Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean
Ice core records demonstrate a glacial–interglacial atmospheric CO2 increase of ~ 100 ppm, while 14C calibration efforts document a strong decrease in atmospheric 14C concentration during this period. A calculated transfer of ~ 530 Gt of 14C-depleted carbon is required to produce the deglacial coeva...
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fttriple:oai:gotriple.eu:Yj2n6W3H9_3PdYIUTsusI 2023-05-15T16:39:26+02:00 Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean Sarnthein, M. Schneider, B. Grootes, P. M. 2018-09-27 https://doi.org/10.5194/cp-9-2595-2013 https://cp.copernicus.org/articles/9/2595/2013/ en eng Copernicus Publications doi:10.5194/cp-9-2595-2013 10670/1.h1o14r 1814-9324 1814-9332 https://cp.copernicus.org/articles/9/2595/2013/ undefined Geographica Helvetica - geography eISSN: 1814-9332 envir geo Text https://vocabularies.coar-repositories.org/resource_types/c_18cf/ Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2018 fttriple https://doi.org/10.5194/cp-9-2595-2013 2023-01-22T17:52:09Z Ice core records demonstrate a glacial–interglacial atmospheric CO2 increase of ~ 100 ppm, while 14C calibration efforts document a strong decrease in atmospheric 14C concentration during this period. A calculated transfer of ~ 530 Gt of 14C-depleted carbon is required to produce the deglacial coeval rise of carbon in the atmosphere and terrestrial biosphere. This amount is usually ascribed to oceanic carbon release, although the actual mechanisms remained elusive, since an adequately old and carbon-enriched deep-ocean reservoir seemed unlikely. Here we present a new, though still fragmentary, ocean-wide Δ14C data set showing that during the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS-1) the maximum 14C age difference between ocean deep waters and the atmosphere exceeded the modern values by up to 1500 14C yr, in the extreme reaching 5100 14C yr. Below 2000 m depth the 14C ventilation age of modern ocean waters is directly linked to the concentration of dissolved inorganic carbon (DIC). We propose as a working hypothesis that the modern regression of DIC vs. Δ14C also applies for LGM times, which implies that a mean LGM aging of ~ 600 14C yr corresponded to a global rise of ~ 85–115 μmol DIC kg−1 in the deep ocean. Thus, the prolonged residence time of ocean deep waters may indeed have made it possible to absorb an additional ~ 730–980 Gt DIC, one third of which possibly originated from intermediate waters. We also infer that LGM deep-water O2 dropped to suboxic values of < 10 μmol kg−1 in the Atlantic sector of the Southern Ocean, possibly also in the subpolar North Pacific. The deglacial transfer of the extra-aged, deep-ocean carbon to the atmosphere via the dynamic ocean–atmosphere carbon exchange would be sufficient to account for two trends observed, (1) for the increase in atmospheric CO2 and (2) for the 190‰ drop in atmospheric Δ14C during the so-called HS-1 "Mystery Interval", when atmospheric 14C production rates were largely constant. Article in Journal/Newspaper ice core Southern Ocean Unknown Pacific Southern Ocean Climate of the Past 9 6 2595 2614 |
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envir geo Sarnthein, M. Schneider, B. Grootes, P. M. Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
topic_facet |
envir geo |
description |
Ice core records demonstrate a glacial–interglacial atmospheric CO2 increase of ~ 100 ppm, while 14C calibration efforts document a strong decrease in atmospheric 14C concentration during this period. A calculated transfer of ~ 530 Gt of 14C-depleted carbon is required to produce the deglacial coeval rise of carbon in the atmosphere and terrestrial biosphere. This amount is usually ascribed to oceanic carbon release, although the actual mechanisms remained elusive, since an adequately old and carbon-enriched deep-ocean reservoir seemed unlikely. Here we present a new, though still fragmentary, ocean-wide Δ14C data set showing that during the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS-1) the maximum 14C age difference between ocean deep waters and the atmosphere exceeded the modern values by up to 1500 14C yr, in the extreme reaching 5100 14C yr. Below 2000 m depth the 14C ventilation age of modern ocean waters is directly linked to the concentration of dissolved inorganic carbon (DIC). We propose as a working hypothesis that the modern regression of DIC vs. Δ14C also applies for LGM times, which implies that a mean LGM aging of ~ 600 14C yr corresponded to a global rise of ~ 85–115 μmol DIC kg−1 in the deep ocean. Thus, the prolonged residence time of ocean deep waters may indeed have made it possible to absorb an additional ~ 730–980 Gt DIC, one third of which possibly originated from intermediate waters. We also infer that LGM deep-water O2 dropped to suboxic values of < 10 μmol kg−1 in the Atlantic sector of the Southern Ocean, possibly also in the subpolar North Pacific. The deglacial transfer of the extra-aged, deep-ocean carbon to the atmosphere via the dynamic ocean–atmosphere carbon exchange would be sufficient to account for two trends observed, (1) for the increase in atmospheric CO2 and (2) for the 190‰ drop in atmospheric Δ14C during the so-called HS-1 "Mystery Interval", when atmospheric 14C production rates were largely constant. |
format |
Article in Journal/Newspaper |
author |
Sarnthein, M. Schneider, B. Grootes, P. M. |
author_facet |
Sarnthein, M. Schneider, B. Grootes, P. M. |
author_sort |
Sarnthein, M. |
title |
Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
title_short |
Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
title_full |
Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
title_fullStr |
Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
title_full_unstemmed |
Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean |
title_sort |
peak glacial 14c ventilation ages suggest major draw-down of carbon into the abyssal ocean |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-9-2595-2013 https://cp.copernicus.org/articles/9/2595/2013/ |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
ice core Southern Ocean |
genre_facet |
ice core Southern Ocean |
op_source |
Geographica Helvetica - geography eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-9-2595-2013 10670/1.h1o14r 1814-9324 1814-9332 https://cp.copernicus.org/articles/9/2595/2013/ |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/cp-9-2595-2013 |
container_title |
Climate of the Past |
container_volume |
9 |
container_issue |
6 |
container_start_page |
2595 |
op_container_end_page |
2614 |
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1766029783424040960 |