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Enhanced Poleward Flux of Atmospheric Moisture to the Weddell Sea Region (ODP Site 690) During the Paleocene‐Eocene Thermal Maximum
Author(s) -
Kozdon Reinhard,
Penman Donald E.,
Kelly D. C.,
Zachos J. C.,
Fournelle John H.,
Valley J. W.
Publication year - 2020
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2019pa003811
Subject(s) - geology , precipitation , seawater , climatology , sea surface temperature , salinity , flux (metallurgy) , oceanography , moisture , sea level , physics , materials science , meteorology , metallurgy , composite material
Earth's hydrological cycle was profoundly perturbed by massive carbon emissions during an ancient (56 Ma) global warming event referred to as the Paleocene‐Eocene thermal maximum (PETM). One approach to gaining valuable insight into the response of the hydrological cycle is to construct sea‐surface salinity (SSS) records that can be used to gauge changes in the rates of evaporation and precipitation during the PETM in such climatically sensitive areas as the circum‐Antarctic region. Here, we pair oxygen isotope (δ 18 O) and magnesium‐calcium (Mg/Ca) measurements to reconstruct PETM sea‐surface temperatures (SSTs) and δ 18 O composition of seawater (δ 18 O sw ) at austral Site 690 (Weddell Sea). Several discrepancies emerge between the δ 18 O‐ and Mg/Ca‐based SST records, with the latter indicating that the earliest PETM was punctuated by a short‐lived ~4°C increase in local SSTs. Conversion of the δ 18 O sw values to SSS reveals a ~4 ppt decrease ~50 ka after peak PETM warming at Site 690. This negative SSS (δ 18 O sw ) anomaly coincides with a prominent minimum in the planktic foraminifer δ 18 O record published for the Site 690 PETM section. Thus, our revised interpretation posits that this δ 18 O minimum signals a decrease in surface‐ocean δ 18 O sw fostered by a transient increase in mean annual precipitation in the Weddell Sea region. The results of this study corroborate the view that the poleward flux of atmospheric moisture temporarily increased during a distinctive stage of the PETM.