International Geologiical Congress - Oslo 2008

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AAA-10 Arctic palaeoclimate and its extremes

 

Planktonic foraminiferal fauna in the Fram Strait during the last millennium

 

Katarzyna Zamelczyk, University of Tromsų (Norway)
Katrine Husum, University of Tromsų (Norway)
Morten Hald, University of Tromsų (Norway)
 

 

The present climate in the Arctic shows sings of rapid change with decreasing sea ice cover and increasing temperature of Atlantic Water. The implications of this warming are highly uncertain, and high-resolution proxy records that stretches further back than instrumental records are needed in order to evaluate implications of past warm periods. During the last millennium temperature reconstructions from the northern Hemisphere display both warmer and colder periods than at present. Warm conditions at the beginning of the last millennium, sometimes called the 'Medieval Warm Period' end before 1300 AD. It is followed by a gradual cooling, interrupted by relatively short, warm periods. The cold period, often referred to as 'the Little Ice Age', ends in the 19th century before a noticeable warming during the 20th century. However, little is known about the last millennium so far north as the Fram Strait. The Fram Strait is also an important area for these investigations because it represents the end member of the warm and saline Atlantic Water of the North Atlantic Current, before it submerges as an intermediate layer into the Arctic Ocean. In addition, cold polar water and sea ice enters the Fram Strait from the Arctic Ocean with the East Greenland Current resulting in strong environmental gradients at the surface in this area. Two sediment cores from the middle and western Fram Strait have been investigated with regard to planktonic foraminifera, and AMS 14C dates Core JM06-WP-16 MC is located in the middle of the Fram Strait close to the Arctic Front separating Arctic and Atlantic water masses. Core JM06-WP-04-MC is located on West Spitsbergen slope under the West Spitsbergen Current transporting Atlantic Water. Preliminary results show strong dominance of the polar species Neogloboquadrina pachyderma left coiled and a pronounced fluctuation of the subpolar species Turborotalita quinqeloba. The faunal variations indicate century scale variations in the oceanic fronts of the area.

 

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