From full glacial to current interglacial conditions: a high-resolution record of sea ice variability in Fram Strait
Arctic Ocean sea ice cover is a crucial element within the global climate system. Reconstructions of its spatial and temporal variability in the geological past provide important information on oceanic-atmospheric feedback mechanisms and further support the assessment of natural (vs. anthropogenic-i...
| Main Authors: | , |
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| Format: | Conference Object |
| Language: | unknown |
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2014
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/35685/ https://hdl.handle.net/10013/epic.43609 |
| Summary: | Arctic Ocean sea ice cover is a crucial element within the global climate system. Reconstructions of its spatial and temporal variability in the geological past provide important information on oceanic-atmospheric feedback mechanisms and further support the assessment of natural (vs. anthropogenic-induced) climate change. The Fram Strait - the only deep-water passage connecting the Arctic and the Atlantic Ocean - is an ideal target area for palaeo sea ice studies since changes in the export of Arctic sea ice into the Atlantic may be recorded and effectively preserved within Fram Strait sediments. Here we present a continuous and high-resolution sea ice record obtained from a sediment core from the western continental margin of Svalbard that experienced exceptional high sedimentation rates (20 - 100 cm/ka) throughout the past 30 ka BP. The reconstruction of sea ice conditions is based upon organic geochemical analyses focussing on the sea ice biomarker IP25 (Belt & Müller, 2013) and - for a comprehensive and more detailed evaluation of the sea surface conditions - phytoplankton derived biomarkers (following Müller et al., 2011, 2012). The late glacial period (30 ka - 20 ka BP), is characterised by recurrent advances and retreats of sea ice at the core site. In contrast to the widely acknowledged notion of a continuous advection of warm Atlantic water along the eastern corridor of the Nordic Seas, we attribute these sea ice fluctuations to rather pulse-like North Atlantic water intrusions during this critical time interval for Northern Hemisphere Ice Sheet growth. Permanent sea ice cover dominated only at the end of the Last Glacial Maximum and became abruptly reduced at 18 ka BP - just prior (or contributing) to the weakening of the Atlantic Meridional Overturning Circulation during Heinrich Event 1 (McManus et al., 2004). A second and short-lived maximum in sea ice coverage prevails during the Younger Dryas until the onset of the Holocene when sea ice became significantly reduced and sea surface temperatures ... |
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