Progress, trade-offs, and synergies of sustainable development goals in China’s urban agglomerations

Abstract Under the framework of the global Sustainable Development Goals (SDGs), quantifying SDG progress and examining the inter-goal interactions in China’s urban agglomerations provides an important scientific basis for differentiated regional sustainability strategies and the optimization of synergistic development pathways. This study investigates 19 urban agglomerations and selects 11 SDGs to construct an evaluation index system tailored to the Chinese context. Using six time-slice datasets (2012, 2014, 2016, 2018, 2020 and 2022), the entropy weighting method, COCOSO, and TOPSIS models are employed to measure composite performance, absolute progress, and relative proximity toward SDG attainment, while Spearman correlation analysis is further applied to identify synergies and trade-offs among goals. The results show that progress in key SDGs across China’s urban agglomerations displays pronounced spatial heterogeneity, generally declining from eastern coastal areas to central, southwestern, and northwestern areas regions. Coastal agglomerations such as the Pearl River Delta and Yangtze River Delta exhibit relatively high development levels, whereas several central and western agglomerations lag, including the Beibu Gulf urban agglomeration. Absolute progress reveals steady improvements in most SDGs over time, although SDG3, SDG6, and SDG16 experiences fluctuations or temporary declines, while relative proximity highlights persistent disparities among goals, with SDG12 showing consistently high stability and proximity and SDG9, SDG3, and SDG15 demonstrating more volatile trajectories. Inter-goal relationships comprise nine strong synergies, eight weak synergies, and one weak trade-off. Over the study period, synergistic relationships have expanded, although conflicts between certain goal pairs remain prominent. Overall, the findings underscore the need to address regional disparities by integrating absolute progress and relative proximity and by harnessing synergies among SDGs to promote coordinated development, thereby strengthen sustainable development capacity of China’s urban agglomerations.