The Environmental Kuznets Curve and Flow versus Stock Pollution: The Neglect of Future Damages

In this paper we offer a possible explanation for the empirical finding that the pollution-income relationship (PIR) for flow pollutants is an environmental Kuznets curve (EKC), i.e. inverted-U shaped, but that the PIR for stock pollutants is monotonically rising. We analyse an overlapping generations model with two pollutants: The flow pollutant causes immediate damages, but the stock pollutant harms the environment only in the future. Hence, a succession of myopic governments lets stock pollution grow with income. In contrast, the flow pollutant follows an EKC whose downturn might be caused by the neglect of future damages and by ever rising stock pollution: Without the stock pollutant the PIR for the flow pollutant can increase monotonically. We also show that the turning point of the EKC for the flow pollutant lies at lower levels of income and of flow pollution if stock pollution is high and harmful. This casts doubts on most empirical EKC studies because they assume that the turning point occurs at the same income level in all countries. However, it is consistent with recent empirical findings that the income level at the turning point of the EKC varies across countries.