M. Hald et R. Aspeli, RAPID CLIMATIC SHIFTS OF THE NORTHERN NORWEGIAN SEA DURING THE LAST DEGLACIATION AND THE HOLOCENE, Boreas, 26(1), 1997, pp. 15-28
High resolution cores from the upper continental slope, northern Norwe
gian Sea, document rapid climatic fluctuations during the latest degla
ciation and the Holocene. Based on down-core analysis of planktic and
benthic foraminifera, stable oxygen and carbon isotopes, carbonate and
organic carbon and radiocarbon dating, the following evolution is pro
posed: sea-ice cover broke up, the surface ocean warmed and an in situ
benthic foraminiferal fauna was established at 12 500 BP. The Younger
Dryas was characterized by reduced sedimentaion and foraminiferal pro
duction, due to surface ocean cooling. At the end of the Younger Dryas
there were major shifts in both surface and bottom water conditions.
The surface ocean warmed to temperatures similar to modern levels with
in <100 years, reaching a maximum at about 9200 BP when foraminiferal
production was high. A benthic foraminiferal assemblage indicative of
bottom water conditions similar to present conditions was established
at 10 000 BP. This was followed by a gradual decline in nutrients or a
n increase in ventilation of the bottom water throughout the Holocene.
A gradual surface ocean cooling of c. 2 degrees C ended around 6500 B
P followed by a second warming that culminated at 2000 BP. The warming
at the end of the Younger Dryas and the succeeding older Holocene tem
perature maximum correlate to a June insolation maximum in the norther
n hemisphere. In addition, fluctuating surface temperatures in the Hol
ocene may be driven by variations in inflow of Atlantic Water.