Evidence for Obliquity Forcing of Glacial Termination II
R. N. Drysdale,1,*
J. C. Hellstrom,2
G. Zanchetta,3,4,5
A. E. Fallick,6
M. F. Sánchez Goñi,7
I. Couchoud,1
J. McDonald,1
R. Maas,2
G. Lohmann,8
I. Isola4
Variations in the intensity of high-latitude Northern Hemisphere
summer insolation, driven largely by precession of the equinoxes,
are widely thought to control the timing of Late Pleistocene
glacial terminations. However, recently it has been suggested
that changes in Earth’s obliquity may be a more important
mechanism. We present a new speleothem-based North Atlantic
marine chronology that shows that the penultimate glacial termination
(Termination II) commenced 141,000 ± 2500 years before
the present, too early to be explained by Northern Hemisphere
summer insolation but consistent with changes in Earth’s
obliquity. Our record reveals that Terminations I and II are
separated by three obliquity cycles and that they started at
near-identical obliquity phases.
2 School of Earth Sciences, University of Melbourne, Parkville, Victoria 2010, Australia.
3 Department of Earth Sciences, University of Pisa, Pisa 56100, Italy.
4 Istituto Nazionale di Geofisica e Vulcanologia, via della Fagiola, Pisa 56126, Italy.
5 IGG-CNR, Via Moruzzi, 1 56100 Pisa, Italy.
6 Scottish Universities Environmental Research Centre, East Kilbride G75 0GF, UK.
7 EPHE, UMR CNRS 5805 EPOC, Université Bordeaux 1, 33405 Talence, France.
8 Alfred Wegener Institute for Polar and Marine Research, Bussestrasse 24, D-27570 Bremerhaven, Germany.
* To whom correspondence should be addressed. E-mail: russell.drysdale{at}newcastle.edu.au
