Fig. 3. Regional patterns of CO₂ emission reduction co-benefits in 2020.

a–d CO₂ emission reduction from six measures in Beijing–Tianjin–Hebei region (BTH), Yangtze River Delta region (YRD), Pearl River Delta region (PRD), and Fenwei Plain region (FW), respectively. e The provincial CO₂ emission reduction in 2020. f The relationship between the policy effectiveness, air quality improvement, and CO₂ emission reduction. Each bubble in f indicates a province, with the size representing the CO₂ emission reduction in 2020 and the color representing the proportion of CO₂ emission reduction to real local CO₂ emissions in 2020. The policy effectiveness provides a general measure of the policy intensity in a region, with the coefficient value ranging from 0 (very weak) to 1 (very strong), and more details are presented in Supplementary Note 1 and Supplementary Tables 2 and 3.