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| Yu, J.; Menviel, L.; Jin, Z. D.; Thornalley, D. J. R.; Barker, S.; Marino, G.; Rohling, E. J.; Cai, Y.; Zhang, F.; Wang, X.; Dai, Y.; Chen, P.; Broecker, W. S.. |
| Atmospheric CO2 concentrations declined markedly about 70,000 years ago, when the Earth's climate descended into the last glaciation. Much of the carbon removed from the atmosphere has been suspected to have entered the deep oceans, but evidence for increased carbon storage remains elusive. Here we use the B/Ca ratios of benthic foraminifera from several sites across the Atlantic Ocean to reconstruct changes in the carbonate ion concentration and hence the carbon inventory of the deep Atlantic across this transition. We find that deep Atlantic carbonate ion concentration declined by around 25 mu mol kg(-1) between similar to 80,000 and 65,000 years ago. This drop implies that the deep Atlantic carbon inventory increased by at least 50 Gt around the same... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53257/83375.pdf |
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| Thornalley, D. J. R.; Blaschek, M.; Davies, F. J.; Praetorius, S.; Oppo, D. W.; Mcmanus, J. F.; Hall, I. R.; Kleiven, H.; Renssen, H.; Mccave, I. N.. |
| The overflow of deep water from the Nordic seas into the North Atlantic plays a critical role in global ocean circulation and climate. Approximately half of this overflow occurs via the Iceland-Scotland (I-S) overflow, yet the history of its strength throughout the Holocene (similar to 0-11 700 yr ago, ka) is poorly constrained, with previous studies presenting apparently contradictory evidence regarding its long-term variability. Here, we provide a comprehensive reconstruction of I-S overflow strength throughout the Holocene using sediment grain size data from a depth transect of 13 cores from the Iceland Basin. Our data are consistent with the hypothesis that the main axis of the I-S overflow on the Iceland slope was shallower during the early Holocene,... |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37571/35836.pdf |
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| Hoogakker, B. A. A.; Thornalley, D. J. R.; Barker, S.. |
| Glacial-interglacial changes in bottom water oxygen concentrations [O-2] in the deep northeast Atlantic have been linked to decreased ventilation relating to changes in ocean circulation and the biological pump (Hoogakker et al., 2015). In this paper we discuss seawater [O-2] changes in relation to millennial climate oscillations in the North Atlantic over the last glacial cycle, using bottom water [O-2] reconstructions from 2 cores: (1) MD95-2042 from the deep northeast Atlantic (Hoogakker et al., 2015) and (2) ODP (Ocean Drilling Program) Site 1055 from the intermediate north-west Atlantic. The deep northeast Atlantic core MD95-2042 shows decreased bottom water [O-2] during millennial-scale cool events, with lowest bottom water [O-2] of 170, 144, and 166... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00353/46416/46157.pdf |
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