Synchronized Terrestrial-Atmospheric Deglacial Records Around the North Atlantic 

Science, Vol. 274, p. 1155-1160, 1996 

S. Björck and T.L. Rasmussen
Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
B. Kromer
Heidelberg Academy of Science, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany.
S. Johnsen and C.U. Hammer
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
O. Bennike
GEUS, Thoravej 8, DK-2400 Copenhagen, Denmark.
D. Hammarlund, G. Lemdahl and B. Wohlfarth
Department of Quaternary Geology, Lund University, Tornavägen 13, S-22363 Lund, Sweden. G. Possnert
Tandem Laboratory, Uppsala University, Box 533, S-75121 Uppsala, Sweden.
M. Spurk
Institut für Botanik, Universität Hohenheim, Garbenstrasse 30, D-70593 Stuttgart, Germany.

ABSTRACT.
On the basis of synchronization of three carbon-14 (¹⁴C)-dated lacustrine sequences from Sweden with tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 ± 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising Δ¹⁴C values, is evident in all records and indicates an ocean ventilation change. This cooling is similar to earlier deglacial coolings, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor, although the Younger Dryas may have begun as an anomalous meltwater event.