Dear authors

I read your response to the reviewers and the revised manuscript (MS). I do not think they meet yet the requirements to deserve a full re-review.

1/ The rebuttal letter should be more self-consistent. Currently it does not contain scientifically justified-responses to the referee comments and lacks some explanations. For example, reviewer 1 (Sam Herreid) made some detailed comments about the need to examine a consistent and meaningful spatial domain. Your response to this comment is simply to refer to new text and figures without any scientific explanations. Similarly, later in the rebuttal, you justify the use of a method (the buffer method) by citing three references from the co-authors of this study. This is not really convincing and you do not justify neither why you “excluded multiple digitization method in this version of manuscript”. This is not sufficient for a rebuttal letter that needs to convince the editor/reviewers that all concerns have been properly addressed.

2/ The manuscript is not ready neither. During a quick read, I found several typos, results reported with varying number of decimals, issues with section numbering etc… At this stage I expect an almost typo-free manuscript so that the reviewers can focus on the scientific content and how their concerns were addressed.

I have a lot of respect for the time spent by referees to evaluate and improve a paper. I will only send them a revised version if the MS and the rebuttal letter meet the quality level expected in TC.

I will carefully checked that you reply to all comments in an adequate way and that you provide an improved version of the paper before sending it to the referees.

Best regards,

Etienne Berthier

Dear authors

I now collected two reviews of your revised manuscript.

In general, reviewers are rather positive about your revision, acknowledge your efforts and agree that the manuscript has been improved compared to the initial submission.

However, both reviewers still made comments on several aspects of the study and ask for clarifications. At least one of them asked me to see the manuscript again, once carefully revised. As always, I also expect a clear response letter, explaining how each comment was addressed and taken into account in the re-revised manuscript.

Best regards,

Etienne Berthier

Dear Authors,

The two original reviewers were not in position to review the revised version of your article. I apology for the delay because I was aware of this only one week ago and I was in the field. So I did myself the review of your manuscript as soon as I could.

It is in general very much improved and could be accepted if the mostly minor revisions suggested below are carefully taken into account. I expect a point-by-point answer to my comments and how they were taken into account in the revised manuscript.

It is also time for all co-authors to help polishing the final version of the paper.

Do not hesitate to contact me if you have some further questions.

Best regards,

Etienne Berthier


I full agree with the change from a brief communication to a standard article.

Title: Adding the range of date of the study period would be useful to readers.

2.21. “nominal” is RGI jargon, but could you clarify this concept in full words for all readers.

2.23. “lower” than what?

2.30. Would be good to state what percentage of the overall Caucasus glaciers (in area) are found in the Greater Caucasus. To illustrate that you map debris for a large fraction of the Caucasus.

2.34. Why stating “At the same time, the terms northern and southern Greater Caucasus are commonly used.”? It complicates the picture and confused me a bit.

2.38. In the end we do not know in which of the three parts of Caucasus, Elbrus is located. Is Elbrus part of Greater Caucasus. Why is it treated separately?

2.40. (Tielidze and Wheate, 2018) should be moved just after “recent inventory”

3.9. Values of the temperature lapse rate should be negative. (temperature decrease while z increase)

3.11. Do they bring water to the back sea? Or do you want to say that evaporation from the back sea re-inforce the depression systems? Unclear.

3.21. Need to tell for what year.

3.27. I must say I am surprised that you need to quote a paper for the area of polygon. Not needed probably. Or if there is some understatement/complication hidden by this, make it clear.

Figure 1a. “percentage increase”. I think this is not the increase but just the percentage of debris cover. Double check.

6.5 Update the Mölg et al. Reference. Now publish. One of the co-author should be aware of that...

6.33. suggested change to “The number of debris-covered glaciers, i.e. with an areal percentage of debris larger than 10%,”

8.16. This is a bit confusing because the role of aspect as already been discussed. Make one paragraph to compare the different part of Greater Caucasus (east to west) and one paragraph for north/south differences.

8.23 “in the 3000-3500 m zone”

Figure 4. Clarify what are panels a, b and c. I suggest adding directly the time span on each panel to make the reading easier.

Figure 5. The figure gives hard work to the readers in part because the legend is not detailed enough. Is it only for Elbrus for all panels? (probably not but this is confusing). Are not % of SDC sufficient for panels b and C. The figure need to be re-thought.

Figure 6. Again a lot of information in this figure so that the reader feels a bit lost. Cannot you find a way to simplify it to really make your point?

11.3. superscript should be -1 not +1 here. Can the authors quote their result for this particular glacier (even if the period is slightly different)? Otherwise the reader cannot judge whether the two studies agree. And this is true for all comparisons to previous studies (by Popovnin, Lambrecht). Overall, the manuscript needs to be improved on this aspect.

11.17. For the glacier with outlines in RGI v6 (i.e. not nominal glaciers), it would be nice to have a 1 to 1 comparison of the % of debris cover from this study and Scherler et al. Do Scherler et al. overestimate the % of debris cover for all glaciers? What is the mean overestimation?, its standard deviation, etc...? A more thorough comparison with quantitative statistics would be welcome.

11.29. Can the authors quantify the mean up-glacier migration of the upper limit of the debris cover? It should be straightforward and it would be a useful numbers that future studies could quote and compare to.

11.33. Change “decreased by” to “changed by”. If you keep “decreased” then change sign from “-” to “+”

11.35-38. The Popovnin results were already compare to. They agree but do not “support” the interpretation. No need to repeat the agreement here.

12.1-4. Please be more specific in the text. Was there some rock avalanches on Suatisi and Devdoraki glaciers? Figure S5 indeed suggest so but it would be good to state it directly in the text with the date (or possible range of dates) of the rock avalanches.

13.13. “although smaller glaciers exist as well in high cirques”. Is it in the North? A bit ambiguous.

13.16. The sentence “But there are some exceptions, where the northern-facing glaciers are shorter and steeper, and here, the glaciers of the southern slope are characterized with relatively more supraglacial debris cover” is confusing again. I do not follow the reasoning.

13.9. The discussion is about increase in debris cover and here “rock glaciers” are mentioned. Again I do not follow the reasoning.

13.14. Because the lithology of the eastern and central Caucasus are described it should also be the case for the western Caucasus (and how it influences rock avalanches), otherwise the demonstration is not finished.

Maybe something to distinguish more clearly in the discussion is the two factors contributing to SDC increase in % (i) effect of glacier area loss and (ii) effect of increase in debris cover. Separating the two effects and how they evolve for each sub region would help organize the discussion.

13.37. The end of the sentence “as debris-covered glaciers may not be as sensitive to climate change as debris-free glaciers” is a general statement that has not much to do here and is vaguely connected to the rest of the sentence.

Figure 8. I must say that I find the figure quite confusing. Showing SDC only for the two dates would be best. I do not understand why the authors show clean ice if they do not really discuss it in the text.

Nicely written conclusion. However, I would not provide the name of specific instrument here (Kipp & Zonen or pulseEKKO. I do not thing this is the right place.

15.13. “Supraglacial debris-cover changes in the Greater Caucasus” should be replaced by “the supplement”

Dear Authors,

Thanks for taking into account my minor comments on the text.

I am delighted to accept your paper for publication in our journal. Thank you for choosing TC to publish your work.

I just listed a few typos that you would like to fix before uploading the files for production.

Do not hesitate to contact me if you have some further questions.

Best regards,

Etienne Berthier

Technical corrections/suggestions.
6.34. I would have used "smallest" but I am not 100% sure.
10.16. No comma after “Scherler”. Same issue in 11.2
11.18. "glacier retreat thinning" does not sound right. Thinning or retreat or both?
14.14. The Berthier et al. (2007) study is probably not the best reference for this fact and is somewhat outdated. It would be more appropriate to cite the Brun et al. 2019 study in this case.
Brun, F., Wagnon, P., Berthier, E., Jomelli, V., Maharjan, S. B., Shrestha, F. and Kraaijenbrink, P. D. A.: Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia, Journal of Geophysical Research: Earth Surface, 124(6), 1331–1345, doi:10.1029/2018JF004838, 2019.
14.35 "(percentage of debris cover larger than 10%)"
14.42. Remove "by"
15.16-24: put "S" before the number of the figures in this description of the supplement.