Evaluation of the synergistic emission reduction benefits of pollution and carbon reduction and regional synergy network analysis in Chinese cities

Achieving synergy in pollution reduction and carbon emission reduction is a pivotal approach to advancing green transformation and driving high-quality low-carbon development. This research assesses the synergistic benefits of pollution and carbon emission reduction and analyzes the regional synergistic network among 279 Chinese cities from 2005 to 2020. Using the marginal emission reduction cost method, the synergistic benefits of PM2.5 and CO2 reduction are quantified, while the temporal exponential random graph model is employed to analyze the dynamic evolution and driving factors of the synergistic network. Key findings include: (1) At the national level, synergistic strategies reduce marginal emission reduction costs, with benefits exceeding 45 %, achieving economic and environmental win-win outcomes. (2) Compared to separate reduction, synergistic strategies significantly lower costs, with final growth rates of 70.11 % for carbon reduction and 61.26 % for pollution reduction, far below 102 % and 99.23 % in separate reduction. (3) Significant regional differences exist, with cities in the Yangtze River Economic Belt and central region demonstrating stronger synergistic benefits. (4) Core nodes like Beijing and Shanghai enhance regional benefits through information and resource dissemination. The research highlights the role of synergistic reduction in optimizing resource allocation and reducing costs, offering scientific support for cross-regional governance and policy optimization.