Rapid warming in Eocene shares features with glacial cycles
The researchers looked at the Eocene, a time when the climate in general was much warmer than it is now; the period was also dominated by the Paleocene-Eocene Thermal Maximum, when the planet experienced a relatively sudden warming of 5-7°C. It wasn’t the only event of its kind, though. A variety of studies have identified a number of smaller events, called “hyperthermals,” that were typically 2-4°C warmer than the surrounding period.
The new paper focuses on a sediment core from the Atlantic that covers 2.4 million years of the Eocene, starting about 50 million years ago; where possible, the data was confirmed using a sample from the Pacific, which indicated whether the trends in the Atlantic were global. In this record, the authors identify over a dozen hyperthermal events, indicating they were much more common that had previously been suspected. Each warming event was accompanied by changes to the planet’s carbon cycle. (Both temperature and carbon cycle status are derived from isotope ratios within the sample.)