Surface Ocean Cooling in the Eocene North Atlantic Coincides With Declining Atmospheric CO 2

• Published in: Geophysical Research Letters
• Other Authors: Inglis, Gordon N. (author), Bhatia, Rehemat (author), Evans, David (author), Zhu, Jiang (author), Müller, Wolfgang (author), Mattey, David (author), Thornalley, David J. R. (author), Stockey, Richard G. (author), Wade, Bridget S. (author)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2023
• Subjects: North Atlantic
• Online Access: https://doi.org/10.1029/2023GL105448

The Eocene (56-34 million years ago) is characterized by declining sea surface temperatures (SSTs) in the low latitudes (similar to 4 degrees C) and high southern latitudes (similar to 8-11 degrees 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, delta O-18, TEX86) SST record from Bass River in the western North Atlantic. Our compiled multi-proxy SST record confirms a net decline in SSTs (similar to 4 degrees C) between the early Eocene Climatic Optimum (53.3-49.1 Ma) and mid-Eocene (similar to 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. 2202777