Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau
- 1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, People’s Republic of China
- 2College of Hydrology and Water Resources, Hohai University, Nanjing 210098, People’s Republic of China
- 3British Antarctic Survey, Cambridge, CB3 0ET, UK
- 4State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
- 1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, People’s Republic of China
- 2College of Hydrology and Water Resources, Hohai University, Nanjing 210098, People’s Republic of China
- 3British Antarctic Survey, Cambridge, CB3 0ET, UK
- 4State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China
Abstract. Glacier retreat is altering the water regime of the Tibetan Plateau (TP) as the region’s climate changes, but there remain substantial gaps in our knowledge of recent glacier loss in this region due to the difficulty of making- direct high-mountain observations and this limits our ability to predict the future of this important water resource. Here, we assessed 44 years of glacier area and volume changes in the major West Nyainqentanglha Range (WNT) that supplies meltwater to the densely populated Lhasa River basin and Nam Co, the second largest endorheic lake on the TP. Between the two periods 1976–2000 and 2000–2020, we found that the glacier areal retreat rate was more than doubled (from -0.54 ± 0.21 % a-1 to -1.17 ± 0.30 % a-1) and surface lowering also accelerated ( from -0.26 ± 0.09 m w.e.a-1 to -0.37 ± 0.15 m w.e.a-1) with particularly intense melting after 2014. This acceleration is similar in both timing and magnitude to that observed for Himalayas glaciers farther south. Besides, the areal retreat rate and mass loss rate of most glaciers in WNT were not synchronized. To understand the sensitivity of WNT glaciers to climate forcing, we examined the effects of topography, debris-cover, and the presence of proglacial lakes on our observed changes. We found consistently faster areal retreat but slower thinning rates on steeper slopes and an inconsistent relationship with aspect. We concluded that our observed spatial and temporal patterns of glacier change were dominated by observed local variations temperature and precipitation, the melt-reducing role of supraglacial debris, and the increasing influence of ice-marginal lakes on glacier retreat.
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Shuhong Wang et al.
Status: final response (author comments only)
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RC1: 'Comment on hess-2022-179', Anonymous Referee #1, 30 Jun 2022
The manuscript quantified changes in glacier area, surface elevation and mass balance in the WNT over the past 44 years and investigated associated influence factors over 1976-2000 and 2000-2020, based on multi-source remote sensing datasets. It is important to well understand the importance of glacier changes and associated impacts in the WNT, where these glaciers plays a critical role in regulating regional water resources through supplying meltwater to the densely populated Lhasa River basin and Nam Co. Overall, the science of the manuscript is very interesting, and the structure and writing of the manuscript are good, but there are some issues the authors should be considered.
- The key purpose of this study is to provide an internally consisitent dataset of glacier area and mass change in the WNT over the past 44 years. What is your purpose for obtaining this dataset? It should be the hydrological impacts of glacier changes in the basin. However, there is no discussion on hydrological impacts of glacier changes on water resources of the basin or Nam Co, so the authors can consider some discussion about the influence of glacier change on hydorology inthe WNT. It is very important for the manuscript, also for HESS.
- Glacier outlines: Chinese Glacier Inventory (CGI) I and CGI II are avalualbe now. The authors generated new glacier boundaries of this region in the years of 1976, 2000, 2014 and 2020 from Landsat images obtained from various years. How about the differences between your results and previous datasets? What is the main reason why generate a new dataset? The authors may add some discussion or analysis in the manuscript or supplementary matierial.
- Meterological data: Please give the elevations of these meterological stations used in the manuscript.
- As shown in Table 3, the area of debris cover and lake terminating decreases between two periods, but thinning increases. Why? In particular, some current studies confirmed that the spatial expansion and thickening of the debris layer have been observed on different debris-covered glaciers with glacier shrinkage and sustained mass loss (e.g., Stokes et al., 2007; Kirkbride and Deline, 2013; Tielidze et al., 2020; Xie et al., 2020). Just as a matter of interest, what is the reason leading to the reduction of debris cover on glaciers of this region? In addtion, between two periods, glacier number increases from 617 and 692 with an area decreasing. What happened?
- The manuscript analyzed glacier area change and surface elevation change for the periods 1976-2000 and 2000-2020, how about the total changes in glacier area and surface elevation change between 1976-2020? The authors may add two figures in the manuscript or supplementary matierial that show changes between 1976-2020.
- Minor comments:
1) Figure 1: Debris-cover is debris cover, Debris-cover glaciers is Debris-covered glaciers, and other glaciers is right?
2) Some units should be superscirpt.
3) Some References cited in the manuscript are missing in the Reference list. Please carefully check.
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AC1: 'Reply on RC1', Jintao Liu, 23 Aug 2022
Dear Reviewer,
Many thanks for your valuable comments on our manuscript (#hess-26-3901-2022) titled “Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau.” We have carefully addressed your concerns and suggestions. The quality of this manuscript has been enhanced.
In the attached Response to RC1, we provide point-by-point response to each reviewer comments (blue colored texts are our responses, while black texts are original comments).
Once again, we appreciate the time the reviewers put in reading our manuscript, and the comments were valuable, refreshing, and encouraging. My co-authors and I hope that we have adequately addressed all the review comments.
Sincerely Yours,
Jintao Liu, Shuhong Wang & Hamish D. Pritchard
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RC2: 'Comment on hess-2022-179', Anonymous Referee #1, 05 Sep 2022
The revised manuscript of “Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau” investigated changes in glacier area, surface elevation and mass balance and associated influence factors in the WNT over the past 44 years based on multi-source datasets. The authors have addressed most of reviewer’s comments and suggestions and have added other materials to the revised manuscript and supplementary material. In particular, they evaluate the hydrological impacts of glacier changes on water resources downstream through investigating the contribution of glacier meltwater to runoff variation of the Lhasa River station for the period of 1976-2013 and the Yangbajain station during 1979-2013. Compared to previous version, the new manuscript becomes better and can be accepted for publication of this journal.
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AC2: 'Reply on RC2', Jintao Liu, 05 Sep 2022
Dear Reviewer,
We appreciate your positive comments and valuable suggestions on our manuscript (#hess-26-3901-2022) titled “Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau.”
Best wishes!
Sincerely Yours,
Jintao Liu, Shuhong Wang & Hamish D. Pritchard
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AC2: 'Reply on RC2', Jintao Liu, 05 Sep 2022
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CC1: 'Comment on hess-2022-179', Xiangying Li, 17 Oct 2022
- The language is poor and should be revised and polished by a native English speaker at least.
- Some terminology or expression should be corrected throughout the full text. For example, some should be glacial melt, glacial terminal, proglacial lake, changes in glacial area ...,
- For the discussion on an increase in glacier populations as well as the response of authors “The reason for the increased glacier number but decreased area is that intact glaciers break down into several smaller glaciers in the process of glacier ablation”. This is fully wrong and should be corrected throughout the full text because a glacier can change to 2 branches rather than 2 glaciers.
- Figure 1 is not clear and the classification for legend and glaciers is not easy to understand for readers. For example, in situ glaciers, others glaciers, .... In addition, some figures should be removed or merged into one figure.
- I agree to the comments from RC1 “the authors can consider some discussion about the influence of glacier change on hydorology.... It is very important for the manuscript, also for HESS”. This is extremely necessary for this study and should be a key point in the conclusions.
- Relevant methods on glacier change can refer to published literature by some scholars. A lot of work has been done by Chinese scholars focusing on debris-covered glaciers (Haidong Han, et al.), proglacial lakes (Qiao Liu, Xin Wang, et al.), and changes in glacial area, elevation, mass balance, ... (Donghui Shangguan, Wanqin Guo, Shiyin Liu, et al.).
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AC3: 'Reply on CC1', Jintao Liu, 01 Nov 2022
Dear Xiangying Li
We thank you very much for the comments on our manuscript (#hess-26-3901-2022) titled “Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau.” We have carefully addressed your concerns and suggestions.
In the attached Response to CC1, we provide point-by-point response to each your comment (blue colored texts are our responses, while black texts are original comments).
Once again, we really appreciate the time you put in reading our manuscript. Hope we have adequately addressed all your comments.
Sincerely Yours,
Jintao Liu, Shuhong Wang & Hamish D. Pritchard
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CC2: 'Reply on AC3', Xiangying Li, 08 Nov 2022
The authors have well resolved my concerns, and I have no other questions.
- AC4: 'Reply on CC2', Jintao Liu, 08 Nov 2022
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CC2: 'Reply on AC3', Xiangying Li, 08 Nov 2022
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RC3: 'Comment on hess-2022-179', Anonymous Referee #2, 05 Dec 2022
This study assessed 44 years of glacier area and volume changes in the major West Nyainqentanglha Range (WNT) using comprehensive remote-sensed dataset. The seletect study area is a very typical and important glacial region on the TP, bounded by the Nam Co basin to the north and the Lhasa River basin to the south. In addition to the widely-studied climate factors, the effect of local modulators, such as debris cover, slope and aspect, on glacier thickness has also been investigated. Overall, this study is very interesting and would merit publication in HESS.My comments are as following:1. I am very interested in the impacts of elevation, slope, and aspect on the retreat rates and thinning rates. The elevation and slope may have correlations, so the contribution of each factor deserves further investitaion. For example, one can do the partial correlation analysis or analyze the impact of slope in each elevation band.Line 401: The following findings are interesting, and reasons need to be explained: "the retreat rate increased with slope while the thinning rate decreased."2. Figure 1: the extent of the study area should be marked in the map of TP (the upper left small figure).3. Figure 5 is not easy to read. The legend of elevation changes and the boundaries of glaciers need to be adjusted.4. It is difficult for me to understand the following sentences:Line 309: "our results agree within the uncertainties over the whole WNT, and the southeast WNT respectively"Line 323: "suggesting that the more strongly negative average for the longer 2000 to 2020 period (-0.37±0.12 m w.e. a−1) is the result of particularly strong negative mass balance after 2014"5. Some grammer and typo errors should be corrected, such as:Line 101: WNT range mountain rangeLine 311: our result. 4.1.2 Glacier mass balance.Line 364 and 367: I cannot find Figure 3c and Figure 3d
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AC5: 'Reply on RC3', Jintao Liu, 19 Dec 2022
Dear Reviewer,
Many thanks for your valuable comments on our manuscript (#hess-26-3901-2022) titled “Characterizing four decades of accelerated glacial mass loss in the West Nyainqentanglha Range of the Tibetan Plateau.” We have carefully addressed your concerns and suggestions. The quality of this manuscript has been enhanced.
In the attached Response to RC3, we provide point-by-point response to each reviewer comments (blue colored texts are our responses, while black texts are original comments).
Once again, we appreciate the time the reviewers put in reading our manuscript, and the comments were valuable, refreshing, and encouraging. My co-authors and I hope that we have adequately addressed all the review comments.
Sincerely Yours,
Jintao Liu, Shuhong Wang & Hamish D. Pritchard
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AC5: 'Reply on RC3', Jintao Liu, 19 Dec 2022
Shuhong Wang et al.
Shuhong Wang et al.
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