The Environmental Kuznets Curve reconsidered: Assessing direct and indirect energy use in global grain supply chains

Previous production-based EKC studies in agriculture have largely ignored trade-embodied energy and indirect upstream burdens, risking misinterpretation of domestic decoupling as genuine progress rather than displacement. This study examines energy use in global grain supply chains across 39 countries from 1995 to 2021, using a multi-regional input–output (MRIO) framework to estimate direct on-farm and indirect upstream energy consumption—including energy embodied in imported grain—and method-of-moments quantile regression to capture distributional heterogeneity. Key findings include: (1) no inverted U-shaped EKC for direct energy use across any quantile, with intensity rising monotonically with income; (2) EKC-like patterns for indirect and total energy, but only in higher quantiles (Q6–Q9), suggesting selective decoupling in high-energy-consumption (typically high-income) countries via technological and structural change; and (3) a strong positive effect of calorie intake on energy use across all models, while renewable energy share and agricultural R&D show unexpected positive associations with indirect/total energy in upper quantiles, indicating rebound and supply-chain expansion effects. These results demonstrate that income growth and cleaner energy alone are insufficient for sustainable food systems. Policy priorities include: targeted on-farm regulations to break direct energy lock-in in middle-income countries; lifecycle and trade-aware instruments (e.g., carbon border adjustments) to address indirect energy leakage; demand-side measures to moderate calorie-driven pressure; and rebound-mitigating designs for renewable energy and R&D policies. Integrated reforms balancing production efficiency, consumption patterns, and global trade governance are urgently needed, particularly in low- and middle-income countries where food-system energy demand is accelerating rapidly.