Climate and Permafrost Shifts in Yakutia’s Arctic and Subarctic from 1965 to 2023

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper analyzes the climate and permafrost changes in the Yakutia's Arctic and subarctic regions over the past 50-60 years. The climate change model, freezing index, thawing index and other issues have been systematically studied. It is of great value to study the impact of global warming on permafrost, but there are some questions that need to be answered :

(1) What are the specific infrastructure risks in “The emergence of new conditions in landscape maintenance leads to permafrost degradation and infrastructure risks” mentioned in the introduction?

(2) What is the specific method to excluded data lacking significant correlations in “We excluded data lacking significant correlations, specifically for annual precipitation and snow cover thickness.”mentioned in the article?

(3) Similarly, the resolution of more pictures such as Fig. 2, Fig. 3 and so on is lower, and whether higher resolution pictures can be used.

(4) What is the basis for the distribution and selection of the 30 meteorological stations mentioned in the article ?

(5) The R² = 0.0384 of the fitted line in Fig.20, is the fitted line still meaningful ?

(6) The freezing index and thawing index mentioned in this paper are calculated by what method?

Author Response

Thank you very much for reviewing our manuscript. Your comments were valuable.

(1) What are the specific infrastructure risks in “The emergence of new conditions in landscape maintenance leads to permafrost degradation and infrastructure risks” mentioned in the introduction?

Global warming's impact on permafrost degradation can cause infrastructure risks  [13-17] (Shiklomanov et al., 2016; Streletskiy et al 2019, 2023; Hjort et al., 2018, 2022).

(2) What is the specific method to excluded data lacking significant correlations in “We excluded data lacking significant correlations, specifically for annual precipitation and snow cover thickness.”mentioned in the article?

We excluded data that did not have significant correlations, especially for annual precipitation. The assessment of precipitation characteristics of the New Siberian Island region did not include the data from weather station Sannikov Strait because of insufficient correlation between other station data.

We didn't consider snow cover thickness, so we removed it.

 

(3) Similarly, the resolution of more pictures such as Fig. 2, Fig. 3 and so on is lower, and whether higher resolution pictures can be used.

These Figures removed.

 

(4) What is the basis for the distribution and selection of the 30 meteorological stations mentioned in the article ? На чем основано распределение и выбор 30 метеорологических станций, упомянутых в статье?

We selected  24 meteorological stations. The selection was made using the most complete data for the years 1965-2023.

(5) The R² = 0.0384 of the fitted line in Fig.20, is the fitted line still meaningful?

Based on data from this weather station, the mean annual permafrost temperature at a depth of

1.6 m showed a insignificant trend of 0.01 °C/year from 1950 to 2009 (Figure 20).

(6) The freezing index and thawing index mentioned in this paper are calculated by what method?

Freezing-thawing index calculated based on the mean monthly air temperatures for a specific station (van Everdingen, 1998). Explanation include in Data and Methods.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper presents valuable data on climatic and permafrost characteristics changes in Arctic and Subarctic Yakutia. The results are interesting, but the manuscript requires its garmonisation. Below you will find my comments.

 

General comments:

Title: I suggest to remove the word “Analyzing” since the research paper is analysis itself.

Abstract: add more concrete results of the study, supporting them with quantity estimations.

The manuscript exceeds standard volume for the research paper standards (5,000-8,000 words). Thus, I recommend to relocate Tables 1-8 (which are quite bulky) into Appendix.

Figures 1 and 2: they should be omitted since they are not used in this study directly and are presented only as demonstration materials. You should put the reference on them in appropriate source.

Conclusion: the conclusion must show the readers what research gap was addressed instead of simple constatation of facts on air temperatures trends. For example, such results may be derived from any other plot of the Earth’s surface. The important is (for example) to show, how these changes affect permafrost and what evidences of permafrost landscapes changes did you reveal at this time.

Overall, the slight English correction of text is required.

 

Specific comments:

Line 57: do not start the sentence from the number.

Line 82: focused instead of focuses.

Line 128-129: please provide more concrete criteria of division of the climate-permafrost regions. It’s not clear from the presented text.

Line 132: I’d recommend to assign acronyms to the identified regions. For example, New Siberian Islands – NSI; Lena-Anabar – LA, etc. That would be more convenient to use acronyms instead of the full names in further analysis and descriptions.

Line 135: Just recommendation for the future studies: the climate changes in the Verkhoyansk-Chersky might be derived from the weather reanalysis data, which provides retrospective daily temperature data with spatial resolution of 0.25°.

Figure 3: make the labels’ font larger to make the labels more visible. Add inlet map of larger area for better understanding of location of study area by the international readers.

Lines 147-148: it’s unclear how did you identify the distinct boundaries. In recent publication (Yang et al., 2024; DOI: 10.1029/2023EF004309) the authors justified the boundaries of distinct changes in time series using Mann‐Kendall trend test. Thus, the justification of temporal boundaries is needed.

Line 175: what do you mean under “more intense cold” phrase?

Figure 9: in caption replace “thawing” with “freezing”

Line 281: 40 cm or 40 cm?

Table 4 – put dimensions in the precipitation values.

Line 416 – What is “long-term norm”? The air temperature always varies with certain magnitude and period, therefor the climate normal period is established as 30 years. Perhaps you mean anomalies in compare to particular period of time.

Line 424 – What do you mean under “depth of 30 m and a.s.l. of 49 m”?

Lines 421-425 – you indicate the borehole location as the foothills of the eastern slope of the Primorsky Ridge referring to Figure 16, while the Figure 16 caption sates that the borehole is located near Tiksi. Is there a mess? You’d better to put all mentioned in the manuscript boreholes on the map in Figure 1.

Lines 428-438 – this section must be transferred into Discussion section.

Lines 448-460 – these two sections must be transferred into Discussion section.

Lines 462-463: What do you mean when stating “The Olenek weather stations can be found in the Lena-Olenek subarctic area.”?

Figures 17, 18 and 19 might be merged into one graph.

Line 497: “sites” instead of “polygons”.

Line 502-503 – avoid mentioning “long-term norm”. These are anomalies from the average.

Lines 496-502 – the long-term monitoring data from CALM sites of the Arctic Yakutia were already analyzed in (Abramov et al., 2019/2021). If you are not focusing on deeper analysis of ALT variations, you’d better refer to that paper.

Line 512 – All this section (Cryogenic processes) must be transferred to Discussion section. The Results section must contain the authors’ data only.

Line 513 – the word “thawing” is missed in the end of sentence.

Figure 22 does not contain any justification on the activation of thermokarst process. There is no any temporal comparisons. Thus, this figure must be omitted since it does not bring any new data into the manuscript.

Line 536: worsened for whom? If you do not consider economic issues in the paper, you should avoid estimations “worsening”, “improving”, etc. The nature is not worsening itself.

Lines 539-544 – this section must be transferred into Introduction section since it does not discuss the data obtained and presented.

Lines 545-554 – How do these sentences related to the discussion of climatic and permafrost temperature trends? This part looks unbalanced.

Lines 555-559 – These statements must be confirmed with evidences from Results section or, at least, by the correspondent publication.

Line 588-594 – How do these sentences related to the discussion of climatic and permafrost temperature trends? You state on changes in vegetation and its affection on permafrost conditions, but you not provide any vegetation data in this paper.

Line 599 – you present the map of potential geocryological hazards, but you did not explain the methodology of its compiling and justification of the presented data. Similar work was recently done in Chukotka (Maslakov, A.; Zotova, L.; Komova, N.; Grishchenko, M.;   Zamolodchikov, D.; Zelensky, G. Vulnerability of the Permafrost Landscapes in the Eastern Chukotka Coastal Plains to Human Impact and Climate Change. Land 2021, 10, 445. https://doi.org/10.3390/land10050445). Thus, you should extend the section Methods and add the map compilation methodology.

Besides, you should state in the paper that your estimations are based on simple assumption that ice content of upper permafrost is one of the main factors affecting landscape susceptibility. High ice content of the deposits of the transient layer may serve as buffer and slowing down the active layer increasing. Oblogov et al. (2020) confidently proved that boggy landscapes of western Yamal with ice-rich upper permafrost almost did not experienced ALT increasing (and even decreasing) due to climate warming.

Lines 595-639 are actually belong to Results section. In the Discussion you should discuss the obtained results and compare them with the similar studies as you did that in the beginning of Discussion section. Besides, you do not discuss the climate change and permafrost temperature trends in the paper, which were presented in Results section in so details. Therefore, the paper looks as compilation of different parts by different people.

I recommend the manuscript for major revision and I do agree for repeated review.

Comments on the Quality of English Language

English correction of text is required.

Author Response

Thank you for your detailed review. We appreciate you.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Analyzing Climate and Permafrost Shifts Changes in Yakutia's Arctic and Subarctic over the past 50-60 Years

 

Alexander N. Fedorov, Pavel Y. Konstantinov , Nikolay F. Vasiliev , Stepan P. Varlamov , Yuri B. Skachkov , Alexey N. Gorokhov , Svetlana V. Kalinicheva , Rosalia N. Ivanova , Alexandra N. Petrova , Varvara V. Andreeva , Varvara A. Novopriezzhaya , Maxim A. Sivtsev , Mikhail N. Zheleznyak

 

COMMENTS

This paper is important to be published due to the presentation of a large amount of data and information on climatic and cryogenic regions affected by climatic variability in the Arctic and subarctic regions of Yakutia over the last 50-60 years. Direct and indirect observations are very valuable in a very little-known area for the international community of Geocryology.

The article provides a comprehensive analysis of climate and permafrost changes in Yakutia and highlights the potential hazards arising from these changes. The results of the study serve as a basis for further research about future impacts of climate change on permafrost, as well as for adapting human conditions in northern Yakutia to modern global warming. The authors distinguish interannual variabilities between cold (1965-1987) and modern warm periods (2005-2023) in the region.

On one hand the article examines how global warming affects permafrost, including rising permafrost temperatures, deepening of the active layer, and development of cryogenic processes. On the other hand, the authors analyze the importance of ice content in Yakutia permafrost affected by climatic variability. It is very known that the ice content in permafrost plays a crucial role as in the Yakutia region in vulnerability to negative cryogenic processes. It seems to be that the Yakutia ecosystems with permafrost and low ice content can adapt better to new climate conditions, while adaptation to an ecosystem with high ice content will be difficult for both nature and socioeconomic conditions.

The article includes the formation of other cryogenic forms of permafrost degradation as thermokarst, the thawing of ice wedges, vegetation changes and the development of other cryogenic processes. An interesting focus is on delineating the extent of current warming in specific regions and identifying the areas most vulnerable to cryogenic processes that adversely affect permafrost landscapes and human infrastructure. In this last point the article discusses the potential geocryological hazards associated with climatic variabilities in the Arctic and subarctic regions of Yakutia.

The text is very extensive in its analysis of temperatures, precipitation, and freezing and thawing indices, and their respective correlation coefficients. Considering that these values are reliable, there is a lack of discussion on this subject (for example when the values are not as expected). The manuscript includes some discussion of data but in the results, which should be included in the discussion if possible. DTL

Comments for author File: Comments.pdf

Author Response

Thank you very much for reviewing our manuscript. Your comments were valuable.

1. On one hand the article examines how global warming affects permafrost, including rising permafrost temperatures, deepening of the active layer, and development of cryogenic processes. On the other hand, the authors analyze the importance of ice content in Yakutia permafrost affected by climatic variability. It is very known that the ice content in permafrost plays a crucial role as in the Yakutia region in vulnerability to negative cryogenic processes. It seems to be that the Yakutia ecosystems with permafrost and low ice content can adapt better to new climate conditions, while adaptation to an ecosystem with high ice content will be difficult for both nature and socioeconomic conditions.

2. We removed this part of the work that connected with ice content and cryological risk. We' ll realized this one in different paper after.

We agree with you. We fixed it in the text.

3. Comment in the pdf-text.

Comments were corrected.

Reviewer 4 Report

Comments and Suggestions for Authors

This study presents a multidecadal analysis of climate variables, borehole temperatures, and vegetation type in the context of permafrost and its fate. There is a rich amount of information, however the organization needs improvement before this would be publishable. The story of the paper is unclear as are the key unique findings. Please see more detailed comments below. I feel the authors have compiled a great deal of very interesting data and information but their story needs to be better told before this is publishable.

 

Major comments

1) Figures 1, 3, and 25 are wonderful maps but they are not legible and the information from the maps needs to be recreated into a image that is appropriate for publication. It looks like the maps were scanned and then included in paper. There is a lot of wonderful information on the maps and it will require some thought on how to include it in a paper so that it is readable. The legends are missing and for Figure 1 the legend is in Russian, and would need to be in English for the journal readership.

2) The structure of the introduction is chaotic. There are many facts given but the story and the organization is not clear. The information is very interesting but how it ties together is unclear and more unclear is what this story is about. The abstract should include the concrete findings of the paper but currently there are only vague statements.

3) There is a very large amount of information and 25 figures. I think refining the story of the paper will help reduce the information and move some information to an appendix. Are all the tables necessary? What story are they telling? Some could be moved to a supplemental sections to serve as a reference for those who want such detail. The authors should consider splitting the paper into 2 if they can not remove materials.

4. Methods and data section is not well organized. The data and methods are all mixed and not clearly explained. I suggest two sub sections. Discuss data first, make a table of the weather stations, their lat/lon etc.., years of record etc, so this does not need to be in the text later. Include a paragraph about the borehole temperatures. Then add another sub section for methods and explain your epoch analysis (breaking into periods), correlation methods etc.. I noticed that methods were discussed later in the results sections, which was distracting. Provide details on borehole temperature (what is the vertical resolution?).

5. Line 126-135, this looks like a summary paragraph that seems more appropriate for the conclusions or discussion section.

6. Figure 3, is this defined in past work? Was it a conclusion on current analysis? THis was confusing.

7. line 190, thawing  & freezing index and all the other indices should be defined in the methods section.

8. Line 423, cite the reference in this sentence when this statement is made. Currently it is in the second sentence.

9. Fig 17 Caption. State what is shown and then note the trend line.

 

Minor comments

1. Line 63, This sentence confused me ' The climate and permafrost ... not examined independently'. Then all the text after this cites previous work that looked at meteorology and permafrost separately. Is this the main goal of the paper? If that is the case then you need to convince the audience why this is important to do. I felt that the paper was disjoint as meteorology was discussed and then borehole temperatures were discussed separately. IT seemed like two separate stories.

2. Lines 76-96 - past work need better structure. Currently it is a list of facts but not tied together.

3. Line 112, I do not understand what is being correlated.

Comments on the Quality of English Language

The english needs some polishing and is fine overall. It is the structure of the paper which is difficult to understand.

Author Response

1. Figures 1, 3, and 25 are wonderful maps but they are not legible and the information from the maps needs to be recreated into a image that is appropriate for publication. It looks like the maps were scanned and then included in paper. There is a lot of wonderful information on the maps and it will require some thought on how to include it in a paper so that it is readable. The legends are missing and for Figure 1 the legend is in Russian, and would need to be in English for the journal readership.

Fig.1, 2 and 25 have been removed. Fig.3 has been corrected.

2. The structure of the introduction is chaotic. There are many facts given but the story and the organization is not clear. The information is very interesting but how it ties together is unclear and more unclear is what this story is about. The abstract should include the concrete findings of the paper but currently there are only vague statements.

The entire text has been reviewed and corrected.

3. There is a very large amount of information and 25 figures. I think refining the story of the paper will help reduce the information and move some information to an appendix. Are all the tables necessary? What story are they telling? Some could be moved to a supplemental sections to serve as a reference for those who want such detail. The authors should consider splitting the paper into 2 if they can not remove materials.

Part of the article regarding cryogenic risks, ice content and exogenous processes was removed. We agree with you, it is difficult to combine two topics in one article.

4. Methods and data section is not well organized. The data and methods are all mixed and not clearly explained. I suggest two sub sections. Discuss data first, make a table of the weather stations, their lat/lon etc.., years of record etc, so this does not need to be in the text later. Include a paragraph about the borehole temperatures. Then add another sub section for methods and explain your epoch analysis (breaking into periods), correlation methods etc.. I noticed that methods were discussed later in the results sections, which was distracting. Provide details on borehole temperature (what is the vertical resolution?).

The Methods section has been revised taking into account your comments.

 

5. Line 126-135, this looks like a summary paragraph that seems more appropriate for the conclusions or discussion section.

We presented another version

6. Figure 3, is this defined in past work? Was it a conclusion on current analysis? THis was confusing. This is a new permafrost-climatic zoning based on the permafrost-landscape map (2018).

7.line 190, thawing  & freezing index and all the other indices should be defined in the methods section.

We agree with you. The definition is given in the Methods section.

 

8. Line 423, cite the reference in this sentence when this statement is made. Currently it is in the second sentence.

We didn't find where it is.

9. Fig 17 Caption. State what is shown and then note the trend line.

Corrected.

Minor comments

1. Line 63, This sentence confused me ' The climate and permafrost ... not examined independently'. Then all the text after this cites previous work that looked at meteorology and permafrost separately. Is this the main goal of the paper? If that is the case then you need to convince the audience why this is important to do. I felt that the paper was disjoint as meteorology was discussed and then borehole temperatures were discussed separately. IT seemed like two separate stories.

We have removed this offer. We corrected this throughout the text.

2. Lines 76-96 - past work need better structure. Currently it is a list of facts but not tied together.

We agree with you and have added clarifications in the text.

3. Line 112, I do not understand what is being correlated.

We removed it from the text.

4. The english needs some polishing and is fine overall. It is the structure of the paper which is difficult to understand.

We did English correction in LAND Office.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised almost all of my suggestions and corrections. Although some parts of the text remain unchanged despite of my comments, I respect the authors' vision of the study design and agree with their justified opinion.

The manuscript may be published after slight modification of the title: "past 50-60 years" must be replaced by the years period (1965-2023). In ten years the last 50-60 years will be the different years.

Author Response

1. The manuscript may be published after slight modification of the title: "past 50-60 years" must be replaced by the years period (1965-2023). In ten years the last 50-60 years will be the different years.

   Title was changed: Climate and Permafrost Shifts in Yakutia's Arctic and Subarctic from 1965 to 2023

2.  

Reviewer 4 Report

Comments and Suggestions for Authors

 

The paper is much improved, and I had minor suggests. My major comment is that the discussion needs revising. It is not easy to follow and the structure is confusing. I have suggestions below in major comment 3.

 

Major

1.        Are the lines in Fig 4-7 anomalies? Is the mean removed? It is not clear from caption or the methods section descriptions. This need to be clarified by specifying that what is shown has had the mean removed. I believe so but am not positive.

2.        Line 122: ‘Data without strong correlations… was removed’  It is unclear to me what the correlations represent. Is it with other stations in the group? That is what I think it is but am not sure that this is what it always means. It is clear on line 291-299 how correlations are used.  Please clarify in the methods section.

3.        Discussion: Please revise this for better structure and clarity. The first two paragraphs seem disconnected from the story, particularly the permafrost discussion. They provide facts but I suggest you weave them in later. The third paragraph seems a more appropriate way to start the Discussion. I see the key topics as: a) vegetation change as a result of climate change and permafrost change, b) permafrost and c) a view of these 3 periods. I suggest that you reorder your discussion A) climate change and the 3 periods, I suggest that you refer to the papers Bekryaev et al 2010 Journal of Climate 2010, ‘Role of Polar Amplification in Long-Term Surface Air Temperature Variations and Modern Arctic Warming.’ This paper puts your results of the three periods and the gradients you see in the larger climate variability context. B) Discuss the permafrost changes and consequence due to the climate, thermokarst and degradation of ice wedge polygons then C) vegetation and how it has been impacted. A revised discussion will strengthen the paper.

 

Minor

1.        Line 112-113: This sentence needs a noun. Change to ‘They usually use data…’

2.        Line 114: change to ‘In this paper…’

3.        Line 121: change to ‘correla-‘

4.        Line 128: change to ‘negative daily air temperatures in ˚C.’

5.        Line 129: change to ‘The freezing-thawing index’

6.        Line 131: change to ‘divid-‘

7.        Line 139-145: correct formatting, text in bold and section heading not numbered.

8.        Line 152: remove one extra ‘.’

9.        Line 178, figure 2 caption formatting needs to be fixed.

10.  Figure 2, purple text ‘-1,1’. Is the ‘,’ used as a decimal place? What is the standard format for this journal. I am more familiar with ‘ -1.1’ but am familiar with ‘-1,1’.

11.  Line 197: remove one extra ‘.’

12.   Line 533: meaning is not clear ‘on the periods of climate development.’

Author Response

Major

1. Are the lines in Fig 4-7 anomalies? Is the mean removed? It is not clear from caption or the methods section descriptions. This need to be clarified by specifying that what is shown has had the mean removed. I believe so but am not positive.

We believe that the term anomaly is not appropriate here. Fig. 4-7 and other figures show a deviation from the average value of the characteristics shown, i.e. from the value 0. An anomaly can cause negative processes, but we do not show them here.

2. Line 122: ‘Data without strong correlations… was removed’  It is unclear to me what the correlations represent. Is it with other stations in the group? That is what I think it is but am not sure that this is what it always means. It is clear on line 291-299 how correlations are used.  Please clarify in the methods section.

We realized our mistake. We corrected it for the correlation coefficient.

 

To l.122: Meteorological station selection in permafrost-climatic regions considered correlations links between station data. Data without strong correlation coefficient, especially for annual precipitation, was removed. The weather station at Sannikov Strait was omitted from the assessment of precipitation in the New Siberian Islands because its data did not show sufficient correlation coefficient with other stations.

 

Ll. 291-299: Precipitation. Weather stations in the Arctic zone of Yakutia, the New Siberian Islands, and the Anabar–Lena region have numerous gaps in precipitation measurements. As examples for these two regions, data from the Kotelny Island and Saskylakh weather sta-tions, which have continuous data since 1966, were used. The Tiksi weather station data were excluded from the Anabar–Olenek region due to the lack of significant correlation coefficient with the Saskylakh weather station data. The data in the Yana–Kolyma region exhibit significant correlations coefficient  (0.30 to 0.52 at p ˂ 0.05) with n = 47, except for one insignificant correlation coefficient between the Yubileinaya and Chokurdakh weath-er stations. The data from the Tiksi meteorological station show a correlation coefficient with the data from all three weather stations in the Yana–Kolyma tundra, ranging from 0.45 to 0.50.

3. Discussion: Please revise this for better structure and clarity. The first two paragraphs seem disconnected from the story, particularly the permafrost discussion. They provide facts but I suggest you weave them in later. The third paragraph seems a more appropriate way to start the Discussion. I see the key topics as: a) vegetation change as a result of climate change and permafrost change, b) permafrost and c) a view of these 3 periods. I suggest that you reorder your discussion A) climate change and the 3 periods, I suggest that you refer to the papers Bekryaev et al 2010 Journal of Climate 2010, ‘Role of Polar Amplification in Long-Term Surface Air Temperature Variations and Modern Arctic Warming.’ This paper puts your results of the three periods and the gradients you see in the larger climate variability context. B) Discuss the permafrost changes and consequence due to the climate, thermokarst and degradation of ice wedge polygons then C) vegetation and how it has been impacted. A revised discussion will strengthen the paper

The structure has been corrected as recommended.

Add one paragraph links with Bekryaev et al., 2010

Bekryaev et al., 2010, Journal of Climate 2010, ‘Role of Polar Amplification in Long-Term Surface Air Temperature Variations and Modern Arctic Warming.’ – adding in References.

 

Minor

1. Line 112-113: This sentence needs a noun. Change to ‘They usually use data…’

Changed.

2. Line 114: change to ‘In this paper…’

Changed.

3. Line 121: change to ‘correla-‘

Changed.

4. Line 128: change to ‘negative daily air temperatures in ˚C.’

Changed.

5. Line 129: change to ‘The freezing-thawing index’

Changed.

6. Line 131: change to ‘divid-‘

Changed.

7. Line 139-145: correct formatting, text in bold and section heading not numbered.

Changed.

8. Line 152: remove one extra ‘.’

Removed.

9. Line 178, figure 2 caption formatting needs to be fixed.
10. Figure 2, purple text ‘-1,1’. Is the ‘,’ used as a decimal place? What is the standard format for this journal. I am more familiar with ‘ -1.1’ but am familiar with ‘-1,1’.

Changed: style in ‘-1.1’ in Figures 2 and 8.

11. Line 197: remove one extra ‘.’

Removed.

12. Line 533: meaning is not clear ‘on the periods of climate development.’

Changed: ‘from the periods of climate development.’