Southern Ocean contribution to both steps in deglacial atmospheric CO2 rise

Abstract The transfer of vast amounts of carbon from a deep oceanic reservoir to the atmosphere is considered to be a dominant driver of the deglacial rise in atmospheric CO 2 . Paleoceanographic reconstructions reveal evidence for the existence of CO 2 -rich waters in the mid to deep Southern Ocean...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Ronge, Thomas A., Frische, Matthias, Fietzke, Jan, Stephens, Alyssa L., Bostock, Helen, Tiedemann, Ralf
Other Authors: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Deutsche Forschungsgemeinschaft, GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, International Ocean Discovery Program, University of Queensland, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI)
Format: Article in Journal/Newspaper
Language:English
Published: Springer Science and Business Media LLC 2021
Subjects:
Multidisciplinary
Antarctic
New Zealand
Pacific
Southern Ocean
Antarc*
Online Access:http://dx.doi.org/10.1038/s41598-021-01657-w
https://www.nature.com/articles/s41598-021-01657-w.pdf
https://www.nature.com/articles/s41598-021-01657-w
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Summary:Abstract The transfer of vast amounts of carbon from a deep oceanic reservoir to the atmosphere is considered to be a dominant driver of the deglacial rise in atmospheric CO 2 . Paleoceanographic reconstructions reveal evidence for the existence of CO 2 -rich waters in the mid to deep Southern Ocean. These water masses ventilate to the atmosphere south of the Polar Front, releasing CO 2 prior to the formation and subduction of intermediate-waters. Changes in the amount of CO 2 in the sea water directly affect the oceanic carbon chemistry system. Here we present B/Ca ratios, a proxy for delta carbonate ion concentrations Δ[CO 3 2− ], and stable isotopes (δ 13 C) from benthic foraminifera from a sediment core bathed in Antarctic Intermediate Water (AAIW), offshore New Zealand in the Southwest Pacific. We find two transient intervals of rising [CO 3 2− ] and δ 13 C that that are consistent with the release of CO 2 via the Southern Ocean. These intervals coincide with the two pulses in rising atmospheric CO 2 at ~ 17.5–14.3 ka and 12.9–11.1 ka. Our results lend support for the release of sequestered CO 2 from the deep ocean to surface and atmospheric reservoirs during the last deglaciation, although further work is required to pin down the detailed carbon transfer pathways.

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