1Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, European Way, Southampton, SO14 3ZH, UK
2Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK
3Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
4Biomarine Sciences, Institute of Environmental Biology, Utrecht University, Laboratory of Palaeobotany and Palynology, Budapestlaan 4, 3584CD, Utrecht, The Netherlands
5Departamento de Geologia, Universidad de Oviedo, Arias de Velasco, 33005 Oviedo, Asturias, Spain
*now at: School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, CF10 3AT, Cardiff, UK
Abstract. Late Paleocene and early Eocene hyperthermals are transient warming events associated with massive perturbations of the global carbon cycle, and are considered partial analogues for current anthropogenic climate change. Because the magnitude of carbon release varied between the events, they are natural experiments ideal for exploring the relationship between carbon cycle perturbations, climate change and biotic response. Here we quantify marine biotic variability through three million years of the early Eocene that include five hyperthermals, utilizing a method that allows us to integrate the records of different plankton groups through scenarios ranging from background to major extinction events. Our long time-series calcareous nannoplankton record indicates a scaling of biotic disruption to climate change associated with the amount of carbon released during the various hyperthermals. Critically, only the three largest hyperthermals, the Paleocene–Eocene Thermal Maximum (PETM), Eocene Thermal Maximum 2 (ETM2) and the I1 event, show above-background variance, suggesting that the magnitude of carbon input and associated climate change needs to surpass a threshold value to cause significant biotic disruption.