Does urban sprawl lead to carbon emission growth? --Empirical evidence based on the perspective of local land transfer in China

The rapid expansion of urban areas has caused a series of impacts on the ecological environment. Exploring the effects of urban sprawl on carbon emissions and its mechanisms is crucial for realizing sustainable development patterns and low-carbon city planning. This study integrates used nighttime light data and population grid data to construct an Urban Sprawl Index. It employs a spatial Durbin model to analyze the spatial impact of urban sprawl on carbon emissions, examining the mechanisms from the perspective of local land transfers. The research reveals the following findings: (1) Urban sprawl significantly contributes to a positive spatial spillover effect on carbon emissions, leading to increased emission levels in surrounding cities. (2) The overall local impact of urban sprawl on urban areas is not significant. It suppresses carbon emissions in municipal districts but increases them in counties, with these effects counterbalancing each other. (3) Mechanism analysis indicates that different types of land transfers have varied effects on carbon emissions in districts and counties, and the regulation of the floor area ratio regulation strengthens the impact of land transfers. (4) Heterogeneity analysis shows that the size of urban populations significantly reduces the local effects of sprawl on carbon emissions, while environmental regulations strength attenuate the impact of urban sprawl on carbon emissions in municipal districts. The findings of this study provide practical references and policy implications for formulating reasonable urban development and land use plans, facilitating the achievement of peak carbon and carbon neutrality goals.