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| Levi, Camille; Labeyrie, Laurent; Bassinot, Franck; Guichard, Francois; Cortijo, Elsa; Waelbroeck, Claire; Caillon, Nicolas; Duprat, Josette; De Garidel-thoron, Thibault; Elderfield, Harry. |
| Sea surface temperature and oxygen isotopic records from two well-dated Indian Ocean cores covering the last deglaciation show the occurrence of two periods of increased salinity along the route of warm surface water transport from the Indian to the Atlantic Ocean, one between 18 and 14.5 ka and the other during the Younger Dryas. Our results imply that during these periods, salt accumulated in the tropical Atlantic, creating favorable conditions for an abrupt resumption of the thermohaline circulation and abrupt northern hemisphere warming. Furthermore, we suggest that the observed pattern of millennial climate variability during the last glacial and deglaciation resulted from the interaction between the relatively slow rhythm of expansion and decay of... |
| Tipo: Text |
Palavras-chave: Rapid climate changes; Low-latitude hydrological cycle; Last deglaciation. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34611/32960.pdf |
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| Cleroux, Caroline; Cortijo, Elsa; Anand, Pallavi; Labeyrie, Laurent; Bassinot, Franck; Caillon, Nicolas; Duplessy, Jean-claude. |
| [1] Reliable temperature estimates from both surface and subsurface ocean waters are needed to reconstruct past upper water column temperature gradients and past oceanic heat content. This work examines the relationships between trace element ratios in fossil shells and seawater temperature for surface-dwelling foraminifera species, Globigerinoides ruber (white) and Globigerina bulloides, and deep-dwelling species, Globorotalia inflata, Globorotalia truncatulinoides (dextral and sinistral) and Pulleniatina obliquiloculata. Mg/Ca and Sr/Ca ratios in shells picked in 29 modern core tops from the North Atlantic Ocean are calibrated using calculated isotopic temperatures. Mg/Ca ratios on G. ruber and G. bulloides agree with published data and relationships.... |
| Tipo: Text |
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| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00237/34806/33325.pdf |
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| Cleroux, Caroline; Debret, Maxime; Cortijo, Elsa; Duplessy, Jean-claude; Dewilde, Fabien; Reijmer, John; Massei, Nicolas. |
| This study presents high-resolution foraminiferal-based sea surface temperature, sea surface salinity and upper water column stratification reconstructions off Cape Hatteras, a region sensitive to atmospheric and thermohaline circulation changes associated with the Gulf Stream. We focus on the last 10,000 years (10 ka) to study the surface hydrology changes under our current climate conditions and discuss the centennial to millennial time scale variability. We observed opposite evolutions between the conditions off Cape Hatteras and those south of Iceland, known today for the North Atlantic Oscillation pattern. We interpret the temperature and salinity changes in both regions as co-variation of activities of the subtropical and subpolar gyres. Around 8.3... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37681/36613.pdf |
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| Paterne, Martine; Kallel, Nejib; Labeyrie, Laurent; Vautravers, Maryline J.; Duplessy, Jean-claude; Rossignol-strick, Martine; Cortijo, Elsa; Arnold, Maurice; Fontugne, Michel. |
| The Mediterranean Sea hydrology at the time of the Heinrich formation in the North Atlantic Ocean was analyzed by comparing sea surface temperatures (SSTs) and oxygen isotope composition of seawater (delta w) changes during the past 75 kyr in two marine cores. These were compared to the palynological variations derived in the Mediterranean Sea core. During the last glacial the two oceanic SST records show similar and synchronous patterns, with several long-term cooling periods, ending by abrupt SST increases. At the time of the Heinrich events, cold SSTs and low salinity prevailed in the Mediterranean Sea. The freshwater budget was similar to the modern one, permitting the presence of a mixed forest on the Mediterranean borderlands. The post-Heinrich... |
| Tipo: Text |
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| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35050/36799.pdf |
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| Eynaud, Frederique; Malaize, Bruno; Zaragosi, Sebastien; De Vernal, Anne; Scourse, James; Pujol, Claude; Cortijo, Elsa; Grousset, Francis E.; Penaud, Aurelie; Toucanne, Samuel; Turon, Jean-louis; Auffret, Gerard. |
| During the late Quaternary, both external and internal forcings have driven major climatic shifts from glacial to interglacial conditions. Nonlinear climatic steps characterized the transitions leading to these extrema, with intermediate excursions particularly well expressed in the dynamics of the Northern Hemisphere cryosphere. Here we document the impact of these dynamics on the north-eastern North Atlantic Ocean, focussing on the 35-10 ka interval. Sea-surface salinities have been reconstructed quantitatively based on two independent methods from core MD95-2002, recovered from the northern Bay of Biscay adjacent to the axis of the Manche paleoriver outlet and thus in connection with proximal European ice sheets and glaciers. Quantitative... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00086/19762/20100.pdf |
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| Paillard, Didier; Cortijo, Elsa. |
| With a simplified two-dimensionnal Atlantic Ocean model, we investigate the response of the deep ocean circulation to reconstructed sea surface salinity and temperature used as surface boundary conditions at two time slices: just before and during Heinrich event 4. In contrast to previous studies, we do not make any assumption about freshwater input. Our model results suggest that the recorded estimations of surface hydrological changes during an Heinrich event are able to induce a drastic slowdown, or even a collapse, of the overall Atlantic thermohaline circulation. This is, to some extent, consistent with records of the deep sea ventilation at these times. |
| Tipo: Text |
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| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00239/35045/36806.pdf |
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