Politická ekonomie X:X | DOI: 10.18267/j.polek.1510

Environmental Sustainability in Southeast Asia: Evidence from Linear and Nonlinear Unit Root Tests and Policy Implications

Sefa Özbek, Bahar Özbek
Sefa Özbek (corresponding author), Faculty of Applied Sciences, Tarsus University, Mersin, Turkey
Bahar Özbek, School of Graduate Studies, Tarsus University, Mersin, Turkey

This study focuses on Southeast Asian countries that have attracted attention with their recent   economic growth performance. The validity of environmental sustainability is investigated through data for the period 1973–2022. For this purpose, ecological footprint data from Indonesia, the Philippines, Cambodia, Malaysia, Singapore, Thailand and Vietnam are used. Unit root tests with various power properties are used in the study. Firstly, ADF and PP unit root tests based on the Dickey–Fuller unit root test procedure are used in the study. In addition, among the non-linear unit root tests, Leybourne et al. (1998) and Harvey and Mills (2002) unit root tests were used. On the other hand, Hepsağ (2021) unit root test, which includes gradual structural breaks and is among the current non-linear unit root tests, was performed. Results vary depending on unit root tests of different strengths. In general, the validity of environmental sustainability, in other words, convergence, is concluded. These results mostly show the effectiveness of regional and global policies. Some results have revealed that convergence is not valid in some countries, the invalidity of environmental sustainability, and emphasized the effectiveness of national policies

Keywords: Environmental sustainability, convergence, nonlinear unit root, Southeast Asian countries

Received: June 15, 2024; Revised: April 24, 2025; Accepted: May 5, 2025; Prepublished online: December 12, 2025 

Download citation
  • BibTeX (.bib)
  • Bookends (.ris)
  • EasyBib (.ris)
  • EndNote (.enw)
  • EndNote 8 (.xml)
  • ISI WoS (.isi)
  • Medlars (.medlars)
  • Mendeley (.ris)
  • MODS (.xml)
  • Papers (.ris)
  • RefWorks (.txt)
  • RefManager (.ris)
  • RIS (.ris)
  • MS Word (.xml)
  • Zotero (.ris)
    • Open full article

    References

    1. Ahmed, M., Khan, A. M., Bibi, S., and Zakaria, M. (2016). Convergence of per capita CO2 emissions across the globe: Insights via wavelet analysis. Renewable and Sustainable Energy Reviews, 75, 86-97. https://doi.org/10.1016/j.rser.2016.10.053 Go to original source...
    2. Ahmed, Z., and Pata, U. K. (2024). Unveiling the influence of environmental taxes, socioeconomic conditions, renewable energy, and financial globalization on environmental sustainability. In Natural Resources Forum. Oxford, UK: Blackwell Publishing Ltd. https://doi.org/10.1111/1477-8947.12425 Go to original source...
    3. Ali, M., Kirikkaleli, D., and Altuntaş, M. (2024). The nexus between CO2 intensity of GDP and environmental degradation in Southeuropean countries. Environment, Development and Sustainability, 26(5), 11089-11100. https://doi.org/10.1007/s10668-023-03217-w Go to original source...
    4. Alola, A. A., and Ozturk, I. (2021). Mirroring risk to investment within the EKC hypothesis in the United States. Journal of Environmental Management, 293, 112890. https://doi.org/10.1016/j.jenvman.2021.112890 Go to original source...
    5. Altintaş, H., and Kassouri, Y. (2020). Is the environmental Kuznets Curve in Europe related to the per-capita ecological footprint or CO2 emissions?. Ecological Indicators, 113, 106187. https://doi.org/10.1016/j.ecolind.2020.106187 Go to original source...
    6. Aslan, A., Ilhan, O., Usama, A. M., Savranlar, B., Polat, M. A., Metawa, N., & Raboshuk, A. (2024). Effect of economic policy uncertainty on CO2 with the discrimination of renewable and non renewable energy consumption. Energy, 291, 130382. https://doi.org/10.1016/j.energy.2024.130382 Go to original source...
    7. Balsalobre-Lorente, D., Ibáñez-Luzón, L., Usman, M., and Shahbaz, M. (2022). The environmental Kuznets curve, based on the economic complexity, and the pollution haven hypothesis in PIIGS countries. Renewable Energy, 185, 1441-1455. https://doi.org/10.1016/j.renene.2021.10.059 Go to original source...
    8. Bilgili, F., and Ulucak, R. (2018). Is There Deterministic, Stochastic, and/or Club Convergence in Ecological Footprint Indicator among G20 Countries?. Environmental Science and Pollution Research, 25(35), 35404-35419. https://doi.org/10.1007/s11356-018-3457-1 Go to original source...
    9. Cai, Y., Chang, T., and Inglesi-Lotz, R. (2018). Asymmetric Persistence in Convergence for Carbon Dioxide Emissions Based on Quantile Unit Root Test with Fourier Function. Energy, 161, 470-481. https://doi.org/10.1016/j.energy.2018.07.125 Go to original source...
    10. D'Orazio, P., Schäfer, D., and Stephan, A. (2024). Macro-financial policy at the crossroad: addressing climate change, biodiversity loss, and environmental degradation-introduction to the special issue. Eurasian Economic Review, 14(1), 1-11. https://doi.org/10.1007/s40822-024-00265-z Go to original source...
    11. Dickey, D. A., and Fuller, W. A. (1979). Distribution of the estimators for autoregressive time series with a unit root. Journal of the American Statistical Association, 74(366a), 427-431. https://doi.org/10.1080/01621459.1979.10482531 Go to original source...
    12. Dickey, D. A., and Fuller, W. A. (1981). Likelihood ratio statistics for autoregressive time series with a unit root. Econometrica: Journal of the Econometric Society, 1057-1072. https://doi.org/10.2307/1912517 Go to original source...
    13. Erdogan, S., Ahmed, M. Y., and Sarkodie, S. A. (2022). Analyzing asymmetric effects of cryptocurrency demand on environmental sustainability. Environmental Science and Pollution Research, 29(21), 31723-31733. https://doi.org/10.1007/s11356-021-17998-y Go to original source...
    14. Erdogan, S., and Okumus, I. (2021). Stochastic and Club Convergence of Ecological Footprint: An Empirical Analysis for Different Income Group of Countries. Ecological Indicators, 121, 107123. https://doi.org/10.1016/j.ecolind.2020.107123 Go to original source...
    15. Gil-Alana, L. A., and Solarin, S. A. (2018). Have US Environmental Policies been Effective in the Reduction of US Emissions? A new Approach Using Fractional Integration. Atmospheric Pollution Research, 9(1), 53-60. https://doi.org/10.1016/j.apr.2017.06.008 Go to original source...
    16. Gil-Alana, L. A., Cunado, J., and Gupta, R. (2017). Persistence, Mean-Reversion and Nonlinearities in CO2 Emissions: Evidence from the BRICS and G7 Countries. Environmental Resource Economics, 67(4), 869-883. https://doi.org/10.1007/s10640-016-0009-3 Go to original source...
    17. Global Footprint Network. (2024). Ecological Footprint. Retrieved from https://www.footprintnetwork.org/ (Accessed: 02.03.2024).
    18. Guo, J., Zhou, Y., Ali, S., Shahzad, U., and Cui, L. (2021). Exploring the role of green innovation and investment in energy for environmental quality: An empirical appraisal from provincial data of China. Journal of Environmental Management, 292, 112779. https://doi.org/10.1016/j.jenvman.2021.112779 Go to original source...
    19. Güler, İ., Naimoğlu, M., Şimşek, O., Adali, Z., and Özbek, S. (2025). Analyzing the impact of economic growth and FDI on sustainable development goals in China: insights from ecological footprints and load capacity factors. Frontiers in Environmental Science, 13, 1513158. https://doi.org/10.3389/fenvs.2025.1513158 Go to original source...
    20. Güzel, A. E., & Okumuş, İ. (2020). Revisiting the pollution haven hypothesis in ASEAN-5 countries: new insights from panel data analysis. Environmental Science and Pollution Research, 27, 18157-18167. https://doi.org/10.1007/s11356-020-08317-y Go to original source...
    21. Harvey, D. I., and Leybourne, S. J. (2007). Testing for time series linearity. The Econometrics Journal, 10(1), 149-165. https://doi.org/10.1111/j.1368-423X.2007.00203.x Go to original source...
    22. Harvey, D. I., and Mills, T. C. (2002). Unit roots and double smooth transitions. Journal of Applied Statistics, 29(5), 675-683. https://doi.org/10.1080/02664760120098739 Go to original source...
    23. Heil, M. T., and Selden, T. M. (1999). Panel Stationarity with Structural Breaks: Carbon Emissions and GDP. Applied Economics Letters, 6(4), 223-225. https://doi.org/10.1080/135048599353384 Go to original source...
    24. Hepsag, A. (2021). A unit root test based on smooth transitions and nonlinear adjustment. Communications in Statistics-Simulation and Computation, 50(3), 625-632. https://doi.org/10.1080/03610918.2018.1563154 Go to original source...
    25. IEA. (2024). [Online]. Available: https://www.iea.org/data-and-statistics. Accessed: 02.03.2024.
    26. IEA. (2024). Energy Statistics. [Online]. Available: https://www.iea.org/data-and-statistics. Accessed: 03.02.2024.
    27. IMF-International Monetary Fund (2024). [Online]. Available: https://www.imf.org/en/Home. Accessed: 02.03.2024.
    28. Işik, C., Ahmad, M., Ongan, S., Özdemir, D., Irfan, M., and Alvarado, R. (2021). Convergence Analysis of The Ecological Footprint: Theory and Empirical Evidence from The USMCA Countries. Environmental Science and Pollution Research, 1-12. https://doi.org/10.1007/s11356-021-12993-9 Go to original source...
    29. Kasahun, M. (2025). Quantifying deforestation drivers through multi-temporal LULC Analysis and population-forest correlation modeling: a case study of Dara Woreda, Ethiopia. Environmental Challenges, 101163. https://doi.org/10.1016/j.envc.2025.101163 Go to original source...
    30. Kearsley, A., and Riddel, M. (2010). A further inquiry into the pollution haven hypothesis and the environmental Kuznets curve. Ecological Economics, 69(4), 905-919. https://doi.org/10.1016/j.ecolecon.2009.11.014 Go to original source...
    31. Lee, C. C., and Chang, C. P. (2009). Stochastic Convergence of Per Capita Carbon Dioxide Emissions and Multiple Structural Breaks in OECD countries. Economic Modelling, 26(6), 1375-1381. https://doi.org/10.1016/j.econmod.2009.07.003 Go to original source...
    32. Leybourne, S. J., Newbold, P., and Vougas, D. (1998). "Unit Roots and Smooth Transitions". Journal of Time Series Analysis, 19, 83-97. https://doi.org/10.1111/1467-9892.00078 Go to original source...
    33. List, J., and Strazicich, M. (2003). Are CO2 Emission Levels Converging among Industrial Countries? Environmental and Resource Economics, 24, 263-271. https://link.springer.com/article/10.1023/A:1022910701857 Go to original source...
    34. Makarov, I., and Alataş, S. (2024). Production-and consumption-based emissions in carbon exporters and importers: A large panel data analysis for the EKC hypothesis. Applied Energy, 363, 123063. https://doi.org/10.1016/j.apenergy.2024.123063 Go to original source...
    35. Mert, M., and Bölük, G. (2016). Do foreign direct investment and renewable energy consumption affect CO2 emissions? New evidence from a panel ARDL approach to Kyoto Annex countries. Environmental Science and Pollution Research, 23(19), 21669-21681. https://doi.org/10.1007/s11356-016-7413-7 Go to original source...
    36. Naimoğlu, M., and Özbek, S. (2022). Testing The Environmental Kuznets Curve Hypothesis under Structural Breaks: The Case of Turkey. Alanya Akademik Bakiş, 6(3), 3069-3084. https://doi.org/10.29023/alanyaakademik.992079 Go to original source...
    37. Nguyen, T. T. H., Tu, Y. T., Diep, G. L., Tran, T. K., Tien, N. H., and Chien, F. (2023). Impact of natural resources extraction and energy consumption on environmental sustainability in ASEAN countries. Resources Policy, 85, 103713. https://doi.org/10.1016/j.resourpol.2023.103713 Go to original source...
    38. Ogunbode, C. A., Doran, R., and Böhm, G. (2020). Exposure to the IPCC special report on 1.5°C global warming is linked to perceived threat and increased concern about climate change. Climatic Change, 158, 361-375. https://doi.org/10.1007/s10584-019-02609-0 Go to original source...
    39. Oğul, B. (2023). Tarim Sektöründeki Gelişmeler Çevresel Kirliliğini Etkiliyor mu? Türkiye Üzerine Ampirik Bulgular. MANAS Sosyal Araştirmalar Dergisi, 12(3), 1016-1026. https://doi.org/10.33206/mjss.1063110 Go to original source...
    40. Ojogiwa, O. T. (2021). The crux of strategic leadership for a transformed public sector management in Nigeria. International Journal of Business and Management Studies, 13(1), 83-96. https://doi.org/10.48080/ijbms.20210105 Go to original source...
    41. Özbek, S., & Naimoğlu, M. (2025). The effectiveness of renewable energy technology under the EKC hypothesis and the impact of fossil and nuclear energy investments on the UK's Ecological Footprint. Energy, 322, 135351. https://doi.org/10.1016/j.energy.2025.135351 Go to original source...
    42. Özbek, S., and Naimoğlu, M. (2022). Çevre kalitesi-ekonomik karmaşiklik ilişkisi: Türkiye ekonomisi üzerine fourier eşbütünleşme analizi. İstanbul İktisat Dergisi, 72(1), 407-431. https://doi.org/10.26650/ISTJECON2022-1061837 Go to original source...
    43. Özcan, B., Ulucak, R., and Doğan, E. (2019). Analyzing Long Lasting Effects of Environmental Policies: Evidence from Low-, Middle- and High-Income Economies. Sustainable Cities and Society, 44, 130-143. https://doi.org/10.1016/j.scs.2018.09.025 Go to original source...
    44. Panopoulou, E., and Pantelidis, T. (2007). Club Convergence in Carbon Dioxide Emissions. The Institute for International Integration Studies Discussion Paper Series iiisdp235. https://doi.org/10.1007/s10640-008-9260-6 Go to original source...
    45. Pata, U. K., & Aydin, M. (2023). Persistence of CO2 emissions in G7 countries: a different outlook from wavelet-based linear and nonlinear unit root tests. Environmental Science and Pollution Research, 30(6), 15267-15281. https://doi.org/10.1007/s11356-022-23284-2 Go to original source...
    46. Pata, U. K., & Yilanci, V. (2021). Investigating the persistence of shocks on the ecological balance: evidence from G10 and N11 countries. Sustainable Production and Consumption, 28, 624-636. https://doi.org/10.1016/j.spc.2021.06.027 Go to original source...
    47. Pata, U. K., Naimoglu, M., Karlilar, S., and Kartal, M. T. (2024). Analyzing the EKC hypothesis for the top 10 energy-importing countries: a perspective for the COP27 targets. Air Quality, Atmosphere & Health, 17(5), 953-966. https://doi.org/10.1007/s11869-023-01490-2 Go to original source...
    48. Phillips, P. C., and Perron, P. (1988). Testing for a unit root in time series regression. Biometrika, 75(2), 335-346. https://doi.org/10.1093/biomet/75.2.335 Go to original source...
    49. Phillips, P. C., and Sul, D. (2007). Transition modeling and econometric convergence tests. Econometrica, 75(6), 1771-1855. https://doi.org/10.1111/j.1468-0262.2007.00811.x Go to original source...
    50. Qiu, J., Seah, S., & Martinus, M. (2024). Examining climate ambition enhancement in ASEAN countries' nationally determined contributions. Environmental Development, 49, 100945. https://doi.org/10.1016/j.envdev.2023.100945 Go to original source...
    51. Smoot, L. D., and Baxter, L. L. (2003). Fossil fuel power stations-coal utilization. Encyclopedia of Physical Science and Technology (Third Edition). Retrieved from https://www.sciencedirect.com/topics/earth-and-planetary-sciences/greenhouse-gas-emission. Accessed: 04.04.2024. Go to original source...
    52. Solarin, S. A., Tiwari, A. K., and Bello, M. O. (2019). A multi-country convergence analysis of ecological footprint and its components. Sustainable Cities and Society, 46, 101422. https://doi.org/10.1016/j.scs.2019.101422 Go to original source...
    53. Stegman, A. (2005). Convergence in Carbon Emissions Per Capita. Macquarie: Department of Economics, Macquarie University. https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=f8da43b3fd77b64df1b3273631cc3fd88225eed8 Accessed: 04.03.2024.
    54. Tatar, H. E. (2022). Asean-5 Ülkelerinde Ekolojik Ayak İzi Yansimasi: SURADF ve SURKSS Birim Kök Testi. Fiscaoeconomia, 6(3), 1018-1035. https://doi.org/10.25295/fsecon1071194 Go to original source...
    55. Tiwari, A. K., Kyophilavong, P., & Albulescu, C. T. (2016). Testing the Stationarity of CO2 Emissions Series in Sub-Saharan African Countries by Incorporating Nonlinearity and Smooth Breaks. Research in International Business and Finance, 37, 527-540. https://doi.org/10.1016/j.ribaf.2016.01.005 Go to original source...
    56. Ullah, S., and Lin, B. (2024). Harnessing the synergistic impacts of financial structure, industrialization, and ecological footprint through the lens of the EKC hypothesis. Insights from Pakistan. Energy, 307, 132540. https://doi.org/10.1016/j.energy.2024.132540 Go to original source...
    57. Ulucak, R. (2017). Çevre kalitesi açisindan yakinsama hipotezine yeni bir bakiş: ekolojik ayak izi ve kulüp yakinsamaya dayali ampirik bir analiz. Anadolu Üniversitesi Sosyal Bilimler Dergisi, 18(4), 29-38. https://doi.org/10.18037/ausbd.552674 Go to original source...
    58. Ursavaş, N., & Apaydin, Ş. (2023). The Convergence in Greenhouse Gas Emissions Across G-7 Countries. Fiscaoeconomia, 7(1), 327-340. https://doi.org/10.25295/fsecon.1143345 Go to original source...
    59. Yilanci, V., & Pata, U. K. (2020a). Convergence of Per Capita Ecological Footprint Among The ASEAN-5 Countries: Evidence from A Non-Linear Panel Unit Root Test. Ecological Indicators, 113, 106178. https://doi.org/10.1016/j.ecolind.2020.106178 Go to original source...
    60. Yilanci, V., Görüş, M. S., & Solarin, S. A. (2021). Convergence In Per Capita Carbon Footprint and Ecological Footprint For G7 Countries: Evidence From Panel Fourier Threshold Unit Root Test. Energy & Environment, 0958305X211011461. https://doi.org/10.1177/0958305X211011461 Go to original source...
    61. Yilanci, V., & Pata, U. K. (2020b). Are shocks to ecological balance permanent or temporary? Evidence from LM unit root tests. Journal of Cleaner Production, 276, 124294. https://doi.org/10.1016/j.jclepro.2020.124294 Go to original source...
    62. Yurtkuran, S. (2020). N11 ülkelerinde ekolojik ayak izi yakinsamasi: Fourier durağanlik testinden yeni kanitlar. Uluslararasi Ekonomi ve Yenilik Dergisi, 6(2), 191-210. https://doi.org/10.20979/ueyd.681354 Go to original source...
    63. Zhang, J., Hao, X., Li, X., Fan, X., & Zhang, S. (2024). Evaluation and regulation strategy for ecological security in the Tarim River Basin based on the ecological footprint. Journal of Cleaner Production, 435, 140488. https://doi.org/10.1016/j.jclepro.2023.140488 Go to original source...

    This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY NC ND 4.0), which permits non-comercial use, distribution, and reproduction in any medium, provided the original publication is properly cited. No use, distribution or reproduction is permitted which does not comply with these terms.


    Return