Decoupling CO2 Emissions from Economic Growth in China’s Cities from 2000 to 2020: A Case Study of the Pearl River Delta Agglomeration
Round 1
Reviewer 1 Report
The paper of CO2 and economic growth decoupling for the PRD agglomeration is very interesting. The authors use the Tapio methodology for CO2 and economic growth decoupling and examined nine urban areas. Results revealed significant volatility between the examined areas.
This is a very interesting study. Although this paper is well written, I have some suggestions that I believe will further improve the final manuscript.
1)Concerning the introduction section, I would propose to create a couple of paragraphs and discuss more about the relation of energy consumption, CO2 emissions and economic growth with an international perspective. This should be placed before the theory for decoupling. You may consider using some of the proposed relevant studies for CO2 and economic growth such as: 1) Chontanawat J., Hunt L., Pierse R. (2008). Does energy consumption cause economic growth: evidence from a systematic study of over 100 countries, Journal of Policy Model, Vol.30, pp. 209–220. 2) Bella G., Massidda C., Mattana P. (2014). The relationship among CO2 emissions, electricity power consumption and GDP in OECD countries, Journal of Policy Modeling, Vol. 36, pp. 970–985. 3) Ntanos, S.; Arabatzis, G.; Milioris, K.; Chalikias, M.; Lalou, P. Energy Consumption and CO2 Emissions on a Global Level. In Proceedings of the 4th International Conference: Quantitative and Qualitative Methodologies in the Economic & Administrative Sciences (ICQQMEAS 2015); Technological Education Institute of Athens: Athens, Greece, 2015; pp. 251–260
2) I propose that you further expand your discussion and conclusions section. An important variable for CO2 decoupling in urban setting is the urbanization rate. See for example a recent study for China https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926756/. I would like to add in your discussion section some implications and thoughts of this variable of urbanization rate to better explain your results. Moreover, variables such as city size, economic development, social system, and technological progress and their impact on CO2 emission decoupling could be discussed.
3) Furthermore I would propose to mention in the recommendations for future research the possible verification of your results by applying a regression model. Also I suggest that you may put a couple of lines for policy implications in more detail.
Language level is ok, I would propose a final check for grammar and expressions.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript aims to explore the decoupling relationship between economic growth and CO2 emissions of the Pearl River Delta urban agglomeration, using the data from 2000 to 2020 and Tapio decoupling model. The topic is relevant to the journal of Sustainability. Overall, the method and data are clearly explained, the empirical results are reported logically, and the discussion and conclusions are supported by the results. However, in presentation, this manuscript can be largely improved in organization, results analysis and discussion depth, clarity, and readability. A few recommendations for improvement are listed below.
1. Title and Abstract:
(1) Abstract: The authors need to present the most significant and interesting results concisely. Just direct present the decoupling results and highlight the major findings, but not detailly illustrate the spatial distribution of energy consumption and CO2 emissions in PRD region, i.e., “The findings reveal that the PRD urban agglomeration has significant differences in energy consumption and CO2 emissions. The spatial pattern of total CO2 emissions is high in the center and low on the periphery. In contrast, the spatial distribution pattern of CO2 intensity has lower intensity in the central areas and higher intensity in the peripheral areas.”, which are common knowledge to the academia.
(2) Abstract: The empirical results or findings should be organized clearly, i.e., use (1), (2), and (3), respectively.
2. Introduction and Literature Review:
(1) The introduction is well organized in general. However, the practical background of PRD region, i.e., the status of CO2 and economy and why decoupling development is significant for PRD agglomeration, should be illustrated for readers. Thus, I suggest the section “2.1. Study area” can be placed in this section. You need only analyze the agglomeration in depth but not China.
(2) The literature review of the study can be improved and enriched. Especially on regional economic development and carbon emissions, some works had examined the relationship for China’s provinces using the decomposition methods, as the authors done. For example, “Who shapes China's carbon intensity and how? A demand-side decomposition analysis. Energy Economics, 2020”, “Regional embodied carbon emissions and their transfer characteristics in China, 2018”, etc. Please review these studies and justify the contributions of your work.
(3) In the last paragraph of the introduction, the authors claimed the contribution and novelty of this study. However, the two contributions are marginal and look pretty much the same, i.e., urban agglomerations perspective. Are there any innovations in decoupling models and methods? Especially for urban agglomeration areas and other regional levels, what are the differences? Please highlight your contributions to the literature and new knowledge.
3. Methodology and Data
(1) The decoupling states described in Table 1 are general knowledge for decoupling anlaysis scholars, thus don’t need to elaborate.
(2) The authors should add one section describing the detail of decoupling decomposition method, which were used in the following Table 3.
4. Results and discussion:
(1) The organization of this section is not reasonable. The authors have devoted a considerable amount of space to providing a detailed introduction to the energy consumption, energy intensity, carbon emissions, carbon intensity, and per capita carbon emissions of various cities in the Pearl River Delta. However, the discussion on the decoupling relationship between carbon emissions and economic development in cities in the Pearl River Delta (also the title of the article) only includes three or four paragraphs.
(2) Therefore, it is recommended to delete some irrelevant content in section 3.1, such as energy consumption, energy intensity, per capita carbon emissions, and only retain indicators such as carbon emissions, GDP, and carbon intensity.
(3) At the same time, expand the content of section 3.2 to deeply analyze the changes in decoupling status and their driving factors.
(4) The authors should analyze and discuss the results thoroughly. The authors could make some comparative analyses with previous studies.
(5) In addition, the authors limited their discussions to the results, but not extended to the practical background of China’s urban agglomerations, regional decoupling development, and carbon emissions. This weakens the significance of this study.
5. Conclusions and policy implications
(1) The main findings, as well as policy implications, should be presented more clearly in separated paragraphs in conclusions. For example, first, second, third, and so on.
(2) The policy implications can be refined. Tell how to do but not should do what.
There are some grammar and typo mistakes in this manuscript. Please ask some native English writers to help you improve this paper.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear Authors,
I have carefully reviewed the changes made in response to the previous reviewer comments, and I am pleased to see that you have addressed them satisfactorily. The quality of the manuscript has significantly improved in organization, results analysis, and readability. I am satisfied with all amendments.
Good luck with your publication!
