Economic complexity and the inverted N-shaped EKC: Evidence from major nuclear energy economies

This study examines how economic complexity, nuclear energy, human capital, and military expenditure affect environmental sustainability in major nuclear energy–producing economies using panel data for 14 countries over 1995–2022. Employing a fixed-effects Driscoll–Kraay estimator, we find a robust inverted N-shaped Environmental Kuznets Curve (EKC) with respect to economic complexity: ecological footprint initially declines, temporarily rebounds at intermediate stages due to scale and rebound effects, and declines again at advanced levels as structural upgrading and cleaner energy systems enable renewed decoupling. Nuclear energy significantly reduces ecological footprint while human capital is associated with higher ecological pressure and military expenditure shows no robust effect. By replacing income-based measures with the Economic Complexity Index and focusing on nuclear-intensive economies, the study provides a mechanism-driven perspective on nonlinear environmental dynamics and yields stage-specific policy implications for clean energy deployment and environmental regulation.