From conflict to coordination: A new framework to measure the synergy level of pollution-carbon-growth

This paper proposes a new framework for measuring the synergy degree of pollution reduction and carbon mitigation, using the optimal direction as the benchmark and the proximity between the actual direction and this benchmark as the principle for synergy degree measurement. This measurement framework considers both the actual and optimal directions, quantifies the degree of proximity through the cosine function, and thus intuitively presents the synergy level, effectively addressing the limitation of existing research that predominantly focuses on the actual direction alone. Additionally, it offers differentiated synergy directions based on the actual development stages of different regions. Based on this framework, the paper explores the overall characteristics, evolving trends, and influencing factors of the synergy level of pollution and carbon reduction in China's cities. The results show that the synergy level of pollution and carbon reduction exhibits a fluctuating upward trend, and reducing carbon intensity should be the main focus for improving the synergy level. The synergy levels in the eastern, central, and western regions are relatively lower during their respective periods of rapid economic growth. By employing a simple empirical model to analyze the influencing factors, this paper finds that enhancing economic development levels, promoting green technology innovation, and increasing government attention to ecological environment protection are effective measures to improve the synergy level of pollution and carbon reduction. Conversely, an excessively high proportion of secondary industry and higher economic growth targets will adversely affect the synergy level.