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| Stein, Ruediger; Hefter, Jens; Gruetzner, Jens; Voelker, Antje; Naafs, B. David A.. |
| A reconstruction of Milankovitch to millennial-scale variability of sea surface temperature (SST) and sea surface productivity in the Pleistocene midlatitude North Atlantic Ocean (marine isotope stage (MIS) 16-9) and its relationship to ice sheet instability was carried out on sediments from Integrated Ocean Drilling Program (IODP) Site U1313. This reconstruction is based on alkenone and n-alkane concentrations, U-37(K)' index, total organic carbon (TOC) and carbonate contents, X-ray diffraction data, magnetic susceptibility, and accumulation rates. Increased input of ice-rafted debris occurred during MIS 16, 12, and 10, characterized by high concentrations of dolomite, quartz, and feldspars and elevated accumulation rates of terrigenous matter. Minimum... |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32941/31424.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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| Hoff, Ulrike; Rasmussen, Tine L.; Stein, Ruediger; Ezat, Mohamed M.; Fahl, Kirsten. |
| In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial-scale climatic events (Dansgaard/Oeschger events) using the sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the southeast Norwegian Sea. We demonstrate that expansion and retreat of sea ice varies consistently in pace with the rapid climate changes 90 kyr ago to present. Sea ice retreats abruptly at the start of warm interstadials, but spreads rapidly during cooling phases of the interstadials and becomes near perennial and perennial during cold... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00496/60722/65265.pdf |
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| Stein, Ruediger; Fahl, Kirsten; Gierz, Paul; Niessen, Frank; Lohmann, Gerrit. |
| Coinciding with global warming, Arctic sea ice has rapidly decreased during the last four decades and climate scenarios suggest that sea ice may completely disappear during summer within the next about 50-100 years. Here we produce Arctic sea ice biomarker proxy records for the penultimate glacial (Marine Isotope Stage 6) and the subsequent last interglacial (Marine Isotope Stage 5e). The latter is a time interval when the high latitudes were significantly warmer than today. We document that even under such warmer climate conditions, sea ice existed in the central Arctic Ocean during summer, whereas sea ice was significantly reduced along the Barents Sea continental margin influenced by Atlantic Water inflow. Our proxy reconstruction of the last... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00495/60712/65326.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... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59606/62620.pdf |
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