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AmocCC - Constraining the relationship between climate, ACC flow intensity and Antarctic Meridional Overturning Circulation across the last glacial cycle

Applicant Jaccard Samuel
Number 163003
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geochemistry
Start/End 01.01.2016 - 30.09.2019
Approved amount 462'993.00
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All Disciplines (2)

Discipline
Geochemistry
Oceanography

Keywords (4)

ACC; climate; CO2; ocean circulation

Lay Summary (French)

Lead
L’océan Austral se comporte comme un gigantesque poumon qui absorbe et rejette, au gré de variations saisonnières et interannuelles, d'importantes quantités de dioxyde de carbone (CO2). Avec un ratio largement en faveur de l’absorption puisque cette vaste étendue d’eau, représentant 25% de la surface océanique globale, participe pour 40% à la séquestration océanique des rejets anthropiques de carbone. Cela dit, certains modèles climatiques indiquent que ce puits pourrait s'atténuer dans un futur proche en conséquence du réchauffement climatique. Il en résulterait qu'une plus grande proportion du carbone émis par les activités anthropiques se retrouverait dans l'atmosphère, une conséquence qui serait dramatique pour l’équilibre climatique de la Terre.
Lay summary

Ce projet de recherche propose d’explorer les causes et conséquences inhérentes au changement de circulation océanique dans l’océan Austral au cours du dernier cycle glaciaire. L’objectif principal de ce projet est de déterminer dans quelle mesure l’océan Austral affecte l’évolution de la pression partielle de CO2 dans l’atmosphère au cours du dernier âge glaciaire. Spécifiquement, nous proposons de reconstruire l’évolution temporelle du courant circumpolaire Antarctique (ACC) sur la base d’une série d’archives sédimentaires marines formant un transect méridional dans le sud de l’océan Indien. Nous proposons également d’étudier la variabilité de la circulation océanique profonde durant le dernier interglaciaire, afin de mieux contraindre les modèles climatiques.

 

Direct link to Lay Summary Last update: 06.01.2016

Responsible applicant and co-applicants

Employees

Publications

Publication
Constraining the Variability of the Atlantic Meridional Overturning Circulation During the Holocene
Lippold Jörg, Pöppelmeier Frerk, Süfke Finn, Gutjahr Marcus, Goepfert Tyler J., Blaser Patrick, Friedrich Oliver, Link Jasmin M., Wacker Lukas, Rheinberger Stefan, Jaccard Samuel L. (2019), Constraining the Variability of the Atlantic Meridional Overturning Circulation During the Holocene, in Geophysical Research Letters, 46(20), 11338-11346.
Mechanisms of millennial-scale atmospheric CO2 change in numerical model simulations
Gottschalk Julia, Battaglia Gianna, Fischer Hubertus, Frölicher Thomas L., Jaccard Samuel L., Jeltsch-Thömmes Aurich, Joos Fortunat, Köhler Peter, Meissner Katrin J., Menviel Laurie, Nehrbass-Ahles Christoph, Schmitt Jochen, Schmittner Andreas, Skinner Luke C., Stocker Thomas F. (2019), Mechanisms of millennial-scale atmospheric CO2 change in numerical model simulations, in Quaternary Science Reviews, 220, 30-74.
Past Carbonate Preservation Events in the Deep Southeast Atlantic Ocean (Cape Basin) and Their Implications for Atlantic Overturning Dynamics and Marine Carbon Cycling
Gottschalk Julia, Hodell David A., Skinner Luke C., Crowhurst Simon J., Jaccard Samuel L., Charles Christopher (2018), Past Carbonate Preservation Events in the Deep Southeast Atlantic Ocean (Cape Basin) and Their Implications for Atlantic Overturning Dynamics and Marine Carbon Cycling, in Paleoceanography and Paleoclimatology, 33(6), 643-663.
RADIOCARBON MEASUREMENTS OF SMALL-SIZE FORAMINIFERAL SAMPLES WITH THE MINI CARBON DATING SYSTEM (MICADAS) AT THE UNIVERSITY OF BERN: IMPLICATIONS FOR PALEOCLIMATE RECONSTRUCTIONS
Gottschalk Julia, Szidat Sönke, Michel Elisabeth, Mazaud Alain, Salazar Gary, Battaglia Michael, Lippold Jörg, Jaccard Samuel (2018), RADIOCARBON MEASUREMENTS OF SMALL-SIZE FORAMINIFERAL SAMPLES WITH THE MINI CARBON DATING SYSTEM (MICADAS) AT THE UNIVERSITY OF BERN: IMPLICATIONS FOR PALEOCLIMATE RECONSTRUCTIONS, in Radiocarbon, 60(2), 469-491.
Calibration of the carbon isotope composition (δ13C) of benthic foraminifera
Schmittner Andreas, Bostock Helen C., Cartapanis Olivier, Curry William B., Filippson Helena L., Galbraith Eric D., Gottschalk Julia, Herguera Juan Carlos, Hoogakker Babette, Jaccard Samuel L., Lisiecki Lorraine E., Lund David C., Martinez-Mendez Gema, Lynch-Stigelitz Jean, Mackensen Andreas, Michel Elisabeth, Mix Alan C., Oppo Delia W., Repschläger Janne, Sikes Elisabeth L., Spero Howard J., Waelbroeck Clarie, Peterson Carlye D. (2017), Calibration of the carbon isotope composition (δ13C) of benthic foraminifera, in Paleoceanography, 32(6), 512-530.
Constraining the Variability of the Atlantic Meridional Overturning Circulation During the Holocene
LippoldJörg, PöpplemeierFrerk, SüfkeFinn, GutjahrMarcus, GoepfertTyler, BlaserPatrick, FriedrichOliver, LinkJasmin, WackerLukas, RheinbergerStefan, JaccardSamuel, Constraining the Variability of the Atlantic Meridional Overturning Circulation During the Holocene, in Geophysical Research Letters, 46.

Scientific events



Self-organised

Title Date Place

Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Nacht der Forschung, UniBe German-speaking Switzerland 2017

Associated projects

Number Title Start Funding scheme
192361 Constraining the sensitivity of land/cryosphere-Southern Ocean interactions to climate change across the last glacial cycle 01.03.2021 Project funding (Div. I-III)
144811 SeaO2 - Past changes in Southern Ocean overturning circulation - implications for the partitioning of carbon and oxygen between the ocean and the atmosphere 01.10.2013 SNSF Professorships

Abstract

This research proposal aims at investigating the causes and effects of changes in Southern Ocean circulation over the last glacial cycle (i.e. the last 150 kyrs). In particular, we seek to better understand the role of the Southern Ocean in modulating past atmospheric carbon dioxide (CO2) changes, a question of central importance to predicting the future of CO2 and climate in the context of human perturbation. The climate sensitivities of the circum-Antarctic ocean circulation are critical in their own right, as the Southern Ocean critically affects global heat transport, albedo, continental ice dynamics, and marine biological resources. Our goal here is to characterize the climate thresholds and feedbacks that might emerge in a warmer world. One aspect of this work will deal with the central importance of the vertical stability in the polar oceans as a driver of atmospheric CO2 changes. Observations and climate simulations highlight the critical role played by the Antarctic Circumpolar Current (ACC) and its sensitivity to the latitudinal position- and intensity of the Southern Hemisphere westerlies in controlling the long-term evolution of the oceanic anthropogenic carbon sink, through its leverage on the Southern Ocean overturning circulation. The past changes in Southern Ocean circulation may have much to tell us about its future. Climate models of anthropogenic warming predict a future increase in the stratification of the polar regions, with consequences for the biological productivity and the fluxes of energy and CO2. Yet, the accumulated paleoclimate data from circum-Antarctic sedimentary archives argue for the opposite response, with stronger stratification in cold climates, not warm ones.Specifically, we propose to - (A) investigate the temporal evolution of the ACC flow velocity during the last ice age in two sediment cores influenced by the current in the SW Indian Ocean following a multi-proxy approach. The two sediment cores are located close to the modern location of the Subantarctic (SAF)- and Antarctic Polar fronts (APF), respectively. As such they have the potential to record latitudinal changes in the maximum flow speed, providing insights on the strength and latitudinal position of the westerlies through time; (B) to examine the temporal evolution of deep ocean ventilation using a foraminifera-based multi-proxy approach across Termination II and the subsequent transition from peak interglacial conditions (MIS 5e) to the last ice age (MIS4) in two cores collected from the Atlantic- and Indian sectors of the Southern Ocean, respectively. These observations will help constraining the physical mechanisms allowing the climate system to transition into ice ages.
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