Ongoing CO2 monitoring verify CO2 emissions and sinks in China during 2018–2021

Accurate estimating CO2 emissions and sinks is crucial in achieving carbon neutrality in China. However, CO2 emissions from bottom-up inventories are uncertain at regional scales and lack independent verification from atmospheric perspectives. Here we integrated 39 high-precision CO2 stations in China to top-down invert emission-sink variations at 45 km × 45 km and achieved a full range of inventories verification. The results show that China's CO2 emissions are 15% higher than those of five bottom-up inventories, to an annual total of 3.40 Pg C a-1 for 2018-2021. After deducting human and livestock respiration, the annual CO2 emissions were 3.13 Pg C a-1 (11.48 Pg CO2 a-1). The annual increase in emissions slowed from 3.7% in 2019 to 1.1% in 2020 and resumed growth to 4.0% in 2021, consistent with observed CO2 growth rates in China. China's land CO2 sink, deducting farmland sinks and lateral fluxes, was 0.57 Pg C a-1 (2.09 Pg CO2 a-1) for 2018-2021 (higher than most global inverse models), accounting for ∼16.9% of anthropogenic CO2 emissions. The land sink in China decreased by -19.3% in 2019 due to a weak El Niño event and increased by 3.2% in 2020 and 13.7% in 2021. It is worth noting that inverse CO2 emissions and sinks in western China still face large uncertainty due to limited CO2 monitoring. Overall, our top-down estimates demonstrate spatiotemporal variations in CO2 emissions and sinks from atmospheric perspectives and highlight challenges for different provinces in achieving 2060 carbon neutrality with verified estimates.