Income inequality and the environment: Aggregation bias in environmental Kuznets curves

The environmental Kuznets curve assumes an inverted U-shaped relation between environmental damage and per capita income. Recently it has been argued in the literature that in addition to income levels, the inequality in the distribution of power and income is (positively) related to environmental degradation. We provide an additional argument, based on simple aggregation, for including a measure of income dispersion in empirical analyses. When the relationship between environmental damage and household income is concave (e.g. resembles an environmental Kuznets curve), then income inequality is negatively related to total environmental damage. Results from an empirical analysis of cross-national variation indicate that the aggregation effect can run counter to and outweigh the political economy effect for some environmental indicators.