Land use carbon emission projections in shared socioeconomic and representative concentration pathways: Relationship with urbanization in Chinese megacities

Urbanization process significantly alters land use, thereby exacerbating the growth of carbon emissions and climate change-related risks. Understanding the changes in carbon emissions induced by urban land use changes can provide crucial information for developing effective policies for emission reductions. In this study, the change patterns of land use carbon emissions (LUCEs) were evaluated using land cover data and Energy Balance Tables (EBTs) in seven megacities in China in past two decades. Urban expansion projections under the Shared Socioeconomic Pathway (SSP) and Representative Concentration Pathway (RCP) scenarios were combined with the Constant Coefficient Riccati Grey model (CCRGM (1,1)) to predict forthcoming carbon emissions. LUCEs were projected from 2025 to 2040, and the average absolute percentage error of the CCRGM (1,1) was 0.19. The association between land urbanization and LUCEs was examined through the lens of the Environmental Kuznets Curve (EKC). Results indicate that future urban development policies should align with the SSP2-RCP4.5 scenario to effectively achieve carbon emission reduction targets. Beijing and Shenzhen reached their peak LUCEs in 2010, Shanghai and Tianjin in 2015, while Chongqing and Chengdu are expected to peak by 2030, and Guangzhou’s peak is projected to occur after 2030. The association between land urbanization and carbon emissions in Beijing, Chengdu, Shanghai, Shenzhen, and Tianjin follows an inverted U-shaped curve, while in Chongqing and Guangzhou, it forms an N-shaped curve. These findings provide valuable insights for cities facing similar challenges in promoting low-carbon development and formulating land use policies that integrate tenure security considerations.