Eocene maar sediments record warming of up to 3.5 °C during a hyperthermal event 47.2 million years ago

A new study reveals that the Eocene hyperthermal event C21n-H1, occurring 47.2 million years ago, led to a rapid warming of up to 3.5 °C on continental regions. This finding challenges previous assumptions about the magnitude and pace of such events, which were primarily derived from marine records. Researchers analyzed terrestrial biomarkers and carbon isotopes from varved lake deposits in the UNESCO World Heritage site 'Messel Fossil Pit' (Germany), providing a high-resolution record of sub-millennial to millennial-scale temperature changes. The study suggests that the warming was driven by two factors: the massive release of greenhouse gases and half-precession orbital forcing, indicated by ~12,000-year temperature cycles. Additionally, a sharp decrease in carbon isotopes at the hyperthermal peak corresponds to increased organic carbon content and shifts in lake algal communities, offering insights into the ecological impacts of such events.

Schmitt, C., Vasiliev, I., Meijer, N., Brugger, J., Kaboth-Bahr, S., Bahr, A., & Mulch, A. (2024). Eocene maar sediments record warming of up to 3.5 °C during a hyperthermal event 47.2 million years ago. Communications Earth & Environment, 5(1). https://doi.org/10.1038/s43247-024-01628-9