International Geologiical Congress - Oslo 2008

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AAA-10 Arctic palaeoclimate and its extremes

 

Palaeoclimate of the last two millennia in northern Norwegian fjords

 

Lindsay Wilson, University of Tromsoe (Norway)
Morten Hald, University of Tromsoe (Norway)
Katrine Husum, University of Tromsoe (Norway)
 

 

Instrumental records have highlighted a warming trend over the last few decades in the high northern latitudes. Climate models suggest that over the next century an increased temperature in polar regions may be twice the global mean. This study utilises benthic foraminifera to reconstruct marine bottom water temperatures and water mass behaviour from a series of cores from the northern Norwegian continental margin.
The results are presented from four cores from shelf sea (Andfjorden) and fjord (Malangen, Vestfjorden and Sagfjorden) settings. Radiocarbon and Pb210 dating demonstrate a series of high-resolution (annual to decadal) timescales spanning approximately the last 500 to 2000 years. At present, these sites are strongly influenced by the inflow of warm Atlantic water by the Norwegian Coastal Current (NCC).
Temperatures reconstructions are based on benthic foraminiferal oxygen isotope measurements. The results indicate an overall warming trend of approximately 2.5 o C through the 1500 year record. In addition, the well-documented cooling period equating to the "Little Ice Age" is evident between ca. 1690-1800. Most notably a series of highly fluctuating temperatures are observed over the last century.
Statistical comparisons are made to modern instrumental temperature data from approximately the same locations. Of particular interest is the onset of the rapid warming towards the end of the 20th century on a scale of 1-2 o C. In addition, microfaunal species composition data will be presented from Sagfjorden, indicating the changing influence of the NCC waters within the inner fjord environment over the last millennia.

 

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