High-resolution record of Northern Hemisphere climate extending into the last interglacial period 

Nature, Vol. 431, p. 147-151, 2004 

North Greenland Ice Core Project members:
K.K. Andersen, H.B. Clausen, D. Dahl-Jensen, N.S. Gundestrup (deceased), C.S. Hvidberg, S.J. Johnsen, S.O. Rasmussen, M.-L. Siggaard-Andersen, J.P. Steffensen and A. Svensson
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
N. Azuma and M. Takata
Nagaoka University of Technology, 1603-1 Kamitomioka-machi, Nagaoka 940-2188, Japan
J.-M. Barnola, J. Chappellaz and D. Raynaud
Laboratoire de Glaciologie et Géophysique de l'Environnement (CNRS), BP 96, 38402 St Martin d'Héres Cedex, France
M. Bigler, J. Flückiger, C. Huber, M. Leuenberger, R. Röthlisberger, J. Schwander and T. Stocker
Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012, Switzerland
P. Biscaye
Lamont-Doherty Earth Observatory of Columbia University, Rte 9W - PO Box 1000, Palisades, New York 10964-8000, USA
N. Caillon, J. Jouzel, A. Landais and V. Masson-Delmotte
Institute Pierre Simon Laplace/Laboratoire des Sciences du Climat et de l'Environnement, UMR CEA-CNRS, CE Saclay, Omme des Merisiers, 91191 Gir-Sur-Yvette, France
H. Fischer, D. Fritzsche, S. Kipfstuhl, H. Miller, U. Ruth and F. Wilhelms
Alfred-Wegener-Institute for Polar and Marine Research (AWI), Postfach 120161, D-27515 Bremerhaven, Germany
Y. Fujii, K. Goto-Azuma, H. Motoyama and O. Watanabe
National Institute of Polar Research, Kaga 1-9-10, Itabashi-ku, Tokyo 173-8515 Japan
K. Grønvold
Nordic Volcanological Institute, Grensásvegur 50, 108 Reykjavik, Iceland
M. Hansson and U. Jonsell
Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91, Stockholm, Sweden
R. Lorrain, D. Samyn and J.-L. Tison
Département des Sciences de la terre et de l'Environnement, Faculté des Sciences, CP 160/03, Université Libre de Bruxelles, 50 avenue FD Roosevelt, B1050 Brussels, Belgium
H. Narita
Research Institute for Humanity and Nature, 335 Takashima-cho, Marutamachi-dori Kawaramachi nishi-iru, Kamigyo-ku, Kyoto 602-0878, Japan
T. Popp and J.W.C. White
INSTAAR, Campus Box 450, University of Colorado, Boulder, Colorado 80309-0450, USA
H. Shoji
Kitami Institute of Technology, Koencho 165, Kitami, Hokkaido 090-8507 Japan
A.E. Sveinbjörnsdottir
Raunvísindastofnun Háskólans, Dunhagi 3, Iceland
Th. Thorsteinsson
National Energy Authority, Grensásvegur 9, IS-108 Reykjavík, Iceland

Two deep ice cores from central Greenland, drilled in the 1990s, have played a key role in climate reconstructions of the Northern Hemisphere, but the oldest sections of the cores were disturbed in chronology owing to ice folding near the bedrock. Here we present an undisturbed climate record from a North Greenland ice core, which extends back to 123,000 years before the present, within the last interglacial period. The oxygen isotopes in the ice imply that climate was stable during the last interglacial period, with temperatures 5 oC warmer than today. We find unexpectedly large temperature differences between our new record from northern Greenland and the undisturbed sections of the cores from central Greenland, suggesting that the extent of ice in the Northern Hemisphere modulated the latitudinal temperature gradients in Greenland. This record shows a slow decline in temperatures that marked the initiation of the last glacial period. Our record reveals a hitherto unrecognized warm period initiated by an abrupt climate warming about 115,000 years ago, before glacial conditions were fully developed. This event does not appear to have an immediate Antarctic counterpart, suggesting that the climate see-saw between the hemispheres (which dominated the last glacial period) was not operating at this time.