Revisiting the energy-growth-environment nexus in the OECD countries: An application of the CS-ARDL approach

Table 6 Results of the EKC hypothesis on CO₂ emissions

Variables	(1)	(2)	(3)	(4)	(5)	(6)	(7)
	lnCO₂	lnCO₂	lnCO₂	lnCO₂	lnCO₂	lnCO₂	lnCO₂
lnY	2.758	− 1.290	− 6.441	3.86**	− 1.602	2.839	− 5.088
	(2.790)	(4.112)	(6.005)	(1.912)	(2.928)	(5.965)	(5.002)
lnY²	− 13.188	2.864	31.233	− 19.06**	8.267	− 13.430	23.925
	(13.958)	(21.701)	(28.515)	(9.543)	(13.852)	(28.576)	(23.618)
lnRE	x	x	x	x	x	x	x
lnNRE	x	x	x	x	x	x	x
lnTRD	x	x			x	x
lnFD	x		x		x		x
lnURB	x			x		x	x
Observations	848	848	848	848	848	848	848
R-squared	0.234	0.333	0.342	0.341	0.285	0.271	0.302
Number of groups	37	37	37	37	37	37	37

** and * significant at 5% and 10%, respectively. We use CS-ARDL(1,0,0,0,0,0,0,0). The independent variable is carbon dioxide, and the independent variables include income (Y), its squared term (Y²), renewable energy (RE), nonrenewable energy (NRE), trade openness (TRD), financial development (FD), and urbanization (URB). Standard errors are in parentheses. “x” represents the inclusion of variables in the regression

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