Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean

Sarnthein, Michael, Schneider, Birgit and Grootes, P. M. (2013) Peak glacial 14C ventilation ages suggest major draw-down of carbon into the abyssal ocean Climate of the Past, 9 (6). pp. 2595-2614. DOI 10.5194/cp-9-2595-2013.

[img]
Preview
Text
cp-9-2595-2013.pdf - Published Version
Available under License Creative Commons Attribution.

Download (10Mb) | Preview
[img]
Preview
Text
cp-9-2595-2013-supplement.pdf - Supplemental Material
Available under License Creative Commons Attribution.

Download (969Kb) | Preview

Supplementary data:

Abstract

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

Document Type: Article
Research affiliation: Kiel University > Faculty of Mathematics and Natural Sciences > Institute of Geosciences
OceanRep > SFB 754
OceanRep > SFB 754 > A1
Refereed: Yes
DOI etc.: 10.5194/cp-9-2595-2013
ISSN: 1814-9332
Projects: SFB754, BIOACID
Date Deposited: 08 Aug 2014 11:07
Last Modified: 09 Jan 2017 12:42
URI: http://oceanrep.geomar.de/id/eprint/25422

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...