From curve to surface: Unraveling nonlinear dynamics in the resource–environment–economy nexus

Understanding the nonlinear interactions among resource use, environmental pressure, and economic growth is fundamental to advancing sustainable development. However, the role of resources in shaping these dynamics remains unclear. To address this gap, this study extends the classical two-dimensional Environmental Kuznets Curve (EKC) framework by introducing resource as a third dimension, proposing a Resource–Environmental Kuznets Surface (REKS) model to capture the complex interplay within resource–environment–economy (REE) systems. Using an entropy-based evaluation framework and applying a multilayer perceptron (MLP) neural network, we simulate the REKS across 15 representative countries, including the G7, BRICS, and Least Developed Countries (LDCs), from 2000 to 2020. The results reveal a parabolic pattern of REE dynamics across all countries, with substantial spatial heterogeneity and nonlinear dynamics observed among different country groups. BRICS and LDCs remain locked in low-coordination equilibria, while G7 countries exhibit differentiated, higher-sustainability trajectories. Critically, resource emerges as a decisive factor, advancing the onset of economic–environmental turning points, reshaping systemic trajectories, and lowering the threshold for environmental improvement as resource consumption intensifies. Furthermore, reducing resource consumption exerts a stronger impact on environmental improvement than does economic development. These findings provide empirical evidence for multi-threshold behaviors in REE systems and provide new insights into sustainability transitions, helping to guide targeted policy measures for resource governance across diverse national contexts.