Abstract
Effective co-control of air pollution and carbon emissions yields substantial environmental and climate benefits, yet direct observational evidence of policy impacts remains scarce. Here we use tree-ring radiocarbon to reconstruct annual fossil fuel carbon dioxide concentrations from 2000 to 2021 in Beijing and Xi’an, China. These data, combined with records of fine particles, black carbon, and carbon monoxide, reveal their initial parallel rises, followed by substantial declines after 2013 clean air action plans. From 2013 to 2021, ratios of fine particles, black carbon, and carbon monoxide enhancement to fossil fuel carbon dioxide fell by 58 ± 25%, 54 ± 19%, and 44 ± 19% in Beijing, and 36 ± 21%, 56 ± 10%, and 65 ± 24% in Xi’an, respectively. These trends provide observational evidence of co-benefits achieved through integrated air quality and carbon mitigation policies, highlighting the value of tree-ring radiocarbon for evaluating emission dynamics and policy effectiveness.
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Data availability
All sources of publicly available data used in this study are provided in the Methods. The tree-ring 14C dataset (2000–2019) used for CO2ff reconstruction in Beijing and Xi’an was obtained from the same sampling network described in our previous work48. The present study includes additional 14C data from 2020 and 2021. Data used in the production of the figures in this study is stored in a repository with the following https://doi.org/10.5281/zenodo.18795196.
Code availability
The code for retrieving the satellite-derived PM2.5 data was provided by the data source website (https://sites.wustl.edu/acag/). Data visualization and linear fitting were conducted using standard tools in OriginPro 2021.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (grant Nos. 42330114 and 42173082), and Natural Science Basic Research Program of Shaanxi (grant number 2024JC-JCQN-34).
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Z.N. conceived the study; Y.H., G.Z., and X.F performed sampling and 14C sample preparation; X.L performed 14C measurements; Z.N., X.K., W.Z., S.W., and J.T. provided valuable discussions; Y.Q. and X.K. wrote the paper, which was revised by Z.N., X.K., W.Z., and J.T. All authors read and approved of the final manuscript.
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Qu, Y., Niu, Z., Zhou, W. et al. Synergistic reductions in fine particles and fossil fuel carbon dioxide revealed by tree-ring radiocarbon analysis. Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-03439-6
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DOI: https://doi.org/10.1038/s43247-026-03439-6
