Review Reports - Domestic Regional Synergy in Achieving National Climate Goals—The Role of Comparative Advantage in Emission Reduction

Round 1

Reviewer 1 Report

Review of “Domestic Regional Synergy in Achieving National Climate Goals - The Role of Comparative Advantage in Emission Reduction” by Chen et al. for Land. The authors have developed and used a game-theory-based model to analyze emission reduction undertaken with various levels of regional cooperation. The paper is well-written, methodologically sound, and addresses an interesting and important issue. It has the potential to make a significant contribution to the academic community.

Minor Comments

Do the authors mean a game theory-based model in line 11?

A citation for the sentence starting in line 210, “According to the Environmental Kuznets Curve”, should be added.

A small typo/lack of space is in line 316 in “25 climate cooperation”.

In the conclusion section, the authors make the point that for regional synergetic emission reduction to work, it has to meet the twin goals of emission reduction and maintaining economic growth. They provide a conceptual validation of the proposed model in section 4.1 by discussing the case study of the collaborative management of air pollution in Beijing, Tianjin, and Hebei. In the last paragraph of section 4.2, they provide some ways the model could be improved without discussing model limitations. One model limitation is the need to incorporate socio-political factors, which could make regional synergetic emission reduction difficult or slow down the process. The authors could postulate in 1-2 how to incorporate this societal persistence to change, given that regional synergetic emission reduction is bound to lead to some winners and losers in both regions. This could also open a discussion into how all players could be incentivized to cooperate. Such a discussion would be helpful to readers, esp policy-makers.

Author Response

Dear Reviewer:

On behalf of my co-authors, we thank you for giving us a chance to revise and improve the quality of our manuscript. We greatly appreciate your comments, as they provided us with new perspectives for revising and polishing the manuscript. We have tried our best to make appropriate revisions according to these comments and suggestions and have marked revisions with red font in the paper. We would like to respond to each of your comments as follows:

Response to comment 1: Thank you for the correction. The use of "game theory-based model" is more standard and rigorous here, and we have modified it in the manuscript.

Response to comment 2: We have added new citations to the manuscript: Dinda, S. Environmental Kuznets Curve Hypothesis: A Survey. Ecol Econ 2004, 49(4), 431-455. DOI:10.1016/j.ecolecon.2004.02.011.

Response to comment 3: We have fixed the error there and checked for formatting errors elsewhere in the text.

Response to comment 4: Your point is very instructive to us about the importance of socio-political factors in climate change cooperation, especially given that climate change mitigation requires the establishment of durable and stable regional cooperation. This is something that the static model in this paper cannot explain further. Therefore, we explain the limitations of the model and suggest issues that can be further developed in the future to address this limitation. On the one hand, our model is based on short-term static analyses and is unable to analyse the long-term dynamic problem of stable cooperation. Future research can extend our study with dynamic game and dynamic general equilibrium models. On the other hand, our model does not focus on socio-political factors and constructs a utility function using only eco-nomic gains and climate change damages. It's undeniable that socio-political factors are very important in climate change cooperation, and issues such as public attitudes to-wards climate change and environmental issues, mechanisms for the promotion of officials, and the right to development in the region all influence the formation of cooperation. These factors could be used to enrich our model in future research.

Reviewer 2 Report

In the article, the authors raised important issues related to climate change, the impact of emissions and the relationship with economic development. The layout of the article is understandable and logical. The authors correctly described the individual chapters of the article.

However, there are some inconsistencies in the content:

1. In the abstract, the authors should write about the emission of which gases are they talking about? Climate change is caused by the emission of gases, there are many of them, it should be emphasized at the outset what gases are we talking about?

2. The figures would be clearer if there was a description below them of what all the contained symbols mean, what the solid and dashed lines mean, etc.

3. The authors used an interesting research method, and in the part with the results there are many interesting descriptions and conclusions. However, these parts do not reflect the essence of the article in the summary. The second and third paragraphs mainly present the results of the study, but they are obvious, it is known without such sophisticated analyzes and research methods. It is worth summarizing the results of the study in a more interesting way.

Author Response

Dear reviewer:

Response to comment 1: Thank you for pointing out that our writing in this section was not rigorous and that the lack of a definition of the emitting gas could indeed be misleading to the reader. In response to your suggestion, we have specified CO₂ emissions in the introductory section of the manuscript. In the process of achieving climate change goals, it is common to focus on CO₂ or greenhouse gas emissions, of which CO₂ is the main research issue for the current warming goals, so this paper focuses on CO₂ emissions.

Response to comment 2: Because each figure involves multiple subfigures and the symbols associated with each subfigure have different meanings, labelling under the figures may be somewhat difficult or seem lengthy. In the paragraphs above each figure, we have described the meaning of the symbols, solid and dotted lines in each figure separately.

Response to comment 3: We have taken your comments on board and revised the abstract. The original abstract seemed very long and we used a lot of space to present the results of our study instead of highlighting the highlights of our study. After the revision, the abstract now provides a short summary of our main findings, reflecting the main innovations of the study in a more intuitive way.

Reviewer 3 Report

The research is interesting and it concerns a contemporary and important issue. The paper is well structured and it has some interesting findings (some of which were anticipated). Its aim is to prove that cooperation is effective, in the sense that it can contribute to both emission reduction goals and economic benefit, without explaining/proposing how this can be done, given the difficulty of regional synergy (as the authors also mention). Of course, as the authors themselves point out that the article aims to create a model to be used for future analyses.

The introduction is well structured and comprehensive.

I agree with the authors that cooperation between regions is important, but it has to be done on some terms. For example, based on sub-sections 3.2.3 and 3.2.5, it is more efficient for a region to purchases carbon-intensive goods from other regions (with, relatively lax emissions regulations) but this has an environmental cost for the later.

In sub-section 4.1 you state that “China has set the goal of "carbon peaking and carbon neutrality" to mitigate climate change” (lines 600-601), this is based on a Law? Maybe you could have a reference here.

In sub-section 4.1 you mention the “Beijing-Tianjin-Hebei Synergistic Development was elevated to a national strategy in 2014” (lines 609-610), this strategy is still in effect?

In 619-622 you provide some numbers, these are the more recent data available?

In lines 629-630, you mention that there is a “current research on Beijing-Tianjin-Hebei cooperation in air pollution control”, you mean References 48, 49 & 50?

Lines 623-634: From my understanding, the cooperation between Beijing and Hebei helps both regions to develop economically while maintaining emissions. However sooner or later Hebei will have to reduce/control emissions (given the carbon neutrality target), so then what will happen? should there be cooperation with another region with lower economic growth? So is it a "vicious circle"?

In line 650 you mention “while reaching peak emissions as soon as possible”, when these regions reach that point, what will happen then as their economy will depend on higher-carbon emission sectors? When environmental regulations will be applied, they can lead to a significant decline in economic growth, as you state in your paper.

Author Response

Dear Reviewer:

Response to comment 1: This sentence is based on the following policy, already cited in the manuscript: The State Council of the People's Republic of China. Opinions of the Central Committee of the Communist Party of China and the State Council on Completely, Accurately, and Comprehensively Implementing the New Development Concept and Doing a Good Job of Carbon Peak and Carbon Neutrality. 2021. https://www.gov.cn/zhengce/2021-10/24/content_5644613.htm

Response to comment 2: This strategy remains one of China's current national strategies and will continue to be implemented in the long term.

Response to comment 3: All these data come from the China Emission Accounts Datasets (CEADs). CEADs covers emission data of various industries and fields in China, including energy, industry, transport, construction, agriculture, etc., and provides comprehensive emission data statistics and analyses. Meanwhile, it adopts the international common standard of carbon emission statistics, which ensures the comparability and homogeneity of the data. CEADs regularly updates the carbon emission data of each industry and field, reflecting the latest situation of carbon emission in China. The platform has become an important tool for China's carbon emission data release and sharing, providing a scientific basis for environmental protection and carbon emission reduction work. The data are cited from the following sources: Guan, Y.; Shan, Y.; Huang, Q.; Chen, H.; Wang, D.; Hubacek, K. Assessment to China’s recent emission pattern shifts. Earths Future 2021, 9, EF002241. DOI:10.1029/2021EF002241.

Response to comment 4: Thank you for pointing out the ambiguity in this section due to our sloppy writing. In order to make this section clearer to the reader, we have deleted the sentence "This result is consistent with current research on Beijing-Tianjin-Hebei cooperation in air pollution control." because in the latter part of the discussion we have already used the viewpoints of references 49 and 50 to compare with the viewpoints of this paper.

Response to comment 5: Thank you for raising this very thought-provoking question. Our modelling suggests that regional synergies will allow a region to moderately weaken its emissions regulations in the short term, as mentioned in the discussion section on Hebei's emissions growth in the short term, but it is also true that in the long term Hebei will need to meet its emissions reduction targets as soon as possible. Fortunately, as carbon neutrality is a long-term process, the development of renewable energy, carbon sequestration and other technologies will reduce the economic cost of emissions reduction, which will enable Hebei to transform itself into a region with low emissions elasticity or high green total factor productivity in the future, thus breaking out of the "vicious circle". In response to your questions, we have added to the discussion section of the article a description of the limitations of our static, short-term model and the potential for research on long-term development issues.

Response to comment 6: Carbon peaking is a historical turning point where carbon dioxide emissions change from increasing to decreasing, signalling the decoupling of carbon emissions from economic development. In other words, when a region reaches its peak emissions, it means that its regional characteristics, such as emissions elasticity, industrial structure and green total factor productivity, have begun to shift towards a low-carbon development model. At this point, economic growth is no longer dependent on high-emitting industries, and the economic impact of environmental regulation will diminish. We have also included this question in the discussion section. Future research can extend our study with dynamic game and dynamic general equilibrium models to analyse these issues with a long-term, dynamic analytical paradigm.