The synergy between pollution reduction and carbon reduction in Chinese cities and its influencing factors

The synergy between pollution reduction (PR) and carbon reduction (CR) is crucial for cities facing both climate change and environmental pollution in achieving sustainable development. This study evaluates the PR-CR synergy in 295 Chinese cities from 2014 to 2022. Utilizing the improved Tapio Decoupling Principle and the Probit model, the study reveals that: (1) About 51.5% (152) of the cities demonstrated a synergy between PR and CR. This synergy varied across the years; for instance, 102 cities exhibited it in 2018 and 2020, but only 14 in 2019. (2) The remaining 48.5% (143 cities) did not exhibit this synergy, largely due to increased carbon emissions. These cities fall into three categories: those affected primarily by air pollution, carbon emissions, or both. (3) Environmental regulation emerged as the most influential factor promoting this synergy, with a significant coefficient of 81.47. Other positive influences included annual precipitation (0.000284), altitude (0.000650), Normalized Difference Vegetation Index (2.024), proportion of secondary industry (0.0168), proportion of construction land area (0.0182), and green patents (0.0000571). Conversely, average annual temperature (-0.0620) and relief amplitude (-0.0705) negatively impacted the synergy. This study enriches the discourse on PR-CR synergy, offering valuable insights for shaping sustainable development policies in cities.