Bennedsen Mikkel, Hillebrand Eric, Koopman Siem Jan
Department of Economics and Business Economics, Aarhus University, Aarhus V, Denmark.
Center for Research in Energy: Economics and Markets (CoRE), Aarhus University, Aarhus V, Denmark.
Nat Commun. 2024 Oct 1;15(1):8507. doi: 10.1038/s41467-024-52728-1.
The global fraction of anthropogenically emitted carbon dioxide (CO) that stays in the atmosphere, the CO airborne fraction, has been fluctuating around a constant value over the period 1959 to 2022. The consensus estimate of the airborne fraction is around 44%. In this study, we show that the conventional estimator of the airborne fraction, based on a ratio of changes in atmospheric CO concentrations and CO emissions, suffers from a number of statistical deficiencies. We propose an alternative regression-based estimator of the airborne fraction that does not suffer from these deficiencies. Our empirical analysis leads to an estimate of the airborne fraction over 1959-2022 of 47.0% (± 1.1%; 1σ), implying a higher, and better constrained, estimate than the current consensus. Using climate model output, we show that a regression-based approach provides sensible estimates of the airborne fraction, also in future scenarios where emissions are at or near zero.
1959年至2022年期间，人为排放的二氧化碳（CO）滞留在大气中的全球占比，即CO的空气传播分数，一直在一个恒定值附近波动。空气传播分数的共识估计约为44%。在本研究中，我们表明，基于大气CO浓度变化与CO排放之比的传统空气传播分数估计器存在一些统计缺陷。我们提出了一种基于回归的空气传播分数替代估计器，该估计器不存在这些缺陷。我们的实证分析得出，1959 - 2022年期间空气传播分数的估计值为47.0%（±1.1%；1σ），这意味着比当前的共识估计值更高且约束更好。利用气候模型输出结果，我们表明，基于回归的方法在排放为零或接近零的未来情景中，也能提供合理的空气传播分数估计值。
