Major sea level fall during the Pliocene M2 glaciation.
basic_science · Level V
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- Record sourced from PubMed, PMID 40819061.
- Also identified by DOI 10.1038/s41467-025-62446-x and PMC identifier 12357856.
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Abstract
The extent of ice growth during the Pliocene M2 glaciation (~3.3 Ma) has been called into question, with benthic foraminiferal oxygen isotope records interpreted primarily as a cooling signal. Here we improve the benthic foraminiferal Mg/Ca paleothermometer, allowing bottom water temperature reconstructions with a precision of ±0.2-0.3°C (1 s.d.). Applying this approach to M2 implies a significant increase in ice volume (~55 m SLE) that was more tightly coupled to a drop in CO<sub>2</sub> than to ocean temperature. We suggest that the M2 glaciation was driven by a reduction in northern hemisphere poleward heat transport, and amplified by a reduction in southern hemisphere poleward heat transport caused by restriction of the Indonesian Seaway. The cryosphere growth drove the atmospheric CO<sub>2</sub> decrease, which likely contributed to the overall magnitude of ice growth. These results demonstrate the sensitivity of the cryosphere to changes in ocean heat transport in a similar to modern climate.