Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry
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Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry. / Evans, David; Sagoo, Navjit; Renema, Willem; Cotton, Laura; Müller, Wolfgang; Todd, Jonathan A.; Saraswati, Pratul Kumar; Stassen, Peter; Ziegler, Martin; Pearson, Paul; Valdes, Paul J.; Affek, Hagit P.
In: PNAS, Vol. 115, No. 6, 2018, p. 1174-1179.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry
AU - Evans, David
AU - Sagoo, Navjit
AU - Renema, Willem
AU - Cotton, Laura
AU - Müller, Wolfgang
AU - Todd, Jonathan A.
AU - Saraswati, Pratul Kumar
AU - Stassen, Peter
AU - Ziegler, Martin
AU - Pearson, Paul
AU - Valdes, Paul J.
AU - Affek, Hagit P.
PY - 2018
Y1 - 2018
N2 - Past greenhouse periods with elevated atmospheric CO2 were characterized by globally warmer sea-surface temperatures (SST). However, the extent to which the high latitudes warmed to a greater degree than the tropics (polar amplification) remains poorly constrained, in particular because there are only a few temperature reconstructions from the tropics. Consequently, the relationship between increased CO2, the degree of tropical warming, and the resulting latitudinal SST gradient is not well known. Here, we present coupled clumped isotope (Δ47)-Mg/Ca measurements of foraminifera from a set of globally distributed sites in the tropics and midlatitudes. Δ47 is insensitive to seawater chemistry and therefore provides a robust constraint on tropical SST. Crucially, coupling these data with Mg/Ca measurements allows the precise reconstruction of Mg/Casw throughout the Eocene, enabling the reinterpretation of all planktonic foraminifera Mg/Ca data. The combined dataset constrains the range in Eocene tropical SST to 30–36 °C (from sites in all basins). We compare these accurate tropical SST to deep-ocean temperatures, serving as a minimum constraint on high-latitude SST. This results in a robust conservative reconstruction of the early Eocene latitudinal gradient, which was reduced by at least 32 ± 10% compared with present day, demonstrating greater polar amplification than captured by most climate models.
AB - Past greenhouse periods with elevated atmospheric CO2 were characterized by globally warmer sea-surface temperatures (SST). However, the extent to which the high latitudes warmed to a greater degree than the tropics (polar amplification) remains poorly constrained, in particular because there are only a few temperature reconstructions from the tropics. Consequently, the relationship between increased CO2, the degree of tropical warming, and the resulting latitudinal SST gradient is not well known. Here, we present coupled clumped isotope (Δ47)-Mg/Ca measurements of foraminifera from a set of globally distributed sites in the tropics and midlatitudes. Δ47 is insensitive to seawater chemistry and therefore provides a robust constraint on tropical SST. Crucially, coupling these data with Mg/Ca measurements allows the precise reconstruction of Mg/Casw throughout the Eocene, enabling the reinterpretation of all planktonic foraminifera Mg/Ca data. The combined dataset constrains the range in Eocene tropical SST to 30–36 °C (from sites in all basins). We compare these accurate tropical SST to deep-ocean temperatures, serving as a minimum constraint on high-latitude SST. This results in a robust conservative reconstruction of the early Eocene latitudinal gradient, which was reduced by at least 32 ± 10% compared with present day, demonstrating greater polar amplification than captured by most climate models.
U2 - 10.1073/pnas.1714744115
DO - 10.1073/pnas.1714744115
M3 - Journal article
VL - 115
SP - 1174
EP - 1179
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 6
ER -
ID: 315593350