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Glacial–interglacial changes in equatorial Pacific surface-water structure during the Plio–Pleistocene intensification of Northern Hemisphere Glaciation

Glacial–interglacial changes in equatorial Pacific surface-water structure during the Plio–Pleistocene intensification of Northern Hemisphere Glaciation
Glacial–interglacial changes in equatorial Pacific surface-water structure during the Plio–Pleistocene intensification of Northern Hemisphere Glaciation
The late Pliocene/early Pleistocene intensification of Northern Hemisphere Glaciation (iNHG) represents the most recent major tipping point in Earth's climate history. In the equatorial Pacific, the iNHG has been suggested to mark the transition from a warm Pliocene climate state, in which the Pacific warm pool was greatly expanded relative to today giving rise to a surface ocean temperature field akin to modern El Niño conditions, to a climate state with strong upwelling in the east of the basin and stronger zonal temperature gradients. Here we examine this transition by presenting new high-resolution (∼800 yr) planktic foraminiferal Mg/Ca- and δ18δ18O-based sea-surface temperature (SST) and salinity (SSS; based on δ18Oδ18O residuals [δ18Oivc-swδ18Oivc-sw]) records from Eastern Equatorial Pacific (EEP) Ocean Drilling Program Site 849 spanning ∼2.75–2.4 Ma. Our study interval contains the first large-amplitude (∼1‰ in benthic δ18δ18O) early Pleistocene glacial–interglacial cycles (Marine Isotope Stages 100–96) representing the culmination of iNHG. In this study we investigate west-to-east equatorial Pacific SST and SSS gradients. We find that the zonal SST gradient increased by ∼1.5 °C from ∼2.75 to ∼2.4 Ma through EEP cooling. No glacial–interglacial pattern is seen in this gradient. On the other hand, we document obliquity-paced oscillations in the δ18Oivc-swδ18Oivc-sw (SSS) gradient. We hypothesize that these oscillations originated from a response to a glacial southward and interglacial northward migration of the Intertropical Convergence Zone over the EEP.
0012-821X
69-80
Jakob, Kim A.
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Bolton, Clara T.
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Wilson, Paul A.
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Bahr, André
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Pross, Jörg
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Fiebig, Jens
2002fcc6-8c97-4f72-9f07-76efa9bd89ee
Kähler, Karsten
b258aad0-c4fb-49ea-a175-d9bb05ebc30c
Friedrich, Oliver
680f066c-a4b1-4647-beb3-281addc1ee17
Jakob, Kim A.
8c240dc3-b25a-4bd4-a9c1-b8436f1e6ffa
Bolton, Clara T.
24faf2b8-2771-4111-8dc3-46b86beb3d65
Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Bahr, André
ff113c9b-74d3-40e1-ba22-0ddb05ffda5e
Pross, Jörg
7c848424-852f-467b-90f0-19d4f8d4ae01
Fiebig, Jens
2002fcc6-8c97-4f72-9f07-76efa9bd89ee
Kähler, Karsten
b258aad0-c4fb-49ea-a175-d9bb05ebc30c
Friedrich, Oliver
680f066c-a4b1-4647-beb3-281addc1ee17

Jakob, Kim A., Bolton, Clara T., Wilson, Paul A., Bahr, André, Pross, Jörg, Fiebig, Jens, Kähler, Karsten and Friedrich, Oliver (2017) Glacial–interglacial changes in equatorial Pacific surface-water structure during the Plio–Pleistocene intensification of Northern Hemisphere Glaciation. Earth and Planetary Science Letters, 463, 69-80. (doi:10.1016/j.epsl.2017.01.028).

Record type: Article

Abstract

The late Pliocene/early Pleistocene intensification of Northern Hemisphere Glaciation (iNHG) represents the most recent major tipping point in Earth's climate history. In the equatorial Pacific, the iNHG has been suggested to mark the transition from a warm Pliocene climate state, in which the Pacific warm pool was greatly expanded relative to today giving rise to a surface ocean temperature field akin to modern El Niño conditions, to a climate state with strong upwelling in the east of the basin and stronger zonal temperature gradients. Here we examine this transition by presenting new high-resolution (∼800 yr) planktic foraminiferal Mg/Ca- and δ18δ18O-based sea-surface temperature (SST) and salinity (SSS; based on δ18Oδ18O residuals [δ18Oivc-swδ18Oivc-sw]) records from Eastern Equatorial Pacific (EEP) Ocean Drilling Program Site 849 spanning ∼2.75–2.4 Ma. Our study interval contains the first large-amplitude (∼1‰ in benthic δ18δ18O) early Pleistocene glacial–interglacial cycles (Marine Isotope Stages 100–96) representing the culmination of iNHG. In this study we investigate west-to-east equatorial Pacific SST and SSS gradients. We find that the zonal SST gradient increased by ∼1.5 °C from ∼2.75 to ∼2.4 Ma through EEP cooling. No glacial–interglacial pattern is seen in this gradient. On the other hand, we document obliquity-paced oscillations in the δ18Oivc-swδ18Oivc-sw (SSS) gradient. We hypothesize that these oscillations originated from a response to a glacial southward and interglacial northward migration of the Intertropical Convergence Zone over the EEP.

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More information

Accepted/In Press date: 23 January 2017
Published date: 1 April 2017
Organisations: Ocean and Earth Science, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 407193
URI: http://eprints.soton.ac.uk/id/eprint/407193
ISSN: 0012-821X
PURE UUID: 8c584bdf-83d9-4ceb-9c71-d28b78b5f515
ORCID for Paul A. Wilson: ORCID iD orcid.org/0000-0001-6425-8906

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Date deposited: 01 Apr 2017 01:05
Last modified: 31 May 2022 01:36

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Contributors

Author: Kim A. Jakob
Author: Clara T. Bolton
Author: Paul A. Wilson ORCID iD
Author: André Bahr
Author: Jörg Pross
Author: Jens Fiebig
Author: Karsten Kähler
Author: Oliver Friedrich

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