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| Sha, Longbin; Jiang, Hui; Seidenkrantz, Marit-solveig; Muscheler, Raimund; Zhang, Xu; Knudsen, Mads Faurschou; Olsen, Jesper; Knudsen, Karen Luise; Zhang, Weiguo. |
| Arctic sea ice represents an important component of the climate system, and the present reduction of sea ice in the Arctic is of major concern. Despite its importance, little is known about past changes in sea-ice cover and the underlying forcing mechanisms. Here, we use diatom assemblages from a marine sediment core collected from the West Greenland shelf to reconstruct changes in sea-ice cover over the last millennium. The proxy-based reconstruction demonstrates a generally strong link between changes in sea-ice cover and solar variability during the last millennium. Weaker (or stronger) solar forcing may result in the increase (or decrease) in sea-ice cover west of Greenland. In addition, model simulations show that variations in solar activity not only... |
| Tipo: Text |
Palavras-chave: Sea-ice variability; Solar activity; West Greenland; Last millennium. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53291/54134.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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| 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... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00511/62284/66502.pdf |
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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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| Abelmann, Andrea; Gersonde, Rainer; Knorr, Gregor; Zhang, Xu; Chapligin, Bernhard; Maier, Edith; Esper, Oliver; Friedrichsen, Hans; Lohmann, Gerrit; Meyer, Hanno; Tiedemann, Ralf. |
| Reduced surface-deep ocean exchange and enhanced nutrient consumption by phytoplankton in the Southern Ocean have been linked to lower glacial atmospheric CO2. However, identification of the biological and physical conditions involved and the related processes remains incomplete. Here we specify Southern Ocean surface-subsurface contrasts using a new tool, the combined oxygen and silicon isotope measurement of diatom and radiolarian opal, in combination with numerical simulations. Our data do not indicate a permanent glacial halocline related to melt water from icebergs. Corroborated by numerical simulations, we find that glacial surface stratification was variable and linked to seasonal sea-ice changes. During glacial spring-summer, the mixed layer was... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00497/60842/64285.pdf |
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