Surface Ocean Cooling in the Eocene North Atlantic Coincides With Declining Atmospheric CO2

Gordon Inglis, Rehemat Bhatia, David Evans, Jiang Zhu, Wolfgang Müller, Dave Mattey, David Thornalley, Richard G Stockey, Bridget S. Wade

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The Eocene (56–34 million years ago) is characterized by declining sea surface temperatures (SSTs) in the low latitudes (∼4°C) and high southern latitudes (∼8–11°C), in accord with decreasing CO2 estimates. However, in the mid-to-high northern latitudes there is no evidence for surface water cooling, suggesting thermal decoupling between northern and southern hemispheres and additional non-CO2 controls. To explore this further, we present a multi-proxy (Mg/Ca, δ18O, TEX86) SST record from Bass River in the western North Atlantic. Our compiled multi-proxy SST record confirms a net decline in SSTs (∼4°C) between the early Eocene Climatic Optimum (53.3–49.1 Ma) and mid-Eocene (∼44–41 Ma), supporting declining atmospheric CO2 as the primary mechanism of Eocene cooling. However, from the mid-Eocene onwards, east-west North Atlantic temperature gradients exhibit different trends, which we attribute to incursion of warmer waters into the eastern North Atlantic and inception of Northern Component Water across the early-middle Eocene transition.
Original languageEnglish
Article numbere2023GL105448
JournalGeophysical Research Letters
Issue number24
Early online date23 Dec 2023
Publication statusPublished - 28 Dec 2023

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