Even though standard growth models do not consider energy as an input for economic activities, energy is a basic factor of production in a modern economy (Rafiq and Salim 2009). Sadorsky (2009) denotes that energy consumption level is considered as a development indicator in the energy economics literature. Increases in economic activities and in industrialization and acceleration of urbanization result in increases in energy demand (Salim et al. 2008; Bilgili et al. 2016b). Hence, demand for energy sources rapidly increased in the last 50 years (Aslan et al. 2014). As British Petroleum (BP 2016) and World Bank (2016) exhibit, while the world primary energy demand grew by 17.7% from 2005 to 2013, the share of fossil energy sources, such as oil, natural gas and coal, in total primary energy demand was 81% in 2013. Put differently, the world counts on fossil energy sources, since most of the energy is produced through fossil energy sources (Salim et al. 2014). This dependence leads to major environmental problems, such as global warming, climate change and air pollution (Lau et al. 2012; Nejat et al. 2015; Kocak and Sarkgunesi 2017) because greenhouse gas emissions (GHGs), such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated gases, arise from the usage of fossil sources. With regard to the World Bank (2016) and US Environmental Protection Agency (EPA 2017) data, global GHGs almost doubled from 1970 to 2012, and CO2 had the greatest share in global GHGs with 76% in 2014. Therefore, CO2 emissions seem to be the main reason of the environmental problems, especially global warming and climate change (Wuebbles et al. 2002; Lau et al. 2012; Saboori and Sulaiman 2013; Nejat et al. ۲۰۱۵; Bilgili et al. 2017). CO2 intensity in the atmosphere has rapidly risen since the industrial revolution and has warmed the Earth (Maslin 2004; Narayan 2007; Swapnesh et al. 2014; Bilgili et al. 2017). One can observe that global CO2 emissions increased by 45% from 2000 to 2013 through the World Bank (2016) data. Since environmental pollution has become one of the largest global issues because of great increases in GHGs (Dogan and Seker 2016a), many meetings have been organized since 1970s in order to decrease environmental problems. The United Nations Conference on the Human Environment held in Stockholm in 1972, Rio de Janeiro Earth Summit in 1992, Kyoto Protocol shaped in 1997 and entered into force in 2005, and the 2015 United Nations Climate Change Conference in Paris were principal attempts to reduce environmental problems stemming from fossil energy sources.