Prof Petersen was quoted in a science journalism piece in Ars Tecnica covering a recent high profile paper involving clumped isotopes by Meckler and coauthors published in Science Magazine. In that study, Meckler et al applied the clumped isotope paleothermometer to benthic forams from a sediment core in the Atlantic, taking the first steps towards recreating the iconic “Zachos curve” using this improved paleothermometer.
The Zachos curve has been used by many to describe global trends in climate over the Cenozoic (last ~66 million years). However, this curve is based on the d18O paleothermometer, which combines the influences of changing bottom water temperature (a proxy for global temperature) and changing global ice volume. If ice gets trapped on land in ice sheets and glaciers, the remaining seawater gets isotopically enriched, changing d18O values in benthic forams even with no temperature change. From just d18O measurements, it is impossible to separate the contributions of changing temperature and ice volume.
Meckler et al found bottom water temperatures during peak greenhouse periods were much warmer than previously determined. This is a very exciting result and shows the power and promise of using this improved paleothermometry technique for paleoceanography, especially during periods of changing or unknown global ice volume.
We hope that this work will continue and more similar records will be produced for sediment cores around the world, building a picture of global bottom water temperatures through the Cenozoic, unencumbered by uncertainties in ice volume.