Environmental Kuznets Curve for CO2 in Canada Jie He∗

The environmental Kuznets curve hypothesis is a theory by which the re-lationship between per capita GDP and per capita pollutant emissions has an inverted U shape. This implies that, past a certain point, economic growth may actually be profitable for environmental quality. Most studies on this subject are based on estimating fully parametric quadratic or cubic regression models. While this is not technhically wrong, such an approach somewhat lacks flexi-bility since it may fail to detect the true shape of the relationship if it happens not to be of the specified form. We use semiparametric and flexible nonlinear parametric modelling methods in an attempt to provide more robust inferences. We find little evidence in favour of the environmental Kuznets curve hypothesis. Our main results could be interpreted as indicating that the oil shock of the 1970s has had an important impact on progress towards less polluting technology and production