80-Million-Year Atmospheric CO2 Record from the Late Palaeozoic Ice Age

Atmospheric CO₂ is thought to play a fundamental role in Earth’s climate regulation. Yet, for much of Earth’s deep geological past, atmospheric CO₂ has been poorly constrained, hindering our understanding of transitions between cool and warm climates. Beginning ~370 million years ago in the Late Devonian and ending ~260 million years ago in the Permian, the Late Palaeozoic Ice Age was the last major glaciation preceding the current Late Cenozoic Ice Age and possibly the most intense glaciation witnessed by complex lifeforms. From the onset of the main phase of the Late Palaeozoic Ice Age in the mid-Mississippian ~330 million years ago, the Earth is thought to have sustained glacial conditions, with continental ice accumulating in high to mid-latitudes. However, open questions remain about the role of CO₂ and nature of Earth’s climate during the onset and demise of glacial conditions.

This presentation will showcase an 80-million-year-long boron isotope record within a proxy framework for robust quantification of CO₂, paired with new strontium, carbon and oxygen isotope records. Our records reveal that the main phase of the Late Palaeozoic Ice Age glaciation was maintained by prolonged low CO₂, unprecedented in Earth’s history. About 294 million years ago, atmospheric CO₂ rose abruptly (4-fold), releasing the Earth from its penultimate ice age and transforming the Early Permian into a warmer world. Our findings demonstrate the central role of CO₂ in driving Earth’ geological climatic and environmental transitions [1].

[1] Jurikova H., Garbelli C., Whiteford R., Reeves T., Laker G.M., Liebetrau V., Gutjahr M., Eisenhauer A., Savickaite K., Leng M.J., Iurino D.A., Viaretti M., Tomašových A., Zhang Y., Wang W., Shi G.R., Shen S., Rae J.W.B., Angiolini L. (2025) Rapid rise in atmospheric CO₂ marked the end of the Late Palaeozoic Ice Age. Nature Geosci., https://doi.org/10.1038/s41561-024-01610-2.