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Research Project: Oceans 2025 Theme 1:Ocean circulation, sea level and climate change

  Theme 1:Ocean circulation, sea level and climate change Sub Theme 1: Ocean dynamics in a changing climate

Abstract: The research will investigate recent and ancestral variability of the northern limb of the MOC from the north-east Atlantic to northern Norway, to determine whether the changes in salinity and temperature of the last two decades have any historical precedence and to investigate the long-term geological activity of the MOC over at least one glacial-interglacial cycle. SAMS will also investigate the suitability of a new monitoring section that will support and augment existing long term observations exchange and connectivity across the Iceland-Scotland Ridge.

Keywords:
Hydrographic transect, Ancestral MOC, Sediment archives

  Research Project Information
Runtime: 2007-04-01 until 2012-03-31
Contact: T. Sherwin
Project coordination: T. Shimmield
Scientific coordination: T. Shimmield
Scientific staff: F. Cottier, J. Howe, N. Hughes, T. Sherwin, T. Shimmield
Technical staff: S. McKinlay; M. Harvey; T. Brand; C. Haidon
Cooperation partner(s): Proudman Oceanographic Laboratory; National Oceanography Centre


JCR1
At present, palaeoceanographic records of North Atlantic Overturning remain geographically dispersed across the northwestern North Atlantic (McCave, 2002, Weltje and Prins, 2003). By sampling in the regions of established oceanographic time-series in the northeastern North Atlantic it is proposed to develop a stronger link between the modern instrumental and the palaeo-ancestral record of the MOC. By examining records from diverse depositional environments across established hydrographic sections (e.g. Ellett line – across the UK shelf, the Rockall basin and bank) it is anticipated that records can be obtained showing variability within the MOC across a wide geographic area. These records will provide resolution over a number of temporal scales, (e.g. high-resolution Holocene-age records from the shelf, with pre-Holocene, lower-resolution records from the deep-sea). This region of the mid-high latitude northeast Atlantic can contain geological records that are critical to our understanding of global climatic change and its linkages to global thermohaline circulation. At timescales of millennia and longer, the marine sedimentary record can provide high-resolution records of climatic variability over at least the last 18,000 years (Cortijo et al., 2000). Utilising the high sedimentation rates (3-100cms/1000 years) of bottom-current enhanced deposition found across the transect, Holocene climatic events such as the Little Ice Age and the Medieval Warming Period (RCC events of Mayewski et al., 2004) could become detectable and, perhaps ultimately traceable between basins allowing the chronology and influence of RCC events to be resolved. This ‘time-slice’ approach relies heavily on the use of established palaeo-proxy data such as sediment grain size for bottom-current variability, 18O and 13C, Mg/Ca, Sr/Ca for temperature and salinity of bottom waters and the rigorous use of 14C and 210Pb to constrain the chronology of the cores. To relate the palaeo-record with the instrumental datasets of MOC will use short undisturbed sediment cores sampling to establish the modern benthic conditions at, or near the sea floor. Palaeo-proxies such as Cd/Ca, Ba and carbon isotopic composition will be used to reconstruct past productivity and nutrient availability. Pre-existing core records, notably those from the Norwegian Margin, the Faeroe-Shetland Channel and the Rockall Trough can also be examined or re-examined negating the need for expensive sampling cruises.




SAMS
Scottish Marine Institute
Oban, Argyll, PA37 1QA

T: 01631 559000
F: 01631 559001
E: info@sams.ac.uk

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