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| Galaasen, Eirik Vinje; Ninnemann, Ulysses S.; Kessler, Augustin; Irvalı, Nil; Rosenthal, Yair; Tjiputra, Jerry; Bouttes, Nathaëlle; Roche, Didier M.; Kleiven, Helga (kikki) F.; Hodell, David A.. |
| Disrupting North Atlantic Deep Water (NADW) ventilation is a key concern in climate projections. We use (sub)centennially resolved bottom water δ13C records that span the interglacials of the last 0.5 million years to assess the frequency of and the climatic backgrounds capable of triggering large NADW reductions. Episodes of reduced NADW in the deep Atlantic, similar in magnitude to glacial events, have been relatively common and occasionally long-lasting features of interglacials. NADW reductions were triggered across the range of recent interglacial climate backgrounds, which demonstrates that catastrophic freshwater outburst floods were not a prerequisite for large perturbations. Our results argue that large NADW disruptions are more easily achieved... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00663/77524/79329.pdf |
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| Lougheed, Bryan C.; Metcalfe, Brett; Ninnemann, Ulysses S.; Wacker, Lukas. |
| Late-glacial palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid changes in ocean chemistry. Unfortunately, only a small proportion of the ocean floor with sufficiently high sediment accumulation rate (SAR) is suitable for such reconstructions using the long-standing age-depth model approach. We employ ultra-small radiocarbon (C-14) dating on single microscopic foraminifera to demonstrate that the long-standing age-depth model method conceals large age uncertainties caused by post-depositional sediment mixing, meaning that existing studies may underestimate total geochronological error. We find that the age-depth distribution of our C-14-dated single foraminifera is in good agreement with existing... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00497/60820/65117.pdf |
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| Irvali, Nil; Ninnemann, Ulysses S.; Kleiven, Helga (kikki) F.; Galaasen, Eirik V.; Morley, Audrey; Rosenthal, Yair. |
| High-resolution lithic and sea surface climate records are used to portray the progression of North Atlantic climate, hydrography, and Greenland Ice Sheet (GIS) activity through the peak of Marine Isotope Stage (MIS) 5e into the last glacial inception. We use Eirik Drift sediment core MD03-2664 (57°26.34′N, 48°36.35′W), recovered south of Greenland, strategically located to monitor fluctuations in GIS extent and iceberg calving events. Our results show that a significant amount of ice-rafted debris (IRD) was present during the early MIS 5e, until gradually tapering off by 122 kyr BP due to a diminishing GIS. Sea surface temperatures (SSTs) in the northern subpolar gyre reached peak values early in MIS 5e coinciding with peak insolation. Regional cooling... |
| Tipo: Text |
Palavras-chave: Eirik drift; Greenland Ice Sheet; North Atlantic; Last interglacial; Glacial inception; Multi-proxy. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00349/46009/45681.pdf |
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| Irvali, Nil; Ninnemann, Ulysses S.; Galaasen, Eirik V.; Rosenthal, Yair; Kroon, Dick; Oppo, Delia W.; Kleiven, Helga F.; Darling, Kate F.; Kissel, Catherine. |
| At the peak of the previous interglacial period, North Atlantic and subpolar climate shared many features in common with projections of our future climate, including warmer-than-present conditions and a diminished Greenland Ice Sheet (GIS). Here we portray changes in North Atlantic hydrography linked with Greenland climate during Marine Isotope Stage (MIS) 5e using (sub)centennially sampled records of planktonic foraminiferal isotopes and assemblage counts and ice-rafted debris counts, as well as modern analog technique and Mg/Ca-based paleothermometry. We use the core MD03-2664 recovered from a high accumulation rate site (similar to 34 cm/kyr) on the Eirik sediment drift (57 degrees 26.34'N, 48 degrees 36.35'W). The results indicate that surface waters... |
| Tipo: Text |
Palavras-chave: Eirik Drift; MIS 5e; North Atlantic; Last interglacial; Multiproxy. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00139/25046/23154.pdf |
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