Regional differences, dynamic evolution, and spatial spillover effects of carbon emission intensity in urban agglomerations.

Taking three major urban agglomerations in China as examples, this paper uses the Dagum Gini coefficient and its decomposition method, a Kernel density estimation method, and Markov chain and spatial Markov chain to study the regional differences, dynamic evolution characteristics, and spatial spillover effects of carbon emission intensity (CEI) of urban agglomerations, and accordingly, it proposes differentiated emission reduction and carbon reduction policies. The following results were obtained: (1) The overall CEI of the three major urban agglomerations and each individual urban agglomeration were found to have declined significantly over time, with an overall spatial pattern of "high in the north and low in the south," with inter-group differences being the main source of the overall differences. (2) The imbalance in CEI between cities was more obvious within the Beijing-Tianjin-Hebei (BTH) urban agglomeration, while the synergistic emission reduction effect of the Yangtze River Delta (YRD) and Pearl River Delta (PRD) urban agglomerations increased over the study period. (3) The probability of a city maintaining a stable level of CEI was much higher than the probability of a state shift, and there was a spatial spillover effect of carbon emissions between neighboring cities. This study can provide theoretical support for the global response to greenhouse gas emissions, promoting green development and carbon reduction in various countries and urban agglomerations and providing a quantitative basis for the formulation of relevant policies.