Granshaw, F.D. and Fountain, A.G., 2006. Glacier change (1958–1998) in the north Cascades national park complex, Washington, USA. Journal of Glaciology, 52(177), pp.251-256.
- AC1: 'Reply on RC2', F. Xie, 20 Jan 2023
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EC1: 'Moderate revisions', Niccolò Dematteis, 20 Jan 2023
Dear authors,
thank you for having submitted your responses to the reviewers' comments. I read your answers to the referees, which I appreciated, and I think that you can now proceed to upload your revised manuscript. It will be subject to a second round of revision by the referees.
Best regards
Niccolò Dematteis
Fuming Xie et al.
Model code and software
The multitemporal KGI data Xie et al., 2022 https://doi.org/10.12072/ncdc.glacier.db2386.2022
Fuming Xie et al.
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