Eight glacial cycles from an Antarctic ice core.
The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long--28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.
Augustin
Laurent
L
Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS, BP 96, 38402 St Martin d'Hères Cedex, France.
Barbante
Carlo
C
Barnes
Piers R F
PR
Barnola
Jean Marc
JM
Bigler
Matthias
M
Castellano
Emiliano
E
Cattani
Olivier
O
Chappellaz
Jerome
J
Dahl-Jensen
Dorthe
D
Delmonte
Barbara
B
Dreyfus
Gabrielle
G
Durand
Gael
G
Falourd
Sonia
S
Fischer
Hubertus
H
Flückiger
Jacqueline
J
Hansson
Margareta E
ME
Huybrechts
Philippe
P
Jugie
Gérard
G
Johnsen
Sigfus J
SJ
Jouzel
Jean
J
Kaufmann
Patrik
P
Kipfstuhl
Josef
J
Lambert
Fabrice
F
Lipenkov
Vladimir Y
VY
Littot
Geneviève C
GC
Longinelli
Antonio
A
Lorrain
Reginald
R
Maggi
Valter
V
Masson-Delmotte
Valerie
V
Miller
Heinz
H
Mulvaney
Robert
R
Oerlemans
Johannes
J
Oerter
Hans
H
Orombelli
Giuseppe
G
Parrenin
Frederic
F
Peel
David A
DA
Petit
Jean-Robert
JR
Raynaud
Dominique
D
Ritz
Catherine
C
Ruth
Urs
U
Schwander
Jakob
J
Siegenthaler
Urs
U
Souchez
Roland
R
Stauffer
Bernhard
B
Steffensen
Jorgen Peder
JP
Stenni
Barbara
B
Stocker
Thomas F
TF
Tabacco
Ignazio E
IE
Udisti
Roberto
R
Van De Wal
Roderik S W
RS
Van Den Broeke
Michiel
M
Weiss
Jerome
J
Wilhelms
Frank
F
Winther
Jan-Gunnar
JG
Wolff
Eric W
EW
Zucchelli
Mario
M