CO2 Emissions, Energy Consumption, and Economic Growth: New Evidence in the ASEAN Countries
Round 1
Reviewer 1 Report
Why did you use only one unit-root test? For the purpose of robustness, use several more unit-root tests. Also, try using the so-called bootstrap causality test just to see if the results are compatibile since bootstrap causality test is also applicable when dealing with (relatively) small samples. Also, run a battery of diagnostic tests to confirm the robustness of your causality results.
Author Response
Responses to Reviewer 1 Comments
Why did you use only one unit-root test? For the purpose of robustness, use several more unit-root tests. Also, try using the so-called bootstrap causality test just to see if the results are compatible since bootstrap causality test is also applicable when dealing with (relatively) small samples. Also, run a battery of diagnostic tests to confirm the robustness of your causality results.
Response: Thank you very much for your comments. We have updated Table 2 with two unit-root tests, namely Augmented Dickey-Fuller (ADF) and Phillips Pearson (PP) tests, together with the current one, the Dickey Fuller Generalized Least Square (DF-GLS). As such, as presented in Table 2 in relation to the results of unit root test, three comparable tests show a consistent conclusion in the order of integration among selected variables.
Also, we want to thank the referee for a helpful comment in relation to the issue of a relatively small sample of data. We have greatly appreciated this comment. In the revised version of the paper, we acknowledge this suggestion as a useful and excellent point to be considered in the future. We are on the view that using the so-call bootstrap causality will open a potential debate for future research not only to test our results but also other previous studies.
Reviewer 2 Report
This is a very interesting paper that is well written and presented. The authors seem to have made efforts to ensure adequate discussion and robustness checks. Although, the overall topic is not new, the addition of renewable energy into the EKC framework is interesting.
However, some improvements need to be made before the paper can be published. I list them here.
· The literature review section completely ignored the non-parametric strand of the literature that can possibly explain the mixed results in the EKC literature. For example, Arouri et al. (2012) find evidence of EKC relationship in the MENA region, while Fakih and Marrouch (2019) using the same data find no such evidence when employing a non-parametric approach.
· Equation (1) can be better motivated by referring to the scale, technique, and composition effects (see Stern, 2004)
· Table 1 reports negative values! Taking the logarithm of the variables having values between zero and one.
· In equation (2), it is not clear if the variables are logged or at level.
· The discussion of the sign of alpha 2 on page 22 is not sufficient to conclude that an EKC relationship exists or not. See Wang (2013)
· It would be useful to summarize the rich set of results in a table as ‘take home message’ for the readers
· Clarifications: line 50, compared to which year/level? On page 7, it is not mentioned which pollutant is studied.
· Typos: line 9-10, line 31,
References:
Arouri, M. E. H., A. Ben Youssef, H. M’henni, & C. Rault (2012) “Energy consumption, economic growth and CO2 emissions in Middle East and North African countries” Energy Policy 45, 342-49.
Fakih, A., & Marrouch, W. (2019). Environmental Kuznets curve, a mirage? A Non-parametric analysis for MENA countries. International Advances in Economic Research 25, 113–119.
Stern, D.I. (2004). The rise and fall of the environmental Kuznets curve. World Development 32, 1419-39.
Wang, Y.C. (2013). Functional sensitivity of testing the environmental Kuznets curve hypothesis. Resource and Energy Economics 35, 451-466.
Author Response
Responses to Reviewer 2 Comments
This is a very interesting paper that is well written and presented. The authors seem to have made efforts to ensure adequate discussion and robustness checks. Although, the overall topic is not new, the addition of renewable energy into the EKC framework is interesting. However, some improvements need to be made before the paper can be published. I list them here.
Response: Thank you for all the above comments. Your encouragements are appreciated. We have made the adjustments as suggested in the revised version.
The literature review section completely ignored the non-parametric strand of the literature that can possibly explain the mixed results in the EKC literature. For example, Arouri et al. (2012) find evidence of EKC relationship in the MENA region, while Fakih and Marrouch (2019) using the same data find no such evidence when employing a non-parametric approach.Response: Thank you very much for your comments. Please be advised that a new paragraph, which is highlighted in blue in the session of Literature review, is added to indicate the nonparametric strand of the EKC literature.
Equation (1) can be better motivated by referring to the scale, technique, and composition effects (see Stern, 2004)
Response: Thank you very much for your comments. Equation (1) is elaborated with the helpful suggestion. We clearly explain the scale, technique, and composition effects (see Stern, 2004) in the revised version.
Table 1 reports negative values! Taking the logarithm of the variables having values between zero and one.
Response: Thank you very much for your comments. We have rescaled all the variables so that a number of values falls between zero and one. As such, these values are negative when taking the logarithm.
In equation (2), it is not clear if the variables are logged or at level.
Response: Thank you very much for your comments. We made a clarification for equation 2 in the revised version.
The discussion of the sign of alpha 2 on page 22 is not sufficient to conclude that an EKC relationship exists or not. See Wang (2013)
Response: Thank you very much for your comments. We have now presented a clearer discussion with a note that explains the appropriateness of the current analysis without suffering a spurious regression.
It would be useful to summarize the rich set of results in a table as ‘take home message’ for the readers
Response: We noted this comment. We outlined our results of the causality test vividly for the readers, but we are on the view that it should be better to clearly present the results rather than using a table.
Clarifications: line 50, compared to which year/level? On page 7, it is not mentioned which pollutant is studied. Typos: line 9-10, line 31.
Response: Thank you very much for your comments. We fixed all the errors in the revised version of the paper.
Reviewer 3 Report
The paper deals with the common hypothesis regarding a long-run environmental Kuznets curve (EKC) investigate the causal link between carbon dioxide (CO2) emissions, energy consumption, renewable energy, population growth, and economic growth. The study is applied to ASEAN region. The main weakness of this paper is the lack of novelty. There are many studies dealing with Kuznets curve (EKC) hypothesis in ASEAN region as well. There are no obvious strengths in this paper. The authors first of all need to highlighted why have they decided to conduct this study. The lack of scientific problem in the paper causes other problems. The discussion of results and comparison with similar studies is not presented in this paper showing the main weaknesses of this manuscript. Due to the lack of novelty I recommend authors to put more effort on this manuscript and define scientific problem and address the novelty. The methods applied should be based on theoretical basis. The strengths and weaknesses of applied methods should be addressed including limitations of this study. The authors should think about policy implication of conducted study. How these results can be useful for ASEA countries etc. The current version of paper can't be published. Major revision is necessary.
Author Response
The paper deals with the common hypothesis regarding a long-run environmental Kuznets curve (EKC) investigate the causal link between carbon dioxide (CO2) emissions, energy consumption, renewable energy, population growth, and economic growth. The study is applied to ASEAN region.
The main weakness of this paper is the lack of novelty. There are many studies dealing with Kuznets curve (EKC) hypothesis in ASEAN region as well. There are no obvious strengths in this paper. The authors first of all need to highlighted why have they decided to conduct this study.Response: Thank you very much for your comment. We added various new paragraphs in the revised version of the paper, which are highlighted in blue in the session of Introduction, to highlight the significant contribution of the current research to the current literature.
The lack of scientific problem in the paper causes other problems. The discussion of results and comparison with similar studies is not presented in this paper showing the main weaknesses of this manuscript. Due to the lack of novelty I recommend authors to put more effort on this manuscript and define scientific problem and address the novelty.
Response: Thank you very much for your comment. Please be advised that two new paragraphs, which are highlighted in blue in the “Empirical Results and Discussions” section, are added to indicate the similarity and difference of results between our research and other studies in the region.
The methods applied should be based on theoretical basis. The strengths and weaknesses of applied methods should be addressed including limitations of this study.
Response: Thank you very much for your comment. Please be advised that we have now provided detailed justifications on the baseline model using the argument from Stern (2004). We also discuss the weakness of the research in relation to a relatively small sample in the causality test by adding two new paragraphs, which are highlighted in blue in the session of Concluding remarks.
The authors should think about policy implication of conducted study. How these results can be useful for ASEA countries etc. The current version of paper can't be published. Major revision is necessary.
Response: Thank you very much for your comment. We responded this comment by adding two new paragraphs, which are highlighted in blue in the session of Concluding remarks, in order to illustrate policy implications for academic research and public policy. The Conclusion is now enhanced with this line of clarification. We thank the reviewers for this constructive and thoughtful comment.
Round 2
Reviewer 2 Report
The authors have satisfactorily addressed all my comments. I have no further comments.
Author Response
We would like to thank the referee for his/her time and constructive comments towards the improvement of our manuscript.
Reviewer 3 Report
The authors have incorporated my comments and improved paper. I do not have more remarks. The paper can be published in current form.
Author Response
We are grateful for your constructive comments and suggestions towards the improvement of our manuscript.
