Stochastic and club convergence of ecological footprint: An empirical analysis for different income group of countries. The convergence of environmental pollution is one of the contemporary issues in economics. Indeed, most of the long-run climate projections and future predictions of environmental conditions are based on convergence presumption. The pioneer studies initially focused on the convergence of carbon emission per capita, yet convergence of ecological footprint per capita, accepted as a more comprehensive environmental degradation indicator than carbon emission per capita, has been begun to examine by researchers as well.