How do land supply admittance regulations affect urban carbon emissions?

The rationalization of land resource utilization, affected by increasing stringent guidance of urban land supply regulations, is a vital path for countries to achieve their sustainable development goals. However, evidence on environmental effects of land supply regulations is scarce. Thus, adopting China's land supply policy, we investigate the impact of land supply admittance regulations (LSARs) on urban carbon emissions (UCEs) by using the land market transaction data and carbon emission data of China's 285 cities from 2007 to 2019. The result shows that LSARs notably curb UCEs, with UCEs decreasing by 0.051 standard units (approximately 1.052 g CO₂ per RMB) for each 1 standard unit increase in LSARs. After introducing the instrumental variable to deal with endogenous issues, this conclusion remains robust. Mechanism analysis indicates that the carbon abatement effect of LSARs is through structural and efficiency two main channels: the industrial structure advancement from quantity and quality; the green production efficiency from scale and technology. Furthermore, heterogeneity results demonstrate that the reduction effect varies in admittance regulations setting, government intervention, land supply marketization, and environmental regulations. Our findings provide valuable insights for other economies seeking to adopt land-based policy instruments for carbon governance and urban sustainability.