关键词: 碳中和, 气候中和, CO₂移除, 非等价性, 碳循环反馈

Abstract: Net-zero emissions CO₂ accounting commonly assumes that one tonne of CO₂ removed from the atmosphere can fully offset one tonne of CO₂ emitted, but CO₂ emissions and removals are not completely equivalent in terms of their climatic effects. Taking net-zero accounting as the point of departure, this review synthesizes recent progress in research on the durability of carbon storage, biogeophysical effects, associated non-CO₂ greenhouse gas emissions, asymmetric Earth system responses to positive and negative CO₂ fluxes, and life-cycle assessment. It further assesses the key scientific challenges involved in moving from carbon-neutrality accounting toward climate-neutrality assessment. The climatic effects of carbon dioxide removal depend not only on the amount of CO₂ removed, but also on the properties of the storage reservoir, the relevant time scale, the spatial pattern of deployment, associated non-CO₂ greenhouse gas emissions, changes in the surface energy budget, and feedbacks within the Earth system. Existing studies have identified multiple mechanisms through which emissions and removals are non-equivalent. However, systematic quantification remains insufficient for coupled mechanisms, regional heterogeneity, and long-term reversibility. Developing an integrated accounting framework oriented toward climate neutrality would help support the deployment of carbon dioxide removal and the assessment of its climate benefits in the context of China’s carbon peaking and carbon neutrality goals.

Key words: Carbon neutrality, Climate neutrality, Carbon dioxide removal, Non-equivalence, Carbon cycle feedback