Atlantic Meridional Overturning Circulation and δ13C Variability During the Last Interglacial

A. Kessler; N. Bouttes; D. M. Roche; U. S. Ninnemann; E. V. Galaasen; J. Tjiputra

doi:10.1029/2019PA003818

Atlantic Meridional Overturning Circulation and δ¹³C Variability During the Last Interglacial

A. Kessler^*, N. Bouttes, D. M. Roche, U. S. Ninnemann, E. V. Galaasen, J. Tjiputra

^*Corresponding author for this work

Earth Sciences

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

Abstract

The Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ¹³C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of (Formula presented.) and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial-scale variations in the interior (Formula presented.) of the North Atlantic similar in timescale and amplitude to changes resolved by high-resolution reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed (Formula presented.) of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ¹³C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.

Original language	English
Article number	e2019PA003818
Pages (from-to)	1-17
Number of pages	17
Journal	Paleoceanography and Paleoclimatology
Volume	35
Issue number	5
Early online date	23 Apr 2020
DOIs	https://doi.org/10.1029/2019PA003818
Publication status	Published - 1 May 2020

Funding

We thank the two anonymous referees for their positive and constructive comments, which helped to clarify the manuscript. We also thank the Editor Stephen Barker for the time he dedicated in processing our manuscript and his additional feedback. This work was supported by the Research Council of Norway funded project THRESHOLDS (254964) and ORGANIC (239965) and Bjerknes Centre for Climate Research project BIGCHANGE. We acknowledge the Norwegian Metacenter for Computational Science and Storage Infrastructure (Notur/Norstore) projects nn1002k and ns1002k for providing the computing and storing resources essential for this study. The authors declare no conflict of interest.The model data are available on the Norwegian Research Data Archive server (https://doi.org/10.11582/2019.00037 Kessler,).

Funders	Funder number
Bjerknes Centre for Climate Research
ORGANIC	239965
Norges forskningsråd	254964

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1029/2019PA003818

Persistent URL (handle)

Persistent link

Cite this

@article{2d8b0e73bf674f4a9e33205d84bf8c6b,

title = "Atlantic Meridional Overturning Circulation and δ13C Variability During the Last Interglacial",

abstract = "The Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ13C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of (Formula presented.) and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial-scale variations in the interior (Formula presented.) of the North Atlantic similar in timescale and amplitude to changes resolved by high-resolution reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed (Formula presented.) of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ13C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.",

author = "A. Kessler and N. Bouttes and Roche, {D. M.} and Ninnemann, {U. S.} and Galaasen, {E. V.} and J. Tjiputra",

year = "2020",

month = may,

day = "1",

doi = "10.1029/2019PA003818",

language = "English",

volume = "35",

pages = "1--17",

journal = "Paleoceanography and Paleoclimatology",

issn = "2572-4517",

publisher = "John Wiley and Sons Inc.",

number = "5",

}

TY - JOUR

T1 - Atlantic Meridional Overturning Circulation and δ13C Variability During the Last Interglacial

AU - Kessler, A.

AU - Bouttes, N.

AU - Roche, D. M.

AU - Ninnemann, U. S.

AU - Galaasen, E. V.

AU - Tjiputra, J.

PY - 2020/5/1

Y1 - 2020/5/1

N2 - The Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ13C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of (Formula presented.) and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial-scale variations in the interior (Formula presented.) of the North Atlantic similar in timescale and amplitude to changes resolved by high-resolution reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed (Formula presented.) of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ13C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.

AB - The Atlantic Meridional Overturning Circulation (AMOC) is thought to be relatively vigorous and stable during Interglacial periods on multimillennial (equilibrium) timescales. However, recent proxy (δ13C benthic) reconstructions suggest that higher frequency variability in deep water circulation may have been common during some interglacial periods, including the Last Interglacial (LIG, 130–115 ka). The origin of these isotope variations and their implications for past AMOC remain poorly understood. Using iLOVECLIM, an Earth system model of intermediate complexity (EMIC) allowing the computation of (Formula presented.) and direct comparison to proxy reconstructions, we perform a transient experiment of the LIG (125–115 ka) forced only by boundary conditions of greenhouse gases and orbital forcings. The model simulates large centennial-scale variations in the interior (Formula presented.) of the North Atlantic similar in timescale and amplitude to changes resolved by high-resolution reconstructions from the LIG. In the model, these variations are caused by changes in the relative influence of North Atlantic Deep Water (NADW) and southern source water (SSW) and are closely linked to large (∼50%) changes in AMOC strength provoked by saline input and associated deep convection areas south of Greenland. We identify regions within the subpolar North Atlantic with different sensitivity and response to changes in preformed (Formula presented.) of NADW and to changes in NADW versus SSW influence, which is useful for proxy record interpretation. This could explain the relatively large δ13C gradient (∼0.4%0) observed at ∼3 km water depth in the subpolar North Atlantic at the inception of the last glacial.

UR - http://www.scopus.com/inward/record.url?scp=85085382947&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85085382947&partnerID=8YFLogxK

U2 - 10.1029/2019PA003818

DO - 10.1029/2019PA003818

M3 - Article

AN - SCOPUS:85085382947

SN - 2572-4517

VL - 35

SP - 1

EP - 17

JO - Paleoceanography and Paleoclimatology

JF - Paleoceanography and Paleoclimatology

IS - 5

M1 - e2019PA003818

ER -