Scientists reconstruct atmospheric carbon dioxide levels of ice-free periods of Earth's history using proxies such as stomatal density in fossil leaves, paleosol carbonates, boron isotopes in marine carbonates, and alkenones.

Is it true that scientists reconstruct atmospheric carbon dioxide levels of ice-free periods of Earth's history using proxies such as stomatal density in fossil leaves, paleosol carbonates, boron isotopes in marine carbonates, and alkenones?

Unclear. Several sources confirm individual proxies for reconstructing ancient atmospheric CO2: paleosol carbonates, stomatal index in fossil leaves, and boron isotopes in marine carbonates. None of the retrieved items covers all four proxies named in the claim, and no item addresses alkenones.

Verdict: PARTIAL LEAN · 4 sources for, 0 against · Last checked 2 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Walker, J. C. (1995). There is more to climate than carbon dioxide.. doi.org. https://doi.org/10.1029/95rg00346

Low CO2 levels of the entire Pleistocene epoch - PMC Lock. (n.d.). pmc.ncbi.nlm.nih.gov. https://doi.org/10.1038/s41467-019-12357-5

Tesfamichael, T. (2023). Late Oligocene atmospheric carbon dioxide concentrations reconstructed from fossil leaves using stomatal index. doi.org. https://doi.org/10.54991/jop.2023.1860

Passey, B. H. (2012). Reconstructing Terrestrial Environments Using Stable Isotopes in Fossil Teeth and Paleosol Carbonates. doi.org. https://doi.org/10.1017/s1089332600002606