Land–Water–Energy Coupling System and Low-Carbon Policy Simulation: A Case Study of Nanjing, China
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIntro
"In 2018, multiple countries signed "Paris Agreement" to collaborate on greenhouse gas reductions [3]." Unfortunately, I regret to say that the Authors do not know the basic facts, including the date of the signing of the Paris Agreement, and they draw their knowledge of this momentous event and its findings only from the publication of Xu, Y.; Guo, N.; Ru, K. L.; Fan, S. L. Characteristics and optimization strategies of territorial space zone in Fujian Province, China based on carbon neutrality．Chinese Journal of Applied Ecology 2022, 33(02) : 500-508 (!)
Besides, I suggest considering the problem of CO2 emissions in the E7 group, where the 3rd emitter is currently the European Union, which has the ambition and chance to complete the transition at the earliest due to the most advanced implementation of energy and climate policies in the member states. References to these measures could be included in the discussion.
The article considers the problem of reducing CO2 emissions only from Nanjing City and China's perspective and experience, which it does not see as a negative aspect, but it could have been more emphasized and explained in the introduction in the context of policy-making and the results of their implementation.
2.2. Study area
"Following President Xi Jinping's proposal of dual carbon goals ..." I suggest some elaboration on this topic in the context of non-Chinese researchers
"The city plans to establish a "1+3+12+N" low-carbon development policy system, coordinating efforts to achieve carbon peak and carbon neutrality." I suggest detailing this information, as it is very interesting for non-Chinese researchers.
I suggest adding information about changes in population and urbanized areas in Nanjing from 2005 to 2021.
Fig. 2 Add a map with land use and river network, as the DEM model alone provides very limited information.
2.3. Data sources
I suggest adding a figure with maps of the 7 land use types in 2005 and 2021 or a summary table of changes in the area occupied by each land use type as this will provide an excellent background for understanding changes in CO2 emissions from land use. This will show the complexity of the phenomenon and embed considerations in space - this is also an important aspect when making recommendations.
2.4. System dynamics model "In this paper, the land use system was divided into seven land use types, which are cultivated land, garden land, forest land, grassland, land for settlements, industrial and mining, transportation land, and water area." 2.5.1. Carbon emissions from land use "In this study, the land use types in Nanjing City were divided into cultivated land, garden land, forest land, grassland and water area"
How many categories are analyzed - 7 or 5? Why was land for settlements, industrial and mining and transportation land excluded from the analysis of Carbon emissions from land use?
"the text following an equation need not be a new paragraph. Please punctuate equations as regular text." This passage probably should not be in the text. Rather, an explanation of the formula would be appropriate. The same comment applies to the last paragraph in 2.5.3. section.
3. Results
Table 5. 2011 - coal 8119526,726 - is this the right value?
4. Discussion
4.3.1. Increase investment in technological innovation to improve energy efficiency and expand the application scope of clean energy
The recommendation that the city should invest in the development of green energy could have resonated more strongly if the authors had stated what is the current (or better yet in the analyzed period) share of renewable energy in the energy balance of Nanjing. Then this recommendation is justified.
4.3.2. Reasonably plan land use structure
The recommendation to increase the area of forests is not justified, because we do not know how this affects the achievement of the goal of carbon neutrality.
4.3.3. Implement stricter water conservation policies
"to improve the standard of water consumption quota, clarify the red line of water consumption quota" What is this about?
In general, the recommendations in part do not follow from the results but are just a set of references to internal policies and facts known to the authors and are perhaps understandable to scientists from China, but from other countries not necessarily. I suggest that the recommendations should be based on the research conducted and not refer to issues that are not addressed in the text of the article.
Author Response
Point-by-point Responses to Reviewers
Responses to Reviewer 1:
Dear Respectable Reviewer, thank you very much for your kindness on reviewing our MS. I still have to thank you for providing us valuable suggestion on improving our MS during the process of reviewing. We have made a thoroughgoing revision of the MS. We have revised our MS based on your suggestion. As you may find the MS is better than before. Hopefully you will be satisfied with our revision and/or explanation can consider this work will be acceptable for Land. Great thanks!
- In 2018, multiple countries signed "Paris Agreement" to collaborate on greenhouse gas reductions [3]." Unfortunately, I regret to say that the Authors do not know the basic facts, including the date of the signing of the Paris Agreement, and they draw their knowledge of this momentous event and its findings only from the publication of Xu, Y.; Guo, N.; Ru, K. L.; Fan, S. L. Characteristics and optimization strategies of territorial space zone in Fujian Province, China based on carbon neutrality．Chinese Journal of Applied Ecology 2022, 33(02) : 500-508 (!)
Answer: Dear Respectable reviewer, thank you for valuable suggestion. I am very sorry that I did not have a complete and correct understanding of the basic facts of the Paris Agreement. Based on your suggestion, it has been modified in this section. Hopefully you will be satisfied with it. Great thanks.
- Besides, I suggest considering the problem of CO2 emissions in the E7 group, where the 3rd emitter is currently the European Union, which has the ambition and chance to complete the transition at the earliest due to the most advanced implementation of energy and climate policies in the member states. References to these measures could be included in the discussion.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Carbon emissions data from the European Union has been added in the “Introduction” section and a description of EU’s carbon reduction policies has been added in the “Discussion” section. Hopefully you will be satisfied with it. Great thanks.
3.The article considers the problem of reducing CO2 emissions only from Nanjing City and China's perspective and experience, which it does not see as a negative aspect, but it could have been more emphasized and explained in the introduction in the context of policy-making and the results of their implementation.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we have added the negative aspects of Nanjing's current policy formulation and implementation results, and added the policy making and experience of other countries and regions in the introduction section,. Hopefully you will be satisfied with it. Great thanks.
4."Following President Xi Jinping's proposal of dual carbon goals ..." I suggest some elaboration on this topic in the context of non-Chinese researchers
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, it has been added. Hopefully you will be satisfied with it. Great thanks.
- "The city plans to establish a "1+3+12+N" low-carbon development policy system, coordinating efforts to achieve carbon peak and carbon neutrality." I suggest detailing this information, as it is very interesting for non-Chinese researchers.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. That is a good question. It has been added. Hopefully you will be satisfied with it. Great thanks.
- I suggest adding information about changes in population and urbanized areas in Nanjing from 2005 to 2021.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, it has been added in the “Study area” section. Hopefully you will be satisfied with it. Great thanks.
- 7. 2 Add a map with land use and river network, as the DEM model alone provides very limited information.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, We added an extra map with land use and river network. Hopefully you will be satisfied with it. Great thanks.
- 8.I suggest adding a figure with maps of the 7 land use types in 2005 and 2021 or a summary table of changes in the area occupied by each land use type as this will provide an excellent background for understanding changes in CO2 emissions from land use. This will show the complexity of the phenomenon and embed considerations in space - this is also an important aspect when making recommendations.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, a figure with maps of the 7 land use types from 2005 to 2021 has been added in the “Data sources” section. Hopefully you will be satisfied with it. Great thanks.
- 9."In this paper, the land use system was divided into seven land use types, which are cultivated land, garden land, forest land, grassland, land for settlements, industrial and mining, transportation land, and water area." 2.5.1. Carbon emissions from land use "In this study, the land use types in Nanjing City were divided into cultivated land, garden land, forest land, grassland and water area"
How many categories are analyzed - 7 or 5? Why was land for settlements, industrial and mining and transportation land excluded from the analysis of Carbon emissions from land use?
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. I am very sorry for our carelessness when we prepare the MS. The correct categories are cultivated land, garden land, forest land, grassland, water area, land for settlements, industrial and mining and transportation land. It has been corrected and we added analysis of land for settlements, industrial and mining and transportation land in 2.5.1. Hopefully you will be satisfied with it. Great thanks.
- 10."the text following an equation need not be a new paragraph. Please punctuate equations as regular text." This passage probably should not be in the text. Rather, an explanation of the formula would be appropriate. The same comment applies to the last paragraph in 2.5.3. section.
Answer: Dear Respectable Reviewer, thank you for your valuable suggestion. I am very sorry for our mistake in editing the text. It has been deleted. Hopefully you will be satisfied with it. Great thanks.
- 11.Table 5. 2011 - coal 8119526,726 - is this the right value?
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. I am very sorry for the error we made in organizing the data. They have been corrected. Hopefully you will be satisfied with it. Great thanks.
- 12.The recommendation that the city should invest in the development of green energy could have resonated more strongly if the authors had stated what is the current (or better yet in the analyzed period) share of renewable energy in the energy balance of Nanjing. Then this recommendation is justified.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, the application status of clean energy and renewable energy in Nanjing has been added. We are sorry that we have tried our best, but there is no accurate proportion of renewable energy application in Nanjing at present, however, we still try our best to add relevant content to make our recommendation credible. Hopefully you will be satisfied with it. Great thanks.
- 13.The recommendation to increase the area of forests is not justified, because we do not know how this affects the achievement of the goal of carbon neutrality.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, it has been modified. Hopefully you will be satisfied with it. Great thanks.
- 14."to improve the standard of water consumption quota, clarify the red line of water consumption quota" What is this about?
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. The meaning of this sentence is to set the standard for saving water, but we are sorry that we did not express it properly. Based on your suggestion, we have modified this part. Hopefully you will be satisfied with it. Great thanks.
- 15.In general, the recommendations in part do not follow from the results but are just a set of references to internal policies and facts known to the authors and are perhaps understandable to scientists from China, but from other countries not necessarily. I suggest that the recommendations should be based on the research conducted and not refer to issues that are not addressed in the text of the article.
Answer: Dear Respectable reviewer, thank you for your valuable suggestion. Based on your suggestion, we have revised the recommendations in part to make it more closely related to the research results. Hopefully you will be satisfied with it. Great thanks!
Author Response File: 
Author Response.doc
Reviewer 2 Report
Comments and Suggestions for AuthorsDear authors,
Thank you for including me in the review of your paper titled “Land-water-energy coupling system and low-carbon policy simulation: A case study of Nanjing, China.” This paper analyses the interrelation between land use, energy, water systems, and carbon emissions from a systemic perspective. The aim of this study is to achieve carbon neutrality in 2060 at the natural development level. However, It seems illogical to predict changes that could happen over the next forty years, as they are difficult to quantify. Instead, why don't researchers work on shorter timelines, like ten years, to obtain more logical and acceptable results that can be implemented? Additionally, shorter timelines allow researchers to assess the impact of their predictions better, as the results are more accessible to track and measure. Furthermore, shorter timelines would force researchers to be more precise with their predictions, as there would be less time to wait for results.
This study should be revised to provide a better understanding of how the research findings can be applied at both the international and local levels in terms of policies and outcomes. Researchers should critically and analytically review policies and procedures, and strive to connect them to create a comprehensive framework that can be used. The current paper is limited to specific applications that only provide certain indications about a particular city. However, it does not draw from other studies to confirm the issue on a global scale.
A note worth reviewing: Climate changes consider only ten years, so how can we rely on data for the next 40 years? Data from the past 10 years can be used to make predictions about the future, but it will be necessary to review and adjust predictions over time to account for changing conditions. Additionally, it is important to consider the impact of climate change on different regions and populations.
Major revisions.
- “What is the full form of IPCC? (Page 1, line 29)”
- The theoretical framework of the study needs to be explained along with the diagram (Page 4, line 189).
- It is necessary to provide an explanation of the theoretical framework of the study accompanied by the figure that has been drawn.
- Was there a clear reason for choosing Nanjing City as the research subject?
- What are the original references to Jay W. Forrester and the History of System Dynamics, page 6, lines 226-233?
- Figures 3 and 4, titled "Cause and Effect of Urban Carbon Emission System" and "Stock and Flow Diagram of Urban Carbon Emission System," are difficult to understand.
- The researchers hold the equations, calculation methods, and conclusions, making it difficult to verify accuracy.
- The sentence, "The text following an equation need not be a new paragraph; please punctuate equations as regular text," is unclear.
- The discussion chapter requires a review of the references and text—for instance, paragraph page 15, lines 476-481, reference 2.
- It appears that several of the suggestions provided in the discussion section 4/3/1 are quite obvious and have no direct correlation with the findings of this study. Furthermore, the researchers have not evaluated these policies in the introduction or literature review sections, indicating that they are not closely linked to this study.
- It is important to ensure that policies focused on Nanjing are not presented in a way that suggests they cannot be implemented in other cities. To achieve this, researchers should carefully analyze the results and develop a framework that can be useful for other researchers and countries. This will enable policymakers to implement relevant policies in different regions and ensure that they are effective in achieving their intended goals.
Author Response
Point-by-point Responses to Reviewers
Responses to Reviewer 2:
Dear authors,
Thank you for including me in the review of your paper titled “Land-water-energy coupling system and low-carbon policy simulation: A case study of Nanjing, China.” This paper analyses the interrelation between land use, energy, water systems, and carbon emissions from a systemic perspective. The aim of this study is to achieve carbon neutrality in 2060 at the natural development level. However, It seems illogical to predict changes that could happen over the next forty years, as they are difficult to quantify. Instead, why don't researchers work on shorter timelines, like ten years, to obtain more logical and acceptable results that can be implemented? Additionally, shorter timelines allow researchers to assess the impact of their predictions better, as the results are more accessible to track and measure. Furthermore, shorter timelines would force researchers to be more precise with their predictions, as there would be less time to wait for results.
This study should be revised to provide a better understanding of how the research findings can be applied at both the international and local levels in terms of policies and outcomes. Researchers should critically and analytically review policies and procedures, and strive to connect them to create a comprehensive framework that can be used. The current paper is limited to specific applications that only provide certain indications about a particular city. However, it does not draw from other studies to confirm the issue on a global scale.
A note worth reviewing: Climate changes consider only ten years, so how can we rely on data for the next 40 years? Data from the past 10 years can be used to make predictions about the future, but it will be necessary to review and adjust predictions over time to account for changing conditions. Additionally, it is important to consider the impact of climate change on different regions and populations.
Dear Respectable reviewer, thank you very much for your kindness on reviewing our MS. I still have to thank you for providing us valuable suggestion on improving our MS during the process of reviewing. We have made a thoroughgoing revision of the MS.
Your suggestions are very accurate and a forecast time of 10 years would make the change more logical. However, based on the goal of achieving carbon neutrality by 2060, and taking into account the current policy direction, we ultimately set the study date for 2060. Based on your suggestions, we have carefully reviewed and examined our forecasting process to ensure that the results are always accurate. Furthermore, your suggestions have inspired us, and we will pay more attention to short-term prediction results in future studies, so as to provide more accurate policy guidance for the study of urban carbon emissions.
Based on your suggestions, we have revised the recommendations in the discussion section and designed a more complete integrated framework for better application of policies and outcomes at both the international and local levels.
Your suggestions are very valid and enlightening to us, we will review and adjust the results of our projections according to changing conditions in the future, and we will focus on the impact of climate change on different regions and populations in future studies.
We have revised our MS based on your suggestion. As you may find the MS is better than before. Hopefully you will be satisfied with our revision and/or explanation can consider this work will be acceptable for Land. Great thanks!
Major revisions:
- “What is the full form of IPCC? (Page 1, line 29)”
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, the full form of IPCC has been added. Hopefully you will be satisfied with it. Great thanks.
- The theoretical framework of the study needs to be explained along with the diagram (Page 4, line 189).
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, the explanation of the theoretical framework has been added. Hopefully you will be satisfied with it. Great thanks.
3.Was there a clear reason for choosing Nanjing City as the research subject?
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we have modified a clearer reason to explain why Nanjing is chosen as the research subject. Hopefully you will be satisfied with it. Great thanks.
4.What are the original references to Jay W. Forrester and the History of System Dynamics, page 6, lines 226-233?
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, the original references to Jay W. Forrester and the History of System Dynamics has been added. Hopefully you will be satisfied with it. Great thanks.
5.Figures 3 and 4, titled "Cause and Effect of Urban Carbon Emission System" and "Stock and Flow Diagram of Urban Carbon Emission System," are difficult to understand.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, they have been modified. Hopefully you will be satisfied with it. Great thanks.
6.The researchers hold the equations, calculation methods, and conclusions, making it difficult to verify accuracy.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we explained the source of data, the source of calculation method and formula, and added the history test of the model in the results part, so as to ensure the accuracy of our experiment. Hopefully you will be satisfied with it. Great thanks.
7.The sentence, "The text following an equation need not be a new paragraph; please punctuate equations as regular text," is unclear
Answer: Dear Respectable Reviewer, thank you for your valuable suggestion. I am very sorry for our mistake in editing the text. It has been deleted. Hopefully you will be satisfied with it. Great thanks.
8.The discussion chapter requires a review of the references and text—for instance, paragraph page 15, lines 476-481, reference 2.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we have carefully reviewed the references and text in the discussion chapter and modified it. Hopefully you will be satisfied with it. Great thanks.
9.It appears that several of the suggestions provided in the discussion section 4/3/1 are quite obvious and have no direct correlation with the findings of this study. Furthermore, the researchers have not evaluated these policies in the introduction or literature review sections, indicating that they are not closely linked to this study.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we have revised the recommendations in part to make it more closely related to the research results. Furthermore, the evaluation of policy has been added in the literature review sections. Hopefully you will be satisfied with it. Great thanks.
10.It is important to ensure that policies focused on Nanjing are not presented in a way that suggests they cannot be implemented in other cities. To achieve this, researchers should carefully analyze the results and develop a framework that can be useful for other researchers and countries. This will enable policymakers to implement relevant policies in different regions and ensure that they are effective in achieving their intended goals.
Answer: Dear Respectable reviewer, thank you for valuable suggestion. Based on your suggestion, we have revised the policy to make it as a useful framework for policymakers in other regions to implement the relevant policy. Hopefully you will be satisfied with it. Great thanks.
Author Response File: Author Response.doc
Reviewer 3 Report
Comments and Suggestions for AuthorsDear Authors,
The text develops an approach with relevance to the scientific community and presents a methodology that is not yet consistent in the bibliography of the subject. An analysis of the trend and logical relationship of urban carbon emissions is a process with high potential to help urban territories control their emissions and carbon sequestration process with the ultimate objective of carbon neutrality.
The communicated methodology appears credible and its replication by other researchers and in other geographical realities seems possible.
The bibliographical references appear appropriate to the treatment of the topic despite being unbalanced in their balance as they rely mostly on authors from the same region to deal with a global topic and on which there is very broad and extensive research already published.
Author Response
Point-by-point Responses to Reviewers
Responses to Reviewer 3:
Dear Authors,
The text develops an approach with relevance to the scientific community and presents a methodology that is not yet consistent in the bibliography of the subject. An analysis of the trend and logical relationship of urban carbon emissions is a process with high potential to help urban territories control their emissions and carbon sequestration process with the ultimate objective of carbon neutrality.
The communicated methodology appears credible and its replication by other researchers and in other geographical realities seems possible.
The bibliographical references appear appropriate to the treatment of the topic despite being unbalanced in their balance as they rely mostly on authors from the same region to deal with a global topic and on which there is very broad and extensive research already published.
Dear Respectable Reviewer, thank you very much for your kindness on reviewing our MS. I still have to thank you for providing us valuable suggestion on improving our MS during the process of reviewing. Based on your suggestions, we have carefully revised the reference section and added relevant research content from other countries and regions to make our research more credible. We have made a thoroughgoing revision of the MS. We have revised our MS based on your suggestion. As you may find the MS is better than before. Hopefully you will be satisfied with our revision and/or explanation can consider this work will be acceptable for Land. Great thanks!
Author Response File: Author Response.doc
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
Dear author,
After a thorough examination, the researchers considered all the notes.
Best regards
