Abstract. The global budgets of CO₂ and of excess CO₂ (i.e., above preindustrial) in the biogeosphere are examined by a top-down, observationally constrained approach. Global stocks in the atmosphere, mixed-layer and deep ocean, and labile and obdurate terrestrial biosphere, and fluxes between them are quantified; total uptake of carbon by the terrestrial biosphere is constrained by observations, but apportionment to the two terrestrial compartments is only weakly constrained, requiring examination of sensitivity to this apportionment. Because of near equilibrium between the atmosphere and the mixed-layer ocean and near steady state between the atmosphere and the labile biosphere, these three compartments are tightly coupled. For best-estimate present-day anthropogenic emissions the turnover time of excess carbon in these compartments to the deep ocean and obdurate biosphere is 67 to 158 years. Atmospheric CO₂ over the Anthropocene is accurately represented by a five-compartment model with four independent parameters: two universal geophysical quantities and two, specific to CO₂, treated as variable. The model also accurately represents atmospheric radiocarbon, particularly the large increase due to atmospheric testing of nuclear weapons and the subsequent decrease. The adjustment time of excess atmospheric CO₂, evaluated from the rate of decrease following abrupt cessation of emissions, is 78 to 140 years, consistent with the turnover time, approaching a long-time floor of 15–20 % of the value at the time of cessation. The lifetime of excess CO₂ found here, several-fold shorter than estimates from current carbon-cycle models, indicates that cessation of anthropogenic emissions atmospheric would result in substantial recovery of CO₂ toward its preindustrial value in less than a century.

中文翻译：

---

基于观测的过量大气二氧化碳的预算和寿命

摘要。CO ₂和过量 CO ₂的全球预算（即，高于工业化前）在生物地圈中通过自上而下的观察约束方法进行检查。对大气、混合层和深海以及不稳定和顽固的陆地生物圈中的全球存量及其之间的通量进行量化；陆地生物圈对碳的总吸收受到观测的限制，但对两个陆地隔间的分配只受到微弱的限制，需要检查对这种分配的敏感性。由于大气与混合层海洋之间接近平衡，大气与不稳定生物圈之间接近稳定状态，这三个区室紧密耦合。为了最好地估计当今的人为排放，这些隔间中过量碳到深海和顽固生物圈的周转时间为 67 到 158 年。人类世上的₂由具有四个独立参数的五室模型准确表示：两个通用地球物理量和两个特定于 CO _{2 的}变量，被视为变量。该模型还准确地表示了大气放射性碳，特别是由于核武器大气试验导致的大幅增加和随后的减少。大气CO ₂过量调整时间，根据突然停止排放后的下降率计算，为78～140年，与周转时间一致，接近当时值的15～20%的长期底线的停止。过量 CO ₂的寿命这里发现的比当前碳循环模型的估计值短几倍，表明停止人为排放大气将导致 CO ₂在不到一个世纪的时间内大幅恢复到工业化前的价值。