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| Sadatzki, Henrik. |
| The Arctic sea ice cover is in fast transition. Resolving past sea ice fluctuations and its link with abrupt climate change might be key for a better understanding of yet unknown climatic consequences of future Arctic sea ice loss. The last glacial period was marked by recurring abrupt climate changes, referred to as Dansgaard–Oeschger (D–O) climate cycles. These D–O climate cycles and in particular the associated abrupt warming transitions by up to 15°C over Greenland happening within years or decades might have been linked to shifts in sea ice cover in the Nordic Seas. This PhD thesis aims at resolving and constraining the largely unknown millennialscale sea ice variability in the Nordic Seas and its pivotal role for abrupt climate changes during the D–O... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00505/61699/65667.pdf |
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| Berben, Sarah M.p.; Dokken, Trond M.; Abbott, Peter M.; Cook, Eliza; Sadatzki, Henrik; Simon, Margit H; Jansen, Eystein. |
| Understanding the dynamics that drove past abrupt climate changes, such as the Dansgaard-Oeschger (DO) events, depends on combined proxy evidence from disparate archives. To identify leads, lags and synchronicity between different climate system components, independent and robust chronologies are required. Cryptotephrochronology is a key geochronological tool as cryptotephra horizons can act as isochrons linking disparate and/or distant records. Here, we investigated marine sediment core MD99-2284 from the Norwegian Sea to look for previously identified Greenland ice core cryptotephra horizons and define time-parallel markers between the archives. We explored potential secondary transport and depositional mechanisms that could hamper the isochronous... |
| Tipo: Text |
Palavras-chave: Quaternary; Paleoclimatology; Paleoceanography; North Atlantic; Sedimentology; Marine cores; Ice cores; Cryptotephrochronology; DO-Events; Synchronization. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00622/73391/72606.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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| Sadatzki, Henrik; Maffezzoli, Niccolò; Dokken, Trond M.; Simon, Margit H; Berben, Sarah M. P.; Fahl, Kirsten; Kjær, Helle A.; Spolaor, Andrea; Stein, Ruediger; Vallelonga, Paul; Vinther, Bo M.; Jansen, Eystein. |
| Constraining the past sea ice variability in the Nordic Seas is critical for a comprehensive understanding of the abrupt Dansgaard-Oeschger (D-O) climate changes during the last glacial. Here we present unprecedentedly detailed sea ice proxy evidence from two Norwegian Sea sediment cores and an East Greenland ice core to resolve and constrain sea ice variations during four D-O events between 32 and 41 ka. Our independent sea ice records consistently reveal a millennial-scale variability and threshold response between an extensive seasonal sea ice cover in the Nordic Seas during cold stadials and reduced seasonal sea ice conditions during warmer interstadials. They document substantial and rapid sea ice reductions that may have happened within 250 y or... |
| Tipo: Text |
Palavras-chave: Sea ice; Nordic Seas; Dansgaard-Oeschger events; Abrupt climate change. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00659/77066/78374.pdf |
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