National aspirations but local realities? Regulatory stringency and policy drivers of local carbon peak in China

China’s 2030 carbon peak pledge is a central component of its climate policy, which is crucial for its 2060 carbon neutrality goal and global efforts to meet the 1.5°C climate target. While the primary responsibility for achieving this national ambition falls to local governments, the stringency of their policies varies widely. To explain this variation, this study constructs a novel 4A index–Attitude, Ambition, Action, and Accountability–to measure regulatory stringency of local carbon peak policies. Our analysis revealed that stringent policies are characterized by three core elements: specific and measurable indicators, comprehensive sectoral coverage, and clearly designated responsible actors. Employing the index scores, we divided local governments into very weak, weak, medium, and strong policy categories. Within a four-factor explanatory framework, we identified key drivers for different levels of policy stringency. The results showed that local governments facing weak to medium political pressure tend to adopt more stringent policies, suggesting that strong top-down pressure may foster symbolic rather than substantive compliance. Furthermore, a locality’s existing renewable energy mix is a significant predictor of policy stringency. This research provides a new theoretical and empirical metric for assessing climate governance and offers critical insights for policymakers to improve local climate policies.