Last glacial atmospheric CO(2)decline due to widespread Pacific deep-water expansion

Carbon-rich Pacific deep water extended into the South Atlantic some 38,000 to 28,000 years ago, potentially contributing to a reduction in atmospheric carbon dioxide and the onset of the Last Glacial Maximum, according to deep-water carbonate chemistry reconstructions. Ocean circulation critically...

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Bibliographic Details
Published in:Nature Geoscience
Main Authors: Yu, J., Menviel, L., Jin, Z. D., Anderson, R. F., Jian, Z., Piotrowski, A. M., Ma, X., Rohling, E. J., Zhang, F., Marino, G., McManus, J. F.
Format: Report
Language:English
Published: NATURE PUBLISHING GROUP 2020
Subjects:
EASTERN EQUATORIAL PACIFIC
SOUTHERN-OCEAN
NORTH-ATLANTIC
OVERTURNING CIRCULATION
CARBON
CO2
SEA
SEQUESTRATION
STRATIFICATION
TEMPERATURE
Geology
Geosciences
Multidisciplinary
Pacific
Southern Ocean
North Atlantic
Online Access:http://ir.ieecas.cn/handle/361006/15091
https://doi.org/10.1038/s41561-020-0610-5
Description
Summary:Carbon-rich Pacific deep water extended into the South Atlantic some 38,000 to 28,000 years ago, potentially contributing to a reduction in atmospheric carbon dioxide and the onset of the Last Glacial Maximum, according to deep-water carbonate chemistry reconstructions. Ocean circulation critically affects the global climate and atmospheric carbon dioxide through redistribution of heat and carbon in the Earth system. Despite intensive research, the nature of past ocean circulation changes remains elusive. Here we present deep-water carbonate ion concentration reconstructions for widely distributed locations in the Atlantic Ocean, where low carbonate ion concentrations indicate carbon-rich waters. These data show a low-carbonate-ion water mass that extended northward up to about 20 degrees S in the South Atlantic at 3-4 km depth during the Last Glacial Maximum. In combination with radiocarbon ages, neodymium isotopes and carbon isotopes, we conclude that this low-carbonate-ion signal reflects a widespread expansion of carbon-rich Pacific deep waters into the South Atlantic, revealing a glacial deep Atlantic circulation scheme different than commonly considered. Comparison of high-resolution carbonate ion records from different water depths in the South Atlantic indicates that this Pacific deep-water expansion developed from approximately 38,000 to 28,000 years ago. We infer that its associated carbon sequestration may have contributed critically to the contemporaneous decline in atmospheric carbon dioxide, thereby helping to initiate the glacial maximum.

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