Coupled coordination study of inter-provincial carbon emission efficiency and ecological infrastructure in China

Understanding the coupling relationship between ecological infrastructure (EI) and carbon emission efficiency (CEE) is critical for China to achieve its 2030 carbon peak target. This study develops a comprehensive evaluation index system to assess inter-provincial EI development and employs the Non-Radial Directional Distance Function (NDDF) method to quantify provincial-level CEE. Subsequently, the coupling coordination degree (CCD) between EI and CEE from 2004 to 2022 is calculated using a coupling coordination model. Based on these findings, the development trend of the CCD for the period 2023-2030 is projected using the Grey Prediction GM(1,1) model. The results indicate that both EI and CEE have exhibited steady improvements between 2004 and 2022, albeit with significant regional disparities. The eastern region demonstrates the highest levels of CEE, while the western region surpasses others in EI development. The CCD between EI and CEE has increased consistently over time, revealing distinct spatial autocorrelation and clustering effects. Notably, regions characterized by low CCD (Cold spots) have decreased, whereas those with high CCD (Hot spots) have become more pronounced, although no continuous geographical pattern has emerged. Projections for 2023-2030 suggest that maintaining the current trajectory will lead to slower progress. However, targeted policies could substantially enhance CCD and mitigate regional disparities. This study provides valuable insights into the dynamic interaction between ecological infrastructure and carbon efficiency, offering strategic implications for promoting regional sustainable development, advancing environmental justice, and enhancing long-term climate resilience.