Regional integration can significantly affect carbon emissions, but scholars have paid more attention to the impact of integration level, ignoring the importance of regional integration expansion. This study attempts to demonstrate whether, in the process of promoting carbon peak and carbon neutrality in China, the transformation of the administrative region’s economy into an integrated economy based on urban agglomeration regional integration expansion affects urban carbon emissions. This study considers the regional integration expansion of the Yangtze River Delta Urban Economic Coordination Committee as a quasi-natural experiment, exploring the carbon emission reduction effect of regional integration with the difference-in-differences model. With the mediating and moderating effect models, this study examines the mechanism of regional integration affecting urban carbon emissions. The results show that regional integration, considering regional integration expansion, can significantly reduce urban carbon emissions. The carbon emission reduction effects of regional integration show significant heterogeneity. For example, there is a significant carbon emission reduction effect of high-hierarchy cities and an insignificant carbon emission reduction effect of general-hierarchy cities. Further research into the driving mechanism finds that deepening collaborative governance, industrial structure optimization, and green technology promotion brought about by regional integration are important mechanisms influencing urban carbon emissions. In addition, the carbon emission reduction effect of regional integration is influenced by the level of urban marketization and development efficiency. Different from the existing studies focusing on the effects of regional integration level, this study assesses the feasibility of promoting urban green development through urban agglomeration regional integration expansion. Based on the relevant empirical research, we propose to better promote high-quality development by strengthening urban agglomeration cooperation, optimizing urban development paths, strengthening innovative development, and improving macro political systems. It also indicates that the relevant policies should be formulated after considering local conditions.

Innovation is an important factor to improve the quality of economic growth, and amplifying the innovation spatial spillover effect is an important measure to support the development of innovation. Scholars have carried out diversified research on the innovation spatial spillover effect, but there is still practical significance for deepening the research on the spatial spillover effect. In particular, the multi-angle comparative study in different regions still has research value, especially for the field of urban agglomeration integration. The spatial econometric model is a common method to measure spatial spillover effect. In order to carry out a multi-angle comparative study of innovation spatial spillover effects in different regions, this study takes two typical integrated urban agglomerations of the Yangtze River Delta and the Pearl River Delta in China as the object, and conducts a comparative study of the evolutionary characteristics of innovation spatial spillover effects based on urban scale data and the spatial econometric model. Differently from previous studies, invention patents are adopted to characterize the innovation level. The results show that there are significant positive innovation spatial spillover effects in the Yangtze River Delta and the Pearl River Delta, and the spatial spillover effect in the Yangtze River Delta is stronger. The spatial spillover effect exhibits significant spatiotemporal heterogeneity. For example, the spatial spillover effect in the core region and the fringe region of the urban agglomeration exhibits a positive effect, but the Yangtze River Delta is stronger than the Pearl River Delta. As an important innovation, the spatial spillover effects both exhibit the evolutionary characteristics of “inverted U-shape” based on the changes in geographical distance, and the spatial spillover effect of the Yangtze River Delta is always larger. Based on the empirical research, we propose promoting high-quality development by strengthening urban agglomeration cooperation, realizing urban agglomeration expansion in an orderly way, and improving the macro-political system.

The differences in innovation, and the resulting inefficient allocation of innovation resources, are key factors affecting the high-quality development of urban agglomerations. In the context of China’s upgrading of the integrated development of the Yangtze River Delta (YRD) to a national strategy, the study of innovation patterns and driving factors in this highly developed urban agglomeration provide references and experiences for high-quality development and innovation improvements in other urban agglomerations. Using prefecture-level patent data from 2000 to 2018, this study analyses the evolution characteristics of the innovation patterns in the YRD, from the perspective of innovation level and innovation growth, based on the coefficient of variation, locational Gini coefficient, and the relative development rate index. Then, using the knowledge production function, this study quantitatively explores the driving factors for innovation from multiple perspectives. The main findings are as follows. The differences in urban innovation levels decrease with improvements in the innovation level of urban agglomerations. In terms of the evolution of the spatial pattern of innovation levels, the “core–periphery” and “south–north” differences are highly stable; however, the innovation levels of some peripherical cities improve. The growth of urban innovation levels show significant regional differences, with fast-growing cities clustered in the core area, and high-value areas characterized by proximity diffusion. Based on the innovation level in different periods, cities are divided into low–low, low–high, high–low, and high–high types. There are spatio–temporal differences in the driving factors for innovation. On the one hand, different periods show an intensification of factor inputs and external linkage effects, as well as the differentiation of urban development state effects. On the other hand, there are differences among different types of cities, with low–low cities mainly driven by factor inputs, urban development state, and internal opening-up; low–high and high–high cities are greatly influenced by factor inputs and urban development state. By expanding on existing studies, the present research provides a refined reference for the formulation of scientific policies aimed at promoting innovation development in China.

In the face of carbon emissions reduction efforts, which are a common but differentiated global responsibility, it is crucial to explore the potential synergistic path between economic growth and carbon emissions reduction. This study integrates economic growth management and carbon emissions into a theoretical framework, based on city-level panel data from 2005 to 2019 in the Yangtze River Delta and the fixed effects model. We explore the impact of economic growth targets on urban carbon emissions. Then, we explore the mechanism by which economic growth target affects carbon emissions with the mediation effect model and moderation effect model. The results reveal that economic growth targets are beneficial for carbon reduction, and innovation development from innovation transformation is an important mechanism driving carbon emissions reduction, but the effects of different innovation outputs exhibit notable variations. In addition, marketization and industrial structure affect the relationship between economic growth targets and carbon emissions. The heterogeneity analysis reveals substantial spatial and temporal differences. Based on the realities of developing countries’ ongoing economic targets, this study provides a new explanation for the relationship between government policies and carbon emissions, establishing a scientific basis for policymakers to formulate strategic green development policies.

This paper investigates the spatial mechanisms and impacts of land transfer on green total factor productivity (GTFP) in the economically dynamic Yangtze River Delta region of China. Using urban-level panel data from 2007 to 2020 and applying spatial econometric models, the study examines the relationship between land transfer and GTFP. The results of the spatial econometric analysis show that land transfer in the overall Yangtze River Delta region contributes positively to the improvement of GTFP. The mediating mechanism of industrial restructuring and upgrading shows statistically significant effects. Further investigation reveals differences in the spatial interdependence of land transfer on the GTFP among cities in different regions. Land transfer in the core area has significant indirect effects on the GTFP of neighboring cities, while the impact of land transfer in peripheral cities on the GTFP of surrounding cities is less discernible. This suggests that there is still a need for further deepening and development of integration in peripheral cities, as factor integration is still insufficient. The findings of this study provide useful insights for local governments in optimizing land transfer practices and promoting industrial transformation, upgrading, and sustainable green development.

The urban–rural income gap remains a central issue in the income distribution of developing countries, constraining regional coordination and social equity. Although stable economic development is essential for narrowing this gap, the distributional consequences of local economic growth management have received insufficient attention, especially from the perspective of urban spatial structure. Drawing on the urban bias theory and spatial economics, this study uses panel data from 41 prefecture-level cities in the Yangtze River Delta region of China during 2007–2023 and applies a two-way fixed effects model to examine the effect of economic growth target pressure on the urban–rural income gap and the mediating role of urban spatial structure. The results show that economic growth target pressure significantly widens the urban–rural income gap, with an estimated increase of approximately 0.001–0.002 units in the Theil index. Mediation analysis further indicates that target pressure promotes a more monocentric urban spatial structure, which partially mediates the effect. The results also show evident temporal and regional heterogeneity. These findings suggest that growth-oriented local governance may reshape income distribution through spatial organization, offering empirical evidence for optimizing local economic management and urban spatial structure to promote coordinated urban–rural development.