Confronting the Environmental Kuznets Curve

T he environmental Kuznets curve posits an inverted-U relationship between pollution and economic development. Kuznets’s name was apparently attached to the curve by Grossman and Krueger (1993), who noted its resemblance to Kuznets’s inverted-U relationship between income inequality and development. In the first stage of industrialization, pollution in the environmental Kuznets curve world grows rapidly because people are more interested in jobs and income than clean air and water, communities are too poor to pay for abatement, and environmental regulation is correspondingly weak. The balance shifts as income rises. Leading industrial sectors become cleaner, people value the environment more highly, and regulatory institutions become more effective. Along the curve, pollution levels off in the middle-income range and then falls toward pre-industrial levels in wealthy societies. The environmental Kuznets curve model has elicited conflicting reactions from researchers and policymakers. Applied econometricians have generally accepted the basic tenets of the model and focused on measuring its parameters. Their regressions, typically fitted to cross-sectional observations across countries or regions, suggest that air and water pollution increase with development until per capita income reaches a range of $5000 to $8000. When income rises beyond that level, pollution starts to decline, as shown in the “conventional EKC” line in Figure 1. In developing countries, some policymakers have interpreted such results as conveying a message about priorities: Grow first, then clean up. Numerous critics have challenged the conventional environmental Kuznets curve, both as a representation of what actually happens in the development process and as a policy prescription. Some pessimistic critics argue that crosssectional evidence for the environmental Kuznets curve is nothing more than a