Wu et al. (2021)
Also: Wu et al. 2021
Six-fold increase of atmospheric pCO2 during the Permian–Triassic mass extinction
Wu, Y., Chu, D., Tong, J., Song, H., Dal Corso, J., Wignall, P.B., Song, H., Du, Y. & Cui, Y. (2021). Six-fold increase of atmospheric pCO2 during the Permian–Triassic mass extinction. Nature Communications. 12(1). PDF
https://doi.org/10.1038/s41467-021-22298-7
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.