Heterogeneous environmental regulations and carbon emission efficiency in China: A perspective of resource endowment

China, as the world's largest carbon emitter, is striving for green transformation through the implementation of various environmental policies. This study employs panel data from 30 Chinese provinces between 2000 and 2022 to analyze in-depth the heterogeneous effects of three types of environmental regulations. The findings reveal a U-shaped relationship between both general public environmental regulation (GER) and mandatory environmental regulation (MER) and carbon emission efficiency (CEE). Conversely, stimulating environmental regulations (SERs) exhibit an inverted U-shaped relationship with CEE. Mechanism analysis further reveals that environmental regulations enhance CEE by promoting industrial structural upgrades and technological innovation. Notably, SERs are particularly effective in improving the CEE in resource-rich and moderately resourced provinces. However, GER exhibits a masking effect on the pathway of technological innovation, indicating potential inefficiencies in its implementation. Moreover, heterogeneity analysis demonstrates that mandatory environmental regulation has a more pronounced impact on improving the CEE in resource-rich and moderately resourced provinces, whereas this impact is relatively weaker in resource-poor provinces. This finding underscores the importance of tailoring environmental policies to the specific resource characteristics of different regions. The insights from this study offer critical guidance for policymakers in designing and implementing differentiated environmental regulation policies, particularly in advancing China's transition toward a sustainable, green, and low-carbon future.