Decoupling relationship between urban land use morphology and carbon emissions: Evidence from the Yangtze River Delta Region, China

The increasing impact of urban land use and associated socio-economic activities on carbon emissions is evident. Clarifying the relationship between urban land use morphology (ULUM) and carbon emissions can help formulating policies for managing urban land use and reducing carbon emissions. However, research in this filed is still limited. Therefore, from the perspective of decoupling, this study focuses on the dynamic and economically robust Yangtze River Delta (YRD) region in China and explores the decoupling relationship between ULUM and carbon emissions during 1990 to 2020, with a particular emphasis on the decoupling relationship before and after urban land use transition (ULUT), based on ULUM assessment, carbon emissions estimation, and the decoupling model. The results showed that: (1) ULUM in the YRD region exhibited a fluctuating upward trend, with variations observed among different cities, and the year of ULUT in the YRD region was around 2003. (2) Overall carbon emissions in the YRD region exhibited an upward trajectory, with a noticeable slowdown in growth after 2005, when disparities in carbon emissions among cities began to widen progressively. (3) A dynamic decoupling relationship was observed between ULUM and carbon emissions, characterized primarily by negative decoupling. The proportion of cities experiencing negative decoupling increased to 100% from 1990 to 2010. During 2010-2020, this percentage gradually decreased, accompanied by a rise in cities experiencing decoupling. Regarding spatial distribution, negative decoupling shifted toward the central areas in the region, while decoupling gradually moved toward the northwestern and northeastern coastal areas in the region. Subsequently, this suggests that effective ULUT serves to mitigate carbon emissions, although the carbon reduction effect of ULUT has a certain time lag.