Measuring temperatures from Earth’s past is important for understanding the development of its climate. Ancient ocean temperatures are most commonly reconstructed by analysing the ratio of different oxygen atoms in the calcium carbonate remains of fossils. However, this presents many challenges, including a combination of biological processes known as “vital effects” which are very noticeable in corals and can affect the data. Andres Rüggeberg from the University of Fribourg was part of the research team led by the University of Göttingen. This study shows how the abundance of a third, very rare oxygen isotope can uncover whether the isotopic composition was solely influenced by temperature or if biological effects also played a role. The results were published in Geochemical Perspective Letters.

The image shows the coral Desmophyllum pertusum, one of the species analysed to refine the method to measure temperatures from the past (Photo credits: Helmholtz Centre for Ocean Research Kiel (GEOMAR) / JAGO Team Poseidon Cruise 391 Lopphavet Reef).

Original publication: Bajnai, D., Klipsch, S., Davies, A.J., Raddatz, J., Gischler, E., Rüggeberg, A., Pack, A., Herwartz, D. (2024) “Correcting for vital effects in coral carbonate using triple oxygen isotopes”. Geochemical Perspectives Letters v31. DOI: 10.7185/geochemlet.2430