Greater economic inequalities increase environmental degradation in most cases. Building on evidence from 136 studies and 406 empirical tests between 1998 and 2022, we construct a database enabling an in-depth analysis of the literature. Our main findings are threefold. First, high levels of inequality lead to high levels of regional and local environmental pressure, whereas they have mixed effects on climate change. Furthermore, greater inequalities weaken environmental responses, including public policies. Second, empirical analyses are increasingly focusing on climate change, employing diverse methods and inequality indicators and broadening the countries studied. However, developing countries are less well investigated. Third, theoretical transmission channels remain fairly untested, while new empirical results are not accounted for in theoretical frameworks. The development of new empirical strategies to identify the dominant channels through which inequalities constitute an obstacle to the ecological transition is now essential.
