<p>CO₂ emission volume is used as a mainstream index when considering the climate goals either in modeling practices or in each round of climate negotiation. CO₂ concentration can provide micro-level evidence of CO₂ emission, while it hasn’t been included in national decarbonization pledge. The lack of a CO₂ “concentration-emission” coupling framework hinders the incorporation of CO₂ concentration in climate mitigation policy formulation. In this study, we construct a CO₂ “concentration-emission” coupling framework, which allows us to examine China’s carbon neutrality target from the perspective of CO₂ concentration. The framework is intended as a national-scale diagnostic tool rather than a source-attribution model. By using Atmospheric background station data, we find that: (1) Compared with scenario that implements current policy (CPS), there are around 103.9 Gt of CO₂ emission gap cumulatively under scenario that achieve carbon neutrality (CNS). (2) By 2060, China’s artificial carbon sink capacity is required to reach a magnitude of 2.91 Gt/year, which is higher than results from the previous study. (3) The 450 ppm target will be largely surpassed even under CNS scenario. These findings indicate that concentration information can provide a valuable supplementary early warning and calibration signal for national carbon mitigation policy.</p>