RECENT PROGRESS IN ATMOSPHERIC FOSSIL FUEL CO2 TRENDS TRACED BY RADIOCARBON IN CHINA

ABSTRACT It is important to know how much of the increased atmospheric CO 2 is derived from fossil fuel emissions. Here, we review the progress in atmospheric fossil fuel CO 2 (CO 2 ff ) tracing over recent years by measurement of Δ 14 C in Chinese cities. In this paper we make progress by expanding the analysis from some locations to more regional views, by combining observations with modeling, and by making a preliminary comparison of observation-derived CO 2 ff with inventory-derived CO 2 ff . We have obtained a general picture of Chinese urban CO 2 ff and characteristics of its spatio-temporal variations at different scale, and identified the corresponding influencing factors. Interestingly, we found that the weekend effect of CO 2 ff was less evident in Chinese cities. In addition, we observed simultaneous variations in CO 2 ff and PM 2.5 in a winter haze event in Beijing and a simultaneous decrease in annual averages of CO 2 ff and PM 2.5 in Xi’an based on multi-year (2011–2016) Δ 14 CO 2 monitoring. We found that local coal combustion was the main source of CO 2 ff in Xi’an, which is located in the Guanzhong basin, by applying a WRF-Chem model and looking at δ 13 C signatures. Thus, reduction of coal consumption is a crucial target for carbon emissions reduction in China.