A regression-based approach to the CO<sub>2</sub> airborne fraction.
Where this comes from
- Record sourced from PubMed, PMID 39353966.
- Also identified by DOI 10.1038/s41467-024-52728-1 and PMC identifier 11445245.
- Licence recorded as CC BY-NC-ND.
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Abstract
The global fraction of anthropogenically emitted carbon dioxide (CO<sub>2</sub>) that stays in the atmosphere, the CO<sub>2</sub> 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<sub>2</sub> concentrations and CO<sub>2</sub> 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.