Is the environmental Kuznets curve hypothesis valid? A global analysis for carbon dioxide emissions

Environmental Kuznets curve (EKC) hypothesis was first introduced in the early 1990s, and during the last three decades, many researchers have been interested in EKC hypothesis since it is creating hope for achieving environmental sustainability without reducing economic growth. On the other hand, there are many opponents of the EKC hypothesis and there is no agreement on the hypothesis's validity. This study aims at contributing to the debate on the validity of the EKC hypothesis by analyzing the CO2 emissions of all the countries in the world that have carbon dioxide (CO2) emissions per capita over 1 Mt and a population over 10 million. Instead of panel data analysis, we preferred to use a time-series analysis of individual countries with annual data for the 1970-2019 period and supported the econometric analysis with a graphical analysis. We used ordinary least squares as an estimation method. According to our results, the EKC hypothesis is not strong enough to be generalized for every economy or a group of economies. Although the EKC hypothesis is relevant for some high-income countries, there are a considerable number of rich and polluting economies that don't support the EKC hypothesis. Since EKC hypothesis is not valid at a global scale, regardless of the level of income, all countries need to seek better ways of limiting CO2 emissions.