Resolving conflicting findings on low-carbon city pilots: stage-specific impacts and the role of voluntary vs. mandatory policies in emissions reduction

Although China’s Low-Carbon City Pilot (LCCP) policy has been extensively studied, its precise impact on carbon emissions remains contested. Some studies report substantial reductions in emissions and intensity, while others find limited or no effects. A key reason for these discrepancies is the failure to distinguish between the policy’s three distinct implementation phases. Launched in 2010, 2013, and 2017, each batch of pilot cities adopted increasingly stringent regulatory approaches, shifting from voluntary initiatives to mandatory enforcement. The failure to account for these differences in policy design leads aggregate analyses to obscure critical variations in outcomes, thereby limiting the ability to determine the effectiveness of specific measures across varying contexts. Addressing this gap helps clarify ongoing theoretical debates in climate governance and can inform more effective, locally tailored policy design in China and other emerging economies. This study addresses that gap by separately evaluating the three LCCP batches (2010–2013, 2014–2016, 2017–2021) using a multi-period Difference-in-Differences (DID) framework. Key findings indicate that: (1) Mandatory measures in the third batch significantly reduced CO₂ intensity by 0.168 tons/10,000 CNY in pilot cities, contrasting with earlier voluntary phases showing statistically insignificant effects; (2) Emission reductions from mandatory measures appear to stem primarily from government supervision and technological innovation, with limited impact on individual green travel behavior; (3) Voluntary measures reduced per capita CO₂ emissions by 5.669 tons in high-income regions but increased emissions in low-income areas, highlighting context-dependent efficacy. Based on city-level data from China, these findings offer lessons for emerging economies: mandatory policies are crucial for rapid industrial emission reductions, while voluntary measures are more effective in high-income, tech-intensive regions. Long-term success depends on integrated strategies that align top-down regulation with grassroots participation. By showing that stage-specific evaluation and the strategic sequencing of voluntary and mandatory measures can significantly enhance decarbonization outcomes, this study contributes to ongoing theoretical discussions and provides empirical insights for policy practice.