Southwest Atlantic water mass evolution during the last deglaciation
The rise in atmospheric CO₂ during Heinrich Stadial 1 (HS1; 14.5–17.5 kyr B.P.) may have been driven by the release of carbon from the abyssal ocean. Model simulations suggest that wind-driven upwelling in the Southern Ocean can liberate ¹³C-depleted carbon from the abyss, causing atmospheric CO₂ to...
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ftoregonstate:ir.library.oregonstate.edu:b27741291 2023-11-12T04:26:38+01:00 Southwest Atlantic water mass evolution during the last deglaciation Lund, D. C. Tessin, A. C. Hoffman, J. L. Schmittner, A. https://ir.library.oregonstate.edu/concern/articles/b27741291 English [eng] eng John Wiley & Sons Ltd. https://ir.library.oregonstate.edu/concern/articles/b27741291 Copyright Not Evaluated Article ftoregonstate 2023-10-22T16:47:20Z The rise in atmospheric CO₂ during Heinrich Stadial 1 (HS1; 14.5–17.5 kyr B.P.) may have been driven by the release of carbon from the abyssal ocean. Model simulations suggest that wind-driven upwelling in the Southern Ocean can liberate ¹³C-depleted carbon from the abyss, causing atmospheric CO₂ to increase and the δ¹³C of CO₂ to decrease. One prediction of the Southern Ocean hypothesis is that water mass tracers in the deep South Atlantic should register a circulation response early in the deglaciation. Here we test this idea using a depth transect of 12 cores from the Brazil Margin. We show that records below 2300 m remained ¹³C-depleted until 15 kyr B.P. or later, indicating that the abyssal South Atlantic was an unlikely source of light carbon to the atmosphere during HS1. Benthic δ¹⁸O results are consistent with abyssal South Atlantic isolation until 15 kyr B.P., in contrast to shallower sites. The depth dependent timing of the δ¹⁸O signal suggests that correcting δ¹⁸O for ice volume is problematic on glacial terminations. New data from 2700 to 3000 m show that the deep SW Atlantic was isotopically distinct from the abyss during HS1. As a result, we find that mid-depth δ¹³C minima were most likely driven by an abrupt drop in δ¹³C of northern component water. Low δ¹³C at the Brazil Margin also coincided with an ~80‰ decrease in Δ¹⁴C. Our results are consistent with a weakening of the Atlantic meridional overturning circulation and point toward a northern hemisphere trigger for the initial rise in atmospheric CO₂ during HS1. This is the publisher’s final pdf. The published article is published by John Wiley & Sons Ltd. and copyrighted by American Geophysical Union. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/journal/10.1002/%28ISSN%291944-9186/ Keywords: carbon dioxide, deglaciation, South Atlantic, stable isotopes Article in Journal/Newspaper Southern Ocean ScholarsArchive@OSU (Oregon State University) Southern Ocean |
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English |
description |
The rise in atmospheric CO₂ during Heinrich Stadial 1 (HS1; 14.5–17.5 kyr B.P.) may have been driven by the release of carbon from the abyssal ocean. Model simulations suggest that wind-driven upwelling in the Southern Ocean can liberate ¹³C-depleted carbon from the abyss, causing atmospheric CO₂ to increase and the δ¹³C of CO₂ to decrease. One prediction of the Southern Ocean hypothesis is that water mass tracers in the deep South Atlantic should register a circulation response early in the deglaciation. Here we test this idea using a depth transect of 12 cores from the Brazil Margin. We show that records below 2300 m remained ¹³C-depleted until 15 kyr B.P. or later, indicating that the abyssal South Atlantic was an unlikely source of light carbon to the atmosphere during HS1. Benthic δ¹⁸O results are consistent with abyssal South Atlantic isolation until 15 kyr B.P., in contrast to shallower sites. The depth dependent timing of the δ¹⁸O signal suggests that correcting δ¹⁸O for ice volume is problematic on glacial terminations. New data from 2700 to 3000 m show that the deep SW Atlantic was isotopically distinct from the abyss during HS1. As a result, we find that mid-depth δ¹³C minima were most likely driven by an abrupt drop in δ¹³C of northern component water. Low δ¹³C at the Brazil Margin also coincided with an ~80‰ decrease in Δ¹⁴C. Our results are consistent with a weakening of the Atlantic meridional overturning circulation and point toward a northern hemisphere trigger for the initial rise in atmospheric CO₂ during HS1. This is the publisher’s final pdf. The published article is published by John Wiley & Sons Ltd. and copyrighted by American Geophysical Union. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/journal/10.1002/%28ISSN%291944-9186/ Keywords: carbon dioxide, deglaciation, South Atlantic, stable isotopes |
format |
Article in Journal/Newspaper |
author |
Lund, D. C. Tessin, A. C. Hoffman, J. L. Schmittner, A. |
spellingShingle |
Lund, D. C. Tessin, A. C. Hoffman, J. L. Schmittner, A. Southwest Atlantic water mass evolution during the last deglaciation |
author_facet |
Lund, D. C. Tessin, A. C. Hoffman, J. L. Schmittner, A. |
author_sort |
Lund, D. C. |
title |
Southwest Atlantic water mass evolution during the last deglaciation |
title_short |
Southwest Atlantic water mass evolution during the last deglaciation |
title_full |
Southwest Atlantic water mass evolution during the last deglaciation |
title_fullStr |
Southwest Atlantic water mass evolution during the last deglaciation |
title_full_unstemmed |
Southwest Atlantic water mass evolution during the last deglaciation |
title_sort |
southwest atlantic water mass evolution during the last deglaciation |
publisher |
John Wiley & Sons Ltd. |
url |
https://ir.library.oregonstate.edu/concern/articles/b27741291 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
https://ir.library.oregonstate.edu/concern/articles/b27741291 |
op_rights |
Copyright Not Evaluated |
_version_ |
1782340546529853440 |