A sediment core reopens a question about the last warm period

A sediment core recovered from a basin off the shelf edge in 2024 preserves the last interglacial period — roughly 125,000 years ago — in better condition than any material previously available to the paleoceanography group, and it disagrees with the regional reconstruction assembled from shallower sites.

The last interglacial matters because it is the most recent period when the climate was somewhat warmer than today and sea level was several meters higher. It is the nearest thing to an observed analogue for a warmer world, and the regional detail is contested.

"The core disagrees with the picture," said Tobias Wren, who leads the work. "That is not the same as the core being right. A deeper site has different preservation, different sedimentation rate and a different set of things that can go wrong with the chronology. Working out which of those explains the disagreement is the whole job."

One paper has been published on the record. Wren describes the second as "still arguing with itself."

Undergraduates in marine geoscience work on the core material directly rather than on teaching sets, and the record is now the extended case in GEOL 470 Paleoceanography, where age model construction is treated as a first-order problem rather than a preliminary step.