Extreme warmth and heat-stressed plankton in the tropics during the
Paleocene-Eocene Thermal Maximum
#MMPMID28275727
Frieling J
; Gebhardt H
; Huber M
; Adekeye OA
; Akande SO
; Reichart GJ
; Middelburg JJ
; Schouten S
; Sluijs A
Sci Adv
2017[Mar]; 3
(3
): e1600891
PMID28275727
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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.
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