How does public transport development contribute to carbon emission reduction?

• The development of public transport can reduce carbon emissions. • The public transport ridership attraction shows a partial mediation effect. • The private car ownership ratio demonstrates a suppression effect. • Recommendations for the development of public transport are proposed. As an essential service to ensure residents’ green travel, the development of public transport represents a substantial avenue to achieving the dual-carbon strategic goals. Under the policy background of public transport promotion, we use the data samples from 30 provincial-level regions in China from 2004 to 2019 to empirically analyze public transport development’s carbon emission reduction effect and its mechanism. The results show that increasing the line length and vehicles of public transport can significantly reduce carbon emissions. Both public transport ridership attraction and private car ownership ratio serve as mediators in the relationship between public transport development and carbon emission reduction. The key difference is that public transport ridership attraction shows a partial mediation effect, while private car ownership ratio demonstrates a suppression effect. These findings have important policy implications for the effective integration between the dual-carbon strategic goal and public transport promotion policy, while also providing effective guidance for the practical development of public transport.