Extreme warmth and heat-stressed plankton in the tropics during the Paleocene-Eocene Thermal Maximum

• Published in: Science advances Vol. 3; no. 3; p. e1600891
• Main Authors: Frieling, Joost, Gebhardt, Holger, Huber, Matthew, Adekeye, Olabisi A, Akande, Samuel O, Reichart, Gert-Jan, Middelburg, Jack J, Schouten, Stefan, Sluijs, Appy
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 01.03.2017
• Subjects: Climatology; Fossils; Global Warming; Heat-Shock Response - physiology; Plankton - physiology; SciAdv r-articles; heat; temperature proxy; heat stress; paleocence - eocene; Plankton; polar amplification; SST; PETM; dinoflagellate; Tropics
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.1600891

Global ocean temperatures rapidly warmed by ~5°C during the Paleocene-Eocene Thermal Maximum (PETM; ~56 million years ago). Extratropical sea surface temperatures (SSTs) met or exceeded modern subtropical values. With these warm extratropical temperatures, climate models predict tropical SSTs >35°C-near upper physiological temperature limits for many organisms. However, few data are available to test these projected extreme tropical temperatures or their potential lethality. We identify the PETM in a shallow marine sedimentary section deposited in Nigeria. On the basis of planktonic foraminiferal Mg/Ca and oxygen isotope ratios and the molecular proxy [Formula: see text], latest Paleocene equatorial SSTs were ~33°C, and [Formula: see text] indicates that SSTs rose to >36°C during the PETM. This confirms model predictions on the magnitude of polar amplification and refutes the tropical thermostat theory. We attribute a massive drop in dinoflagellate abundance and diversity at peak warmth to thermal stress, showing that the base of tropical food webs is vulnerable to rapid warming.