Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

Raquel A. Lopes dos Santos; Matthias Prange; Isla S. Castaneda; Enno Schefuss; Stefan Mulitza; Michael Schulz; Eva M. Niedermeyer; Jaap S. Sinninghe Damste; Stefan Schouten

doi:10.1016/j.epsl.2010.10.030

Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

Raquel A. Lopes dos Santos
, Matthias Prange
, Isla S. Castaneda
, Enno Schefuss
, Stefan Mulitza
, Michael Schulz
, Eva M. Niedermeyer
, Jaap S. Sinninghe Damste
, Stefan Schouten

Utrecht University
University of Bremen
extern

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

Changes in the strength of Atlantic meridional overturning circulation (AMOC) are known to have profound impacts on global climate. Coupled modelling studies have suggested that, on annual to multi-decadal time scales, a slowdown of AMOC causes a deepening of the thermocline in the tropical Atlantic. However, this process has been poorly constrained by sedimentary geochemical records. Here, we reconstruct surface (U-37(K) Index) and thermocline (TEX86H) water temperatures from the Guinea Plateau Margin (Eastern tropical Atlantic) over the last two glacial-interglacial cycles (similar to 192 kyr). These paleotemperature records show that periods of reduced AMOC, as indicated by the delta C-13 benthic foraminiferal record from the same core, coincide with a reduction in the near-surface vertical temperature gradient, demonstrating for the first time that AMOC-induced tropical Atlantic thermocline adjustment exists on longer, millennial time scales. Modelling results support the interpretation of the geochemical records and show that thermocline adjustment is particularly pronounced in the eastern tropical Atlantic. Thus, variations in AMOC strength appear to be an important driver of the thermocline structure in the tropical Atlantic from annual to multi-millennial time scales. (C) 2010 Elsevier B.V. All rights reserved.

Original language	English
Pages (from-to)	407-414
Number of pages	8
Journal	Earth and Planetary Science Letters
Volume	300
Issue number	3-4
DOIs	https://doi.org/10.1016/j.epsl.2010.10.030
Publication status	Published - 1 Dec 2010
Externally published	Yes

Funding

We thank two anonymous reviewers and editor P. Delaney for comments which improved the manuscript. We thank Marianne Baas, Ellen Hopmans, Jort Ossebaar and Michiel Kienhuis for analytical assistance with the organic geochemical analyses, and Monika Segl for assistance with the foraminiferal isotope analyses. Research funding was provided by NEBROC-2 and a VICI grant to SS from the Netherlands Organization of Scientific Research. ES, MP, SM, MS and EMN have been funded through the DFG-Research Center/Excellence Cluster "The Ocean in the Earth System". Samples from GeoB9528-3 were supplied through the assistance of MARUM at the University of Bremen.

Funders
DFG-Research Center/Excellence Cluster

Keywords

Atlantic meridional overturning circulation thermocline
Tex86
U-37(k)

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10.1016/j.epsl.2010.10.030

Cite this

dos Santos, R. A. L., Prange, M., Castaneda, I. S., Schefuss, E., Mulitza, S., Schulz, M., Niedermeyer, E. M., Damste, J. S. S., & Schouten, S. (2010). Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic. Earth and Planetary Science Letters, 300(3-4), 407-414. https://doi.org/10.1016/j.epsl.2010.10.030

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abstract = "Changes in the strength of Atlantic meridional overturning circulation (AMOC) are known to have profound impacts on global climate. Coupled modelling studies have suggested that, on annual to multi-decadal time scales, a slowdown of AMOC causes a deepening of the thermocline in the tropical Atlantic. However, this process has been poorly constrained by sedimentary geochemical records. Here, we reconstruct surface (U-37(K) Index) and thermocline (TEX86H) water temperatures from the Guinea Plateau Margin (Eastern tropical Atlantic) over the last two glacial-interglacial cycles (similar to 192 kyr). These paleotemperature records show that periods of reduced AMOC, as indicated by the delta C-13 benthic foraminiferal record from the same core, coincide with a reduction in the near-surface vertical temperature gradient, demonstrating for the first time that AMOC-induced tropical Atlantic thermocline adjustment exists on longer, millennial time scales. Modelling results support the interpretation of the geochemical records and show that thermocline adjustment is particularly pronounced in the eastern tropical Atlantic. Thus, variations in AMOC strength appear to be an important driver of the thermocline structure in the tropical Atlantic from annual to multi-millennial time scales. (C) 2010 Elsevier B.V. All rights reserved.",

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dos Santos, RAL, Prange, M, Castaneda, IS, Schefuss, E, Mulitza, S, Schulz, M, Niedermeyer, EM, Damste, JSS & Schouten, S 2010, 'Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic', Earth and Planetary Science Letters, vol. 300, no. 3-4, pp. 407-414. https://doi.org/10.1016/j.epsl.2010.10.030

Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic. / dos Santos, Raquel A. Lopes; Prange, Matthias; Castaneda, Isla S. et al.
In: Earth and Planetary Science Letters, Vol. 300, No. 3-4, 01.12.2010, p. 407-414.

Research output: Contribution to journal › Article › Academic › peer-review

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T1 - Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

AU - dos Santos, Raquel A. Lopes

AU - Prange, Matthias

AU - Castaneda, Isla S.

AU - Schefuss, Enno

AU - Mulitza, Stefan

AU - Schulz, Michael

AU - Niedermeyer, Eva M.

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AU - Schouten, Stefan

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ER -

Glacial-interglacial variability in Atlantic meridional overturning circulation and thermocline adjustments in the tropical North Atlantic

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