CO2 emissions converge in China and G7 countries? Further evidence from Fourier quantile unit root test

G7 countries and China are considered not only the biggest energy producers globally but also the largest CO2 emission groups of countries among the world. In this study, we apply the Fourier quantile unit root test to investigate whether CO2 emissions converge in China and G7 countries using per capita CO2 emissions data over 1950-2013. While traditional unit root test results indicate that per capita CO2 emissions do not converge among these G7 countries and China, empirical results from the Fourier quantile unit root test point out that the CO2 emissions did converge in Germany, Italy, and the United Kingdom. Although the results of this study do not find strong CO2 emission convergence in the other five countries (i.e., Canada, France, Japan, the United States, and China), the CO2 emissions did converge in certain quantiles for these five countries. Our empirical results have important policy implications for the governments of G7 countries and China to implement the effective energy policy to reduce the CO2 emissions.