Carbon isotope budget indicates biological disequilibrium dominated ocean carbon storage at the Last Glacial Maximum.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39266526.
- Also identified by DOI 10.1038/s41467-024-52360-z and PMC identifier 11393407.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Understanding the causes of the ~90 ppmv atmospheric CO<sub>2</sub> swings between glacial and interglacial climates is an important open challenge in paleoclimate research. Although the regularity of the glacial-interglacial cycles hints at a single driving mechanism, Earth System models require many independent physical and biological processes to explain the full observed CO<sub>2</sub> signal. Here we show that biologically sequestered carbon in the ocean can explain an atmospheric CO<sub>2</sub> change of 75 ± 40 ppmv, based on a mass balance calculation using published carbon isotopic measurements. An analysis of the carbon isotopic signatures of different water masses indicates similar regenerated carbon inventories at the Last Glacial Maximum and during the Holocene, requiring that the change in carbon storage was dominated by disequilibrium. We attribute the inferred change in carbon disequilibrium to expansion of sea-ice or change in the overturning circulation.