Regional effect as a probe of atmospheric carbon dioxide reduction in southern China.

To mitigate climate change, China is striving to reduce its carbon dioxide (CO 2) emissions before 2030 and has derived a series of national environmental policies to advocate green development. Analysing the changes in regional atmospheric CO 2 concentrations could be more convincing in evaluating the impact of the associated strategies. In this study, a three-year continuous observation campaign of the atmospheric CO 2 mole fraction was first conducted at the summit of the Nanling Mountains, southern China in 2015–2017 to probe the timely feedback of the implementation of the green policies of the government. The effects of regional emissions and removals on the CO 2 mole fraction were subsequently analysed to explore the primary processes and regional contributions driving the background CO 2 concentration. Approximately 86.4% of the observed values were filtered as background events, with average CO 2 concentrations of 395.9 ± 6.8 ppm. The curve-fitting CO 2 mole fraction showed a slight short-term descending trend (0.6–2.2 p.m. y−1) that was rarely seen against the backdrop of a continuous rise of the global average over the years. In addition to the possible impacts of the changes in regional-scale CO 2 sources and sinks, we inferred that the vigorously enforced sustainable development policies of the Chinese government should be accentuated to reduce CO 2 emissions. Although the conclusion relies heavily on a relatively short dataset, this study may globally help the people to reduce carbon emissions. [Display omitted] • Systemic measurement of atmospheric CO 2 concentration in southern China. • Monitored a low background CO 2 concentration below global and China's average. • Reported a rare regional descending event of atmospheric CO 2 concentration. • Verified the feasibility of the 2030 peak CO 2 emission targets for China. • Emphasized the contribution of green development policies to CO 2 reduction. [ABSTRACT FROM AUTHOR]