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Exploring the relationship among CO2 emissions, real GDP, energy consumption and tourism in the EU and candidate countries: Evidence from panel models robust to heterogeneity and cross-sectional dependence

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  • Dogan, Eyup
  • Aslan, Alper
Abstract
A major criticism to the existing energy-growth-environment literature, we notice, is the selection of methodology. Panel estimation techniques that fail to consider both heterogeneity and cross-sectional dependence across countries may cause forecasting errors. The other concern related to the literature is that only a small number of studies analyze the influence of tourism on CO2 emissions even though tourism sector has potential for affecting the environment. To fulfill the mentioned gaps in the literature, this study analyzes the relationship among carbon emissions, real income, energy consumption and tourism for a panel of the EU and candidate countries over the period 1995–2011 by using heterogeneous panel estimation techniques with cross-sectional dependence. Results from the CADF and the CIPS panel unit root tests show that the analyzed variables become stationary at their first-differences. The LM bootstrap panel cointegration test indicates the presence of a long run relationship among the analyzed variables. Results from the OLS with fixed effects, the FMOLS, the DOLS and the group-mean estimator reveal that energy consumption contributes to the level of emissions while real income and tourism mitigate CO2 emissions. The Emirmahmutoglu-Kose panel Granger causality test suggests that there is one-way causality running from tourism to carbon emissions, and two-way causality between CO2 emissions and energy consumption, and between real income and CO2 emissions. Policy implications are further discussed.

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  • Dogan, Eyup & Aslan, Alper, 2017. "Exploring the relationship among CO2 emissions, real GDP, energy consumption and tourism in the EU and candidate countries: Evidence from panel models robust to heterogeneity and cross-sectional depen," Renewable and Sustainable Energy Reviews, Elsevier, vol. 77(C), pages 239-245.
    • Handle: RePEc:eee:rensus:v:77:y:2017:i:c:p:239-245
    DOI: 10.1016/j.rser.2017.03.111
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    1. Say, Nuriye Peker & Yucel, Muzaffer, 2006. "Energy consumption and CO2 emissions in Turkey: Empirical analysis and future projection based on an economic growth," Energy Policy, Elsevier, vol. 34(18), pages 3870-3876, December.
    2. Pao, Hsiao-Tien & Yu, Hsiao-Cheng & Yang, Yeou-Herng, 2011. "Modeling the CO2 emissions, energy use, and economic growth in Russia," Energy, Elsevier, vol. 36(8), pages 5094-5100.
    3. Zhang, Lei & Gao, Jing, 2016. "Exploring the effects of international tourism on China's economic growth, energy consumption and environmental pollution: Evidence from a regional panel analysis," Renewable and Sustainable Energy Reviews, Elsevier, vol. 53(C), pages 225-234.
    4. Farhani, Sahbi & Chaibi, Anissa & Rault, Christophe, 2014. "CO2 emissions, output, energy consumption, and trade in Tunisia," Economic Modelling, Elsevier, vol. 38(C), pages 426-434.
    5. Lee, Jung Wan & Brahmasrene, Tantatape, 2013. "Investigating the influence of tourism on economic growth and carbon emissions: Evidence from panel analysis of the European Union," Tourism Management, Elsevier, vol. 38(C), pages 69-76.
    6. Dagher, Leila & Yacoubian, Talar, 2012. "The causal relationship between energy consumption and economic growth in Lebanon," Energy Policy, Elsevier, vol. 50(C), pages 795-801.
    7. Westerlund, Joakim & Edgerton, David L., 2007. "A panel bootstrap cointegration test," Economics Letters, Elsevier, vol. 97(3), pages 185-190, December.
    8. M. Hashem Pesaran, 2021. "General diagnostic tests for cross-sectional dependence in panels," Empirical Economics, Springer, vol. 60(1), pages 13-50, January.
    9. Hashem Pesaran, M. & Yamagata, Takashi, 2008. "Testing slope homogeneity in large panels," Journal of Econometrics, Elsevier, vol. 142(1), pages 50-93, January.
    10. Esteve, Vicente & Tamarit, Cecilio, 2012. "Threshold cointegration and nonlinear adjustment between CO2 and income: The Environmental Kuznets Curve in Spain, 1857–2007," Energy Economics, Elsevier, vol. 34(6), pages 2148-2156.
    11. Asafu-Adjaye, John, 2000. "The relationship between energy consumption, energy prices and economic growth: time series evidence from Asian developing countries," Energy Economics, Elsevier, vol. 22(6), pages 615-625, December.
    12. Usama Al-Mulali & Ilhan Ozturk & Hooi Lean, 2015. "The influence of economic growth, urbanization, trade openness, financial development, and renewable energy on pollution in Europe," Natural Hazards: Journal of the International Society for the Prevention and Mitigation of Natural Hazards, Springer;International Society for the Prevention and Mitigation of Natural Hazards, vol. 79(1), pages 621-644, October.
    13. E. Çaglayan & N. Sak & K. Karymshakov, 2012. "Relationship between Tourism and Economic Growth: A Panel Granger Causality Approach," Asian Economic and Financial Review, Asian Economic and Social Society, vol. 2(5), pages 591-602, September.
    14. Iwata, Hiroki & Okada, Keisuke & Samreth, Sovannroeun, 2010. "Empirical study on the environmental Kuznets curve for CO2 in France: The role of nuclear energy," Energy Policy, Elsevier, vol. 38(8), pages 4057-4063, August.
    15. Javid, Muhammad & Sharif, Fatima, 2016. "Environmental Kuznets curve and financial development in Pakistan," Renewable and Sustainable Energy Reviews, Elsevier, vol. 54(C), pages 406-414.
    16. Irina Dolgopolova & Qazi Hye & Iyala Stewart, 2014. "Energy consumption and economic growth: evidence from non-OPEC oil producing states," Quality & Quantity: International Journal of Methodology, Springer, vol. 48(2), pages 887-898, March.
    17. Peter Pedroni, 2000. "Fully Modified OLS for Heterogeneous Cointegrated Panels," Department of Economics Working Papers 2000-03, Department of Economics, Williams College.
    18. Im, Kyung So & Pesaran, M. Hashem & Shin, Yongcheol, 2003. "Testing for unit roots in heterogeneous panels," Journal of Econometrics, Elsevier, vol. 115(1), pages 53-74, July.
    19. Salih Katircioglu, 2009. "Tourism, trade and growth: the case of Cyprus," Applied Economics, Taylor & Francis Journals, vol. 41(21), pages 2741-2750.
    20. Narayan, Paresh Kumar & Prasad, Arti, 2008. "Electricity consumption-real GDP causality nexus: Evidence from a bootstrapped causality test for 30 OECD countries," Energy Policy, Elsevier, vol. 36(2), pages 910-918, February.
    21. Acaravci, Ali & Ozturk, Ilhan, 2010. "On the relationship between energy consumption, CO2 emissions and economic growth in Europe," Energy, Elsevier, vol. 35(12), pages 5412-5420.
    22. repec:ipg:wpaper:201415 is not listed on IDEAS
    23. Ang, James B., 2007. "CO2 emissions, energy consumption, and output in France," Energy Policy, Elsevier, vol. 35(10), pages 4772-4778, October.
    24. Ozturk, Ilhan, 2010. "A literature survey on energy-growth nexus," Energy Policy, Elsevier, vol. 38(1), pages 340-349, January.
    25. Katircioglu, Salih Turan, 2014. "International tourism, energy consumption, and environmental pollution: The case of Turkey," Renewable and Sustainable Energy Reviews, Elsevier, vol. 36(C), pages 180-187.
    26. Cerdeira Bento, João Paulo & Moutinho, Victor, 2016. "CO2 emissions, non-renewable and renewable electricity production, economic growth, and international trade in Italy," Renewable and Sustainable Energy Reviews, Elsevier, vol. 55(C), pages 142-155.
    27. Muhammad Shahbaz & Mete Feridun, 2012. "Electricity consumption and economic growth empirical evidence from Pakistan," Quality & Quantity: International Journal of Methodology, Springer, vol. 46(5), pages 1583-1599, August.
    28. Sahbi Farhani & Anissa Chaibi & Christophe Rault, 2014. "A study of CO2 emissions, output,energy consumption, and trade," Working Papers 2014-56, Department of Research, Ipag Business School.
    29. Bashiri Behmiri, Niaz & Pires Manso, José R., 2013. "How crude oil consumption impacts on economic growth of Sub-Saharan Africa?," Energy, Elsevier, vol. 54(C), pages 74-83.
    30. Shahbaz, Muhammad & Nasreen, Samia & Abbas, Faisal & Anis, Omri, 2015. "Does foreign direct investment impede environmental quality in high-, middle-, and low-income countries?," Energy Economics, Elsevier, vol. 51(C), pages 275-287.
    31. Pao, Hsiao-Tien & Tsai, Chung-Ming, 2011. "Modeling and forecasting the CO2 emissions, energy consumption, and economic growth in Brazil," Energy, Elsevier, vol. 36(5), pages 2450-2458.
    32. Ertugrul Yildirim & Alper Aslan & Ilhan Ozturk, 2014. "Energy Consumption And Gdp In Asean Countries: Bootstrap-Corrected Panel And Time Series Causality Tests," The Singapore Economic Review (SER), World Scientific Publishing Co. Pte. Ltd., vol. 59(02), pages 1-16.
    33. Omri, Anis, 2013. "CO2 emissions, energy consumption and economic growth nexus in MENA countries: Evidence from simultaneous equations models," Energy Economics, Elsevier, vol. 40(C), pages 657-664.
    34. Shahbaz, Muhammad & Khraief, Naceur & Uddin, Gazi Salah & Ozturk, Ilhan, 2014. "Environmental Kuznets curve in an open economy: A bounds testing and causality analysis for Tunisia," Renewable and Sustainable Energy Reviews, Elsevier, vol. 34(C), pages 325-336.
    35. Katircioğlu, Salih Turan, 2014. "Testing the tourism-induced EKC hypothesis: The case of Singapore," Economic Modelling, Elsevier, vol. 41(C), pages 383-391.
    36. Kaddour Hadri, 2000. "Testing for stationarity in heterogeneous panel data," Econometrics Journal, Royal Economic Society, vol. 3(2), pages 148-161.
    37. Cemal Atici, 2009. "Carbon emissions in Central and Eastern Europe: environmental Kuznets curve and implications for sustainable development," Sustainable Development, John Wiley & Sons, Ltd., vol. 17(3), pages 155-160.
    38. Emirmahmutoglu, Furkan & Kose, Nezir, 2011. "Testing for Granger causality in heterogeneous mixed panels," Economic Modelling, Elsevier, vol. 28(3), pages 870-876, May.
    39. Pesaran, M. Hashem & Smith, Ron, 1995. "Estimating long-run relationships from dynamic heterogeneous panels," Journal of Econometrics, Elsevier, vol. 68(1), pages 79-113, July.
    40. repec:asi:aeafrj:2012:p:518-529 is not listed on IDEAS
    41. M. Hashem Pesaran, 2007. "A simple panel unit root test in the presence of cross-section dependence," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 22(2), pages 265-312.
    42. Fuinhas, José Alberto & Marques, António Cardoso, 2012. "Energy consumption and economic growth nexus in Portugal, Italy, Greece, Spain and Turkey: An ARDL bounds test approach (1965–2009)," Energy Economics, Elsevier, vol. 34(2), pages 511-517.
    43. Ajmi, Ahdi Noomen & Hammoudeh, Shawkat & Nguyen, Duc Khuong & Sato, João Ricardo, 2015. "On the relationships between CO2 emissions, energy consumption and income: The importance of time variation," Energy Economics, Elsevier, vol. 49(C), pages 629-638.
    44. Peter Pedroni, 2001. "Purchasing Power Parity Tests In Cointegrated Panels," The Review of Economics and Statistics, MIT Press, vol. 83(4), pages 727-731, November.
    45. Ozturk, Ilhan & Aslan, Alper & Kalyoncu, Huseyin, 2010. "Energy consumption and economic growth relationship: Evidence from panel data for low and middle income countries," Energy Policy, Elsevier, vol. 38(8), pages 4422-4428, August.
    46. Apergis, Nicholas & Payne, James E., 2009. "CO2 emissions, energy usage, and output in Central America," Energy Policy, Elsevier, vol. 37(8), pages 3282-3286, August.
    47. Al-Mulali, Usama & Ozturk, Ilhan, 2016. "The investigation of environmental Kuznets curve hypothesis in the advanced economies: The role of energy prices," Renewable and Sustainable Energy Reviews, Elsevier, vol. 54(C), pages 1622-1631.
    48. Wolde-Rufael, Yemane, 2005. "Energy demand and economic growth: The African experience," Journal of Policy Modeling, Elsevier, vol. 27(8), pages 891-903, November.
    49. repec:ipg:wpaper:2014-582 is not listed on IDEAS
    50. Liddle, Brantley & Lung, Sidney, 2015. "Revisiting energy consumption and GDP causality: Importance of a priori hypothesis testing, disaggregated data, and heterogeneous panels," Applied Energy, Elsevier, vol. 142(C), pages 44-55.
    51. Tang, Chor Foon & Tan, Bee Wah, 2015. "The impact of energy consumption, income and foreign direct investment on carbon dioxide emissions in Vietnam," Energy, Elsevier, vol. 79(C), pages 447-454.
    52. Bölük, Gülden & Mert, Mehmet, 2015. "The renewable energy, growth and environmental Kuznets curve in Turkey: An ARDL approach," Renewable and Sustainable Energy Reviews, Elsevier, vol. 52(C), pages 587-595.
    53. Shahbaz, Muhammad & Mutascu, Mihai & Azim, Parvez, 2013. "Environmental Kuznets curve in Romania and the role of energy consumption," Renewable and Sustainable Energy Reviews, Elsevier, vol. 18(C), pages 165-173.
    54. Baek, Jungho & Pride, Dominique, 2014. "On the income–nuclear energy–CO2 emissions nexus revisited," Energy Economics, Elsevier, vol. 43(C), pages 6-10.
    55. Caraiani, Chirața & Lungu, Camelia I. & Dascălu, Cornelia, 2015. "Energy consumption and GDP causality: A three-step analysis for emerging European countries," Renewable and Sustainable Energy Reviews, Elsevier, vol. 44(C), pages 198-210.
    56. Katircioglu, Salih Turan & Feridun, Mete & Kilinc, Ceyhun, 2014. "Estimating tourism-induced energy consumption and CO2 emissions: The case of Cyprus," Renewable and Sustainable Energy Reviews, Elsevier, vol. 29(C), pages 634-640.
    57. Lee, Chien-Chiang & Chang, Chun-Ping, 2007. "Energy consumption and GDP revisited: A panel analysis of developed and developing countries," Energy Economics, Elsevier, vol. 29(6), pages 1206-1223, November.
    58. Zaman, Khalid & Shahbaz, Muhammad & Loganathan, Nanthakumar & Raza, Syed Ali, 2016. "Tourism development, energy consumption and Environmental Kuznets Curve: Trivariate analysis in the panel of developed and developing countries," Tourism Management, Elsevier, vol. 54(C), pages 275-283.
    59. Jahangir Alam, Mohammad & Ara Begum, Ismat & Buysse, Jeroen & Van Huylenbroeck, Guido, 2012. "Energy consumption, carbon emissions and economic growth nexus in Bangladesh: Cointegration and dynamic causality analysis," Energy Policy, Elsevier, vol. 45(C), pages 217-225.
    60. Harris, Richard D. F. & Tzavalis, Elias, 1999. "Inference for unit roots in dynamic panels where the time dimension is fixed," Journal of Econometrics, Elsevier, vol. 91(2), pages 201-226, August.
    61. Nasir, Muhammad & Ur Rehman, Faiz, 2011. "Environmental Kuznets Curve for carbon emissions in Pakistan: An empirical investigation," Energy Policy, Elsevier, vol. 39(3), pages 1857-1864, March.
    62. Shahbaz, Muhammad & Solarin, Sakiru Adebola & Mahmood, Haider & Arouri, Mohamed, 2013. "Does financial development reduce CO2 emissions in Malaysian economy? A time series analysis," Economic Modelling, Elsevier, vol. 35(C), pages 145-152.
    63. Kasman, Adnan & Duman, Yavuz Selman, 2015. "CO2 emissions, economic growth, energy consumption, trade and urbanization in new EU member and candidate countries: A panel data analysis," Economic Modelling, Elsevier, vol. 44(C), pages 97-103.
    64. Dogan, Eyup, 2015. "The relationship between economic growth and electricity consumption from renewable and non-renewable sources: A study of Turkey," Renewable and Sustainable Energy Reviews, Elsevier, vol. 52(C), pages 534-546.
    65. Levin, Andrew & Lin, Chien-Fu & James Chu, Chia-Shang, 2002. "Unit root tests in panel data: asymptotic and finite-sample properties," Journal of Econometrics, Elsevier, vol. 108(1), pages 1-24, May.
    66. repec:ipg:wpaper:2014-056 is not listed on IDEAS
    67. Seker, Fahri & Ertugrul, Hasan Murat & Cetin, Murat, 2015. "The impact of foreign direct investment on environmental quality: A bounds testing and causality analysis for Turkey," Renewable and Sustainable Energy Reviews, Elsevier, vol. 52(C), pages 347-356.
    68. Apergis, Nicholas & Payne, James E. & Menyah, Kojo & Wolde-Rufael, Yemane, 2010. "On the causal dynamics between emissions, nuclear energy, renewable energy, and economic growth," Ecological Economics, Elsevier, vol. 69(11), pages 2255-2260, September.
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