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Penultimate deglacial warming across the Mediterranean Sea revealed by clumped isotopes in foraminifera

Penultimate deglacial warming across the Mediterranean Sea revealed by clumped isotopes in foraminifera
Penultimate deglacial warming across the Mediterranean Sea revealed by clumped isotopes in foraminifera
The variability of seawater temperature through time is a critical measure of climate change, yet its reconstruction remains problematic in many regions. Mg/Ca and oxygen isotope (δ18OC) measurements in foraminiferal carbonate shells can be combined to reconstruct seawater temperature and δ18O (δ18OSW). The latter is a measure of changes in local hydrology (e.g., precipitation/evaporation, freshwater inputs) and global ice volume. But diagenetic processes may affect foraminiferal Mg/Ca. This restricts its potential in many places, including the Mediterranean Sea, a strategic region for deciphering global climate and sea-level changes. High alkalinity/salinity conditions especially bias Mg/Ca temperatures in the eastern Mediterranean (eMed). Here we advance the understanding of both western Mediterranean (wMed) and eMed hydrographic variability through the penultimate glacial termination (TII) and last interglacial, by applying the clumped isotope (Δ47) paleothermometer to planktic foraminifera with a novel data-processing approach. Results suggest that North Atlantic cooling during Heinrich stadial 11 (HS11) affected surface-water temperatures much more in the wMed (during winter/spring) than in the eMed (during summer). The method’s paired Δ47 and δ18OC data also portray δ18OSW. These records reveal a clear HS11 freshwater signal, which attenuated toward the eMed, and also that last interglacial surface warming in the eMed was strongly amplified by water-column stratification during the deposition of the organic-rich (sapropel) interval known as S5.
2045-2322
Rodríguez-Sanz, L.
96063bec-9dd9-4386-89f6-f6c9d13a8bc4
Bernasconi, S. M.
d60685c9-9440-45e1-a27e-9e9e1c872082
Marino, G.
d2f4dc29-b2e7-4cf0-8abd-6fd855bfab81
Heslop, D.
11d150c2-95ed-4403-be36-005242abe22c
Müller, I. A.
1a289230-b001-4e81-ad33-ea761a7b298a
Fernandez, A.
8bd2d1b1-9831-46fd-9042-92455ef7bb3e
Grant, K.M.
4258644a-ecaa-48cc-baad-739ced4bd945
Rohling, E. J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Rodríguez-Sanz, L.
96063bec-9dd9-4386-89f6-f6c9d13a8bc4
Bernasconi, S. M.
d60685c9-9440-45e1-a27e-9e9e1c872082
Marino, G.
d2f4dc29-b2e7-4cf0-8abd-6fd855bfab81
Heslop, D.
11d150c2-95ed-4403-be36-005242abe22c
Müller, I. A.
1a289230-b001-4e81-ad33-ea761a7b298a
Fernandez, A.
8bd2d1b1-9831-46fd-9042-92455ef7bb3e
Grant, K.M.
4258644a-ecaa-48cc-baad-739ced4bd945
Rohling, E. J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685

Rodríguez-Sanz, L., Bernasconi, S. M., Marino, G., Heslop, D., Müller, I. A., Fernandez, A., Grant, K.M. and Rohling, E. J. (2017) Penultimate deglacial warming across the Mediterranean Sea revealed by clumped isotopes in foraminifera. Scientific Reports, 7 (1), [16572]. (doi:10.1038/s41598-017-16528-6).

Record type: Article

Abstract

The variability of seawater temperature through time is a critical measure of climate change, yet its reconstruction remains problematic in many regions. Mg/Ca and oxygen isotope (δ18OC) measurements in foraminiferal carbonate shells can be combined to reconstruct seawater temperature and δ18O (δ18OSW). The latter is a measure of changes in local hydrology (e.g., precipitation/evaporation, freshwater inputs) and global ice volume. But diagenetic processes may affect foraminiferal Mg/Ca. This restricts its potential in many places, including the Mediterranean Sea, a strategic region for deciphering global climate and sea-level changes. High alkalinity/salinity conditions especially bias Mg/Ca temperatures in the eastern Mediterranean (eMed). Here we advance the understanding of both western Mediterranean (wMed) and eMed hydrographic variability through the penultimate glacial termination (TII) and last interglacial, by applying the clumped isotope (Δ47) paleothermometer to planktic foraminifera with a novel data-processing approach. Results suggest that North Atlantic cooling during Heinrich stadial 11 (HS11) affected surface-water temperatures much more in the wMed (during winter/spring) than in the eMed (during summer). The method’s paired Δ47 and δ18OC data also portray δ18OSW. These records reveal a clear HS11 freshwater signal, which attenuated toward the eMed, and also that last interglacial surface warming in the eMed was strongly amplified by water-column stratification during the deposition of the organic-rich (sapropel) interval known as S5.

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Accepted/In Press date: 13 November 2017
e-pub ahead of print date: 29 November 2017
Published date: 1 December 2017

Identifiers

Local EPrints ID: 416245
URI: http://eprints.soton.ac.uk/id/eprint/416245
ISSN: 2045-2322
PURE UUID: dab4171e-a122-413b-b66c-2a0d6ceeef13
ORCID for E. J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 11 Dec 2017 17:30
Last modified: 09 Jan 2022 02:46

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Contributors

Author: L. Rodríguez-Sanz
Author: S. M. Bernasconi
Author: G. Marino
Author: D. Heslop
Author: I. A. Müller
Author: A. Fernandez
Author: K.M. Grant
Author: E. J. Rohling ORCID iD

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