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| Zheng, Xufeng; Kao, Shuhji; Chen, Zhong; Menviel, Laurie; Chen, Han; Du, Yan; Wan, Shiming; Yan, Hong; Liu, Zhonghui; Zheng, Liwei; Wang, Shuhong; Li, Dawei; Zhang, Xu. |
| Deepwater circulation plays a central role in global climate. Compared with the Atlantic, the Pacific deepwater circulation's history remains unclear. The Luzon overflow, a branch of the North Pacific deep water, determines the ventilation rate of the South China Sea (SCS) basin. Sedimentary magnetic properties in the SCS reflect millennial-scale fluctuations in deep current intensity and orientation. The data suggest a slightly stronger current at the Last Glacial Maximum compared to the Holocene. But, the most striking increase in deep current occurred during Heinrich stadial 1 (H1) and to a lesser extent during the Younger Dryas (YD). Results of a transient deglacial experiment suggest that the northeastern current strengthening at the entrance of the... |
| Tipo: Text |
Palavras-chave: South China Sea; Deep current; Anisotropy of magnetic susceptibility; Heinrich 1; Atlantic-Pacific seesaw. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53224/54800.pdf |
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| Menviel, Laurie; Capron, Emilie; Govin, Aline; Dutton, Andrea; Tarasov, Lev; Abe-ouchi, Ayako; Drysdale, Russell; Gibbard, Philip; Gregoire, Lauren; He, Feng; Ivanovic, Ruza; Kageyama, Masa; Kawamura, Kenji; Landais, Amaelle; Otto-bliesner, Bette L.; Oyabu, Ikumi; Tzedakis, Polychronis; Wolff, Eric; Zhang, Xu. |
| The penultimate deglaciation (~ 138–128 thousand years before present, hereafter ka) is the transition from the penultimate glacial maximum to the Last Interglacial (LIG, ~ 129–116 ka). The LIG stands out as one of the warmest interglacials of the last 800 ka, with high-latitude temperature warmer than today and global sea level likely higher by at least 6 meters. The LIG therefore receives ever-growing attention, in particular to identify mechanisms and feedbacks responsible for such regional warmth that is comparable to that expected before 2100. Considering the transient nature of the Earth system, the LIG climate and ice-sheets evolution were certainly influenced by the changes occurring during the penultimate deglaciation. It is thus important to... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00491/60241/63638.pdf |
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| Bagniewski, Witold; Meissner, Katrin J.; Menviel, Laurie; Brennan, Catherine E.. |
| We perform idealized experiments of a Heinrich Stadial using an oxygen-isotope-enabled Earth System Climate Model. Our results compare relatively well with the planktic and benthic delta O-18 records of Heinrich Stadials 1 and 4. We find that changes in surface delta O-18(c) can be equally attributed to the "temperature effect" due to fractionation during calcification; the "circulation and climate effect" due to changes in circulation, precipitation, and evaporation; and the "meltwater effect" due to the addition and subsequent advection of depleted fresh water from continental ice sheets. In contrast, the meltwater effect and circulation and climate effect have only a small impact on benthic delta O-18(c) during the cessation of the Atlantic Meridional... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46253/46085.pdf |
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| Margari, Vasiliki; Skinner, Luke C.; Menviel, Laurie; Capron, Emilie; Rhodes, Rachael H.; Mleneck-vautravers, Maryline J.; Ezat, Mohamed M.; Martrat, Belen; Grimalt, Joan O.; Hodell, David A.; Tzedakis, Polychronis C.. |
| The abrupt nature of warming events recorded in Greenland ice-cores during the last glacial has generated much debate over their underlying mechanisms. Here, we present joint marine and terrestrial analyses from the Portuguese Margin, showing a succession of cold stadials and warm interstadials over the interval 35–57 ka. Heinrich stadials 4 and 5 contain considerable structure, with a short transitional phase leading to an interval of maximum cooling and aridity, followed by slowly increasing sea-surface temperatures and moisture availability. A climate model experiment reproduces the changes in western Iberia during the final part of Heinrich stadial 4 as a result of the gradual recovery of the Atlantic meridional overturning circulation. What emerges is... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00643/75476/76313.pdf |
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| Stockhecke, Mona; Timmermann, Axel; Kipfer, Rolf; Haug, Gerald H.; Kwiecien, Ola; Friedrich, Tobias; Menviel, Laurie; Litt, Thomas; Pickarski, Nadine; Anselmetti, Flavio S.. |
| Millennial to orbital-scale rainfall changes in the Mediterranean region and corresponding variations in vegetation patterns were the result of large-scale atmospheric reorganizations. In spite of recent efforts to reconstruct this variability using a range of proxy archives, the underlying physical mechanisms have remained elusive. Through the analysis of a new high-resolution sedimentary section from Lake Van (Turkey) along with climate modeling experiments, we identify massive droughts in the Eastern Mediterranean for the past four glacial cycles, which have a pervasive link with known intervals of enhanced North Atlantic glacial iceberg calving, weaker Atlantic Meridional Overturning Circulation and Dansgaard-Oeschger cold conditions. On orbital... |
| Tipo: Text |
Palavras-chave: Dansgaard-Oeschger variability; Mediterranean droughts; Milankovitch cycles; Lake Van; ICDP PALEOVAN. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53271/54623.pdf |
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| Menviel, Laurie; Capron, Emilie; Govin, Aline; Dutton, Andrea; Tarasov, Lev; Abe-ouchi, Ayako; Drysdale, Russell N.; Gibbard, Philip L.; Gregoire, Lauren; He, Feng; Ivanovic, Ruza F.; Kageyama, Masa; Kawamura, Kenji; Landais, Amaelle; Otto-bliesner, Bette L.; Oyabu, Ikumi; Tzedakis, Polychronis C.; Wolff, Eric; Zhang, Xu. |
| The penultimate deglaciation (PDG, ∼138–128 thousand years before present, hereafter ka) is the transition from the penultimate glacial maximum (PGM) to the Last Interglacial (LIG, ∼129–116 ka). The LIG stands out as one of the warmest interglacials of the last 800 000 years (hereafter kyr), with high-latitude temperature warmer than today and global sea level likely higher by at least 6 m. Considering the transient nature of the Earth system, the LIG climate and ice-sheet evolution were certainly influenced by the changes occurring during the penultimate deglaciation. It is thus important to investigate, with coupled atmosphere–ocean general circulation models (AOGCMs), the climate and environmental response to the large changes in boundary conditions... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00511/62284/66502.pdf |
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| Bagniewski, Witold; Meissner, Katrin J.; Menviel, Laurie. |
| We present the first transient simulations of Marine Isotope Stage 3 (MIS 3) performed with an oxygen isotope-enabled climate model. Our simulations span several Dansgaard-Oeschger cycles and three Heinrich stadials and are directly compared with oxygen isotope records from 13 sediment and 2 ice cores. Our results are consistent with a 30-50% weakening of the Atlantic Meridional Overturning Circulation during Dansgaard-Oeschger stadials and a complete shutdown during Heinrich stadials. We find that the simulated delta O-18 anomalies differ significantly between Heinrich stadials and non-Heinrich stadials. This difference is mainly due to different responses in ocean circulation, and therefore climate, impacting oceanic delta O-18, while the volume of... |
| Tipo: Text |
Palavras-chave: MIS3; Model-data comparison; Heinrich events; Dansgaard-Oeschger cycles; Delta O-18; AMOC. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53180/55067.pdf |
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| Sadatzki, Henrik; Dokken, Trond M.; Berben, Sarah M. P.; Muschitiello, Francesco; Stein, Ruediger; Fahl, Kirsten; Menviel, Laurie; Timmermann, Axel; Jansen, Eystein. |
| The last glacial period was marked by pronounced millennial-scale variability in ocean circulation and global climate. Shifts in sea ice cover within the Nordic Seas are believed to have amplified the glacial climate variability in northern high latitudes and contributed to abrupt, high-amplitude temperature changes over Greenland. We present unprecedented empirical evidence that resolves the nature, timing, and role of sea ice fluctuations for abrupt ocean and climate change 32 to 40 thousand years ago, using biomarker sea ice reconstructions from the southern Norwegian Sea. Our results document that initial sea ice reductions at the core site preceded the major reinvigoration of convective deep-water formation in the Nordic Seas and abrupt Greenland... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59606/62620.pdf |
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