Atlantic Circulation and Ice Sheet Influences on Upper South Atlantic Temperature During the Last Deglaciation

Atlantic Meridional Overturning Circulation (AMOC) disruption during the last deglaciation is hypothesized to have caused large subsurface ocean temperature anomalies, but records from key regions are not available to test this hypothesis, and other possible drivers of warming have not been fully co...

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Bibliographic Details
Published in:Paleoceanography and Paleoclimatology
Main Authors: Umling, N. E., Oppo, D. W., Chen, P., Yu, J., Liu, Z., Yan, M., Gebbie, G., Lund, D. C., Pietro, K. R., Jin, Z. D., Huang, K-F, Costa, K. B., Toledo, F. A. L.
Format: Report
Language:English
Published: AMER GEOPHYSICAL UNION 2019
Subjects:
WATER MASS GEOMETRY
ATMOSPHERIC CO2
CARBON-ISOTOPE
OCEAN CIRCULATION
NORTH-ATLANTIC
OVERTURNING CIRCULATION
BENTHIC FORAMINIFERA
INTERMEDIATE WATERS
GLACIAL MAXIMUM
CLIMATE
Geology
Oceanography
Paleontology
Geosciences
Multidisciplinary
Ice Sheet
North Atlantic
Online Access:http://ir.ieecas.cn/handle/361006/13708
http://ir.ieecas.cn/handle/361006/13709
https://doi.org/10.1029/2019PA003558
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Summary:Atlantic Meridional Overturning Circulation (AMOC) disruption during the last deglaciation is hypothesized to have caused large subsurface ocean temperature anomalies, but records from key regions are not available to test this hypothesis, and other possible drivers of warming have not been fully considered. Here, we present the first reliable evidence for subsurface warming in the South Atlantic during Heinrich Stadial 1, confirming the link between large-scale heat redistribution and AMOC. Warming extends across the Bolling-Allerod despite predicted cooling at this time, thus spanning intervals of both weak and strong AMOC indicating another forcing mechanism that may have been previously overlooked. Transient model simulations and quasi-conservative water mass tracers suggest that reduced northward upper ocean heat transport was responsible for the early deglacial (Heinrich Stadial 1) accumulation of heat at our shallower (similar to 1,100 m) site. In contrast, the results suggest that warming at our deeper site (similar to 1,900 m) site was dominated by southward advection of North Atlantic middepth heat anomalies. During the Bolling-Allerod, the demise of ice sheets resulted in oceanographic changes in the North Atlantic that reduced convective heat loss to the atmosphere, causing subsurface warming that overwhelmed the cooling expected from an AMOC reinvigoration. The data and simulations suggest that rising atmospheric CO2 did not contribute significantly to deglacial subsurface warming at our sites.

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