Abstract91 – University of Copenhagen

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Centre for Ice and Climate > Publications > Scientific papers > Abstracts > Abstract91

High-resolution analyses of an early Holocene climate event may imply decreased solar forcing as an important climate trigger 

Geological Society of America, vol. 29, no. 12, p. 1107-1110, 2001 

S. Björk
Department of Quaternary Geology, Lund University, Tornav. 13, SE-223 63 Lund, Sweden.
R. Muscheler
Swiss Federal Institute for Environmental Science and Technology (EAWAG), Ueberlandstrasse 133, Postfach 611, CH-8600 Duebendorf, Switzerland.
B. Kromer
Heidelberg Academy of Science, INF 229, D-69120 Heidelberg, Germany.
C.S. Andresen
Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark.
J. Heinemeier
AMS Laboratory, Institute for Physics and Astronomy, DK-8000 Aarhus C, Denmark.
S.J. Johnsen
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
D. Conley
Department of Marine Ecology, Danmarks Miljøundersøgelser (DMU), P.O. Box 358, DK-4000 Roskilde, Denmark.
N. Koç
Norwegian Polar Institute, Polar Environmental Centre, N-9296 Tromsø, Norway.
M. Spurk
Universität Hohenheim, Institute für Botanik, D-70593 Stuttgart, Germany.
S. Veski
Tallinn Technical University, Institute of Geology, Estonia pst. 7, 10143 Tallinn, Estonia.

ABSTRACT.
Early Holocene lacustrine, tree-ring, ice-core, and marine records reveal that the Northern Hemisphere underwent a short cooling event at 10,300 calender yr B.P. (9100 14C yr B.P.). The records were compared on a common high-resolution time scale and show that the event lasted less than 200 yr, with a cooling peak of 50 yr, and the event coincides with a distinct Holocene thermohaline disturbance recognized in the North Atlantic Ocean. In spite of well-known freshwater forcings at the time of the event, the negligible difference between the modeled D14C record, based on the GISP2 (Greenland Ice Sheet Project 2) 10Be data, and the measured values, does not allow for detectable D14C changes related to global ocean ventilation. We can, however, show that the onset of the cooling coincides with the onset of one of the largest Holocene 10Be flux peaks. This finding may imply that the climate system is more sensitive to solar-related changes than previously thought and that such changes may be an important underlying mechanism for sub-Milankovitch climate variability.