Bridging Effect–Efficiency Gaps in Low-Carbon Resilient Cities: Evidence on Synergistic Development and Nonlinear Drivers from Chinese Cities

Advancing the low-carbon and resilient transformation of urban systems has become a crucial strategy for addressing the climate crisis. Current research predominantly focuses on either the effect of governance or the efficient utilization of urban systems, overlooking the potential structural mismatches and synergistic development governance logic between the two. This paper systematically proposes a theoretical research framework integrating the synergistic development of urban system effect and efficiency, and constructs a multi-level analytical methodology. Through an in-depth examination of 278 prefecture-level cities in China from 2010 to 2023, the following key conclusions emerge: (1) The overall level of synergistic development within urban systems has steadily increased. Specifically, the proportion of cities at low levels of synergistic development decreased from 65.11% to 17.63%, while the proportion at medium and high levels rose from 18.70% to 46.40%. (2) Spatial disparities in urban system coordination have progressively narrowed, as evidenced by the overall Gini coefficient decreasing from 0.195 to 0.153. (3) Key influencing factors for urban system coordination include foreign enterprise attraction, urban infrastructure development, and green technological innovation. Overall, this study reveals the long-standing structural mismatch between effect and efficiency in China’s urban system’s low-carbon resilience transformation, emphasizing the importance of their coordinated development. It provides theoretical foundations and empirical references for the sustainable development of urban low-carbon resilience transformation.