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Title
Climate and atmospheric history of the past 420,000 years from the Vostok ice core,
Antarctica
Permalink
https://escholarship.org/uc/item/7rx4413n
Journal
Nature, 399(6735)
ISSN
0028-0836
Authors
Petit, JR
Jouzel, J
Raynaud, D
et al.
Publication Date
1999-06-03
DOI
10.1038/20859
Supplemental Material
https://escholarship.org/uc/item/7rx4413n#supplemental
Copyright Information
This work is made available under the terms of a Creative Commons Attribution License,
availalbe at https://creativecommons.org/licenses/by/4.0/
Peer reviewed
eScholarship.org Powered by the California Digital Library
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© 1999 Macmillan Magazines Ltd
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articles
Climate and atmospheric history of
the past 420,000 years from the
Vostok ice core, Antarctica
J. R. Petit*, J. Jouzel
†
, D. Raynaud*, N. I. Barkov
‡
, J.-M. Barnola*, I. Basile*, M. Bender§, J. Chappellaz*, M. Davisk,
G. Delaygue
†
, M. Delmotte*, V. M. Kotlyakov¶, M. Legrand*, V. Y. Lipenkov
‡
, C. Lorius*,L.Pe
´
pin*, C. Ritz*,
E. Saltzmank & M. Stievenard
†
* Laboratoire de Glaciologie et Ge
´
ophysique de l’Environnement, CNRS, BP96, 38402, Saint Martin d’He
`
res Cedex, France
†
Laboratoire des Sciences du Climat et de l’Environnement (UMR CEA/CNRS 1572), L’Orme des Merisiers, Ba
ˆ
t. 709, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
‡
Arctic and Antarctic Research Institute, Beringa Street 38, 199397, St Petersburg, Russia
§ Department of Geosciences, Princeton University, Princeton, New Jersey 08544-1003, USA
k Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA
¶ Institute of Geography, Staromonetny, per 29, 109017, Moscow, Russia
........................................................................................................................................................................................................................................................
The recent completion of drilling at Vostok station in East Antarctica has allowed the extension of the ice record of
atmospheric composition and climate to the past four glacial–interglacial cycles. The succession of changes through
each climate cycle and termination was similar, and atmospheric and climate properties oscillated between stable
bounds. Interglacial periods differed in temporal evolution and duration. Atmospheric concentrations of carbon dioxide
and methane correlate well with Antarctic air-temperature throughout the record. Present-day atmospheric burdens of
these two important greenhouse gases seem to have been unprecedented during the past 420,000 years.
The late Quaternary period (the past one million years) is punc-
tuated by a series of large glacial–interglacial changes with cycles
that last about 100,000 years (ref. 1). Glacial–interglacial climate
changes are documented by complementary climate records
1,2
largely derived from deep sea sediments, continental deposits of
flora, fauna and loess, and ice cores. These studies have documented
the wide range of climate variability on Earth. They have shown that
much of the variability occurs with periodicities corresponding to
that of the precession, obliquity and eccentricity of the Earth’s
orbit
1,3
. But understanding how the climate system responds to this
initial orbital forcing is still an important issue in palaeoclimatol-
ogy, in particular for the generally strong ,100,000-year (100-kyr)
cycle.
Ice cores give access to palaeoclimate series that includes local
temperature and precipitation rate, moisture source conditions,
wind strength and aerosol fluxes of marine, volcanic, terrestrial,
cosmogenic and anthropogenic origin. They are also unique with
their entrapped air inclusions in providing direct records of past
changes in atmospheric trace-gas composition. The ice-drilling
project undertaken in the framework of a long-term collaboration
between Russia, the United States and France at the Russian Vostok
station in East Antarctica (788 S, 1068 E, elevation 3,488 m, mean
temperature −55 8C) has already provided a wealth of such infor-
mation for the past two glacial–interglacial cycles
4–13
. Glacial
periods in Antarctica are characterized by much colder temperatures,
reduced precipitation and more vigorous large-scale atmospheric
circulation. There is a close correlation between Antarctic tempera-
ture and atmospheric concentrations of CO
2
and CH
4
(refs 5, 9).
This discovery suggests that greenhouse gases are important as
amplifiers of the initial orbital forcing and may have significantly
contributed to the glacial–interglacial changes
14–16
. The Vostok ice
cores were also used to infer an empirical estimate of the sensitivity
of global climate to future anthropogenic increases of greenhouse-
gas concentrations
15
.
The recent completion of the ice-core drilling at Vostok allows us
to considerably extend the ice-core record of climate properties at
this site. In January 1998, the Vostok project yielded the deepest ice
core ever recovered, reaching a depth of 3,623 m (ref. 17). Drilling
then stopped ,120 m above the surface of the Vostok lake, a deep
subglacial lake which extends below the ice sheet over a large area
18
,
in order to avoid any risk that drilling fluid would contaminate the
lake water. Preliminary data
17
indicated that the Vostok ice-core
record extended through four climate cycles, with ice slightly older
than 400 kyr at a depth of 3,310 m, thus spanning a period
comparable to that covered by numerous oceanic
1
and continental
2
records.
Here we present a series of detailed Vostok records covering this
,400-kyr period. We show that the main features of the more recent
Vostok climate cycle resemble those observed in earlier cycles. In
particular, we confirm the strong correlation between atmospheric
greenhouse-gas concentrations and Antarctic temperature, as well
as the strong imprint of obliquity and precession in most of the
climate time series. Our records reveal both similarities and differ-
ences between the successive interglacial periods. They suggest the
lead of Antarctic air temperature, and of atmospheric greenhouse-
gas concentrations, with respect to global ice volume and Greenland
air-temperature changes during glacial terminations.
The ice record
The data are shown in Figs 1, 2 and 3 (see Supplementary Infor-
mation for the numerical data). They include the deuterium
content of the ice (dD
ice
, a proxy of local temperature change), the
dust content (desert aerosols), the concentration of sodium (marine
aerosol), and from the entrapped air the greenhouse gases CO
2
and
CH
4
, and the d
18
OofO
2
(hereafter d
18
O
atm
) which reflects changes
in global ice volume and in the hydrological cycle
19
.(dD and d
18
O
are defined in the legends to Figs 1 and 2, respectively.) All these
measurements have been performed using methods previously
described except for slight modifications (see figure legends).
The detailed record of dD
ice
(Fig. 1) confirms the main features of
the third and fourth climate cycles previously illustrated by the
coarse-resolution record
17
. However, a sudden decrease from inter-
glacial-like to glacial-like values, rapidly followed by an abrupt
return to interglacial-like values, occurs between 3,320 and 3,330 m.
© 1999 Macmillan Magazines Ltd
In addition, a transition from low to high CO
2
and CH
4
values (not
shown) occurs at exactly the same depth. In undisturbed ice, the
transition in atmospheric composition would be found a few metres
lower (due to the difference between the age of the ice and the age of
the gas
20
). Also, three volcanic ash layers, just a few centimetres apart
but inclined in opposite directions, have been observed—10 m
above this dD excursion (3,311 m). Similar inclined layers were
observed in the deepest part of the GRIP and GISP2 ice cores from
central Greenland, where they are believed to be associated with ice
flow disturbances. Vostok climate records are thus probably dis-
turbed below these ash layers, whereas none of the six records show
any indication of disturbances above this level. We therefore limit
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0 500 1,000 1,500 2,000 2,500 3,000 3,500
Depth (m)
–480
–460
–440
–420
–400
δD (‰)
3,250 3,300 3,350
–480
–460
–440
–420
Figure 1 The deuterium record. Deuterium content as a function of depth,
expressed as dD (in ‰ with respect to Standard Mean Ocean Water, SMOW). This
record combines data available down to 2,755 m (ref.13) and new measurements
performed on core 5G (continuous 1-m ice increments) from 2,755 m to 3,350 m.
Measurement accuracy (1j) is better than 1‰. Inset, the detailed deuterium
profile for the lowest part of the record showing a dD excursion between 3,320
and 3,330 m. dD
ice
ðin ‰Þ¼[ðD=HÞ
sample
=ðD=HÞ
SMOW
2 1] 3 1;000.
0 50,000 150,000 200,000 250,000 300,000 350,000 400,000
Age (yr
BP)
–480
–460
–440
–420
δD (‰)
0
50
100
Na (p.p.b.)
0.0
0.5
1.0
1.5
Dust (p.p.m.)
–0.5
0.0
0.5
1.0
0.0
0.5
1.0
Ice volume
390 kyr
110 kyr
5.1
5.3
5.4
5.5
7.1
7.3
7.5
8.5
9.1
9.3
11.1
11.24
11.3
a
b
c
d
e
Depth (m)
0 500 1,000 1,500 2,000 2,500 2,750 3,000 3,200 3,300
100,000
δ
18
O
atm
(‰)
Figure 2 Vostok time series and ice volume. Time series (GT4 timescale for ice
on the lower axis, with indication of corresponding depths on the top axis and
indication of the two fixed points at 110 and 390 kyr) of: a, deuterium profile (from
Fig. 1); b, d
18
O
atm
profile obtained combining published data
11,13,30
and 81 new
measurements performed below 2,760 m. The age of the gas is calculated as
described in ref. 20; c, seawater d
18
O (ice volume proxy) and marine isotope
stages adapted from Bassinot et al.
26
; d, sodium profile obtained by combination
of published and new measurements (performed both at LGGE and RSMAS) with
a mean sampling interval of 3–4 m (ng g
−1
or p.p.b); and e, dust profile (volume of
particles measured using a Coulter counter) combining published data
10,13
and
extended below 2,760 m, every 4 m on the average (concentrations are expressed
in mgg
−1
or p.p.m. assuming that Antarctic dust has a density of 2,500 kg m
−3
).
d
18
O
atm
ðin ‰Þ¼[ð
18
O=
16
OÞ
sample
=ð
18
O=
16
OÞ
standard
2 1] 3 1;000; standard is modern
air composition.
© 1999 Macmillan Magazines Ltd
the discussion of our new data sets to the upper 3,310 m of the
ice core, that is, down to the interglacial corresponding to marine
stage 11.3.
Lorius et al.
4
established a glaciological timescale for the first
climate cycle of Vostok by combining an ice-flow model and an ice-
accumulation model. This model was extended and modified in
several studies
12,13
. The glaciological timescale provides a chronol-
ogy based on physics, which makes no assumption about climate
forcings or climate correlation except for one or two adopted
control ages. Here, we further extend the Extended Glaciological
Timescale (EGT) of Jouzel et al.
12
to derive GT4, which we adopt as
our primary chronology (see Box 1). GT4 provides an age of 423 kyr
at a depth of 3,310 m.
Climate and atmospheric trends
Temperature. As a result of fractionation processes, the isotopic
content of snow in East Antarctica (dDord
18
O) is linearly related
to the temperature above the inversion level, T
I
, where precipitation
forms, and also to the surface temperature of the precipitation site,
T
S
(with DT
I
¼ 0:67DT
S
, see ref. 6). We calculate temperature
changes from the present temperature at the atmospheric level as
DT
I
¼ðDdD
ice
2 8Dd
18
O
sw
Þ=9, where Dd
18
O
sw
is the globally aver-
aged change from today’s value of seawater d
18
O, and 9‰ per 8Cis
the spatial isotope/temperature gradient derived from deuterium
data in this sector of East Antarctica
21
. We applied the above
relationship to calculate DT
S
. This approach underestimates DT
S
by a factor of ,2 in Greenland
22
and, possibly, by up to 50% in
Antarctica
23
. However, recent model results suggest that any under-
estimation of temperature changes from this equation is small for
Antarctica
24,25
.
To calculate DT
I
from dD, we need to adopt a curve for the change
in the isotopic composition of sea water versus time and correlate it
with Vostok. We use the stacked d
18
O
sw
record of Bassinot et al.
26
,
scaled with respect to the V19-30 marine sediment record over their
common part that covers the past 340 kyr (ref. 27) (Fig. 2). To avoid
distortions in the calculation of DT
I
linked with dating uncertain-
ties, we correlate the records by performing a peak to peak adjust-
ment between the ice and ocean isotopic records. The d
18
O
sw
correction corresponds to a maximum DT
I
correction of ,1 8C
and associated uncertainties are therefore small. We do not attempt
to correct DT
I
either for the change of the altitude of the ice sheet or
for the origin of the ice upstream of Vostok
13
; these terms are very
poorly known and, in any case, are also small (,1 8C).
The overall amplitude of the glacial–interglacial temperature
change is ,8 8C for DT
I
(inversion level) and ,12 8C for DT
S
, the
temperature at the surface (Fig. 3). Broad features of this record are
thought to be of large geographical significance (Antarctica and part
of the Southern Hemisphere), at least qualitatively. When examined
in detail, however, the Vostok record may differ from coastal
28
sites
in East Antarctica and perhaps from West Antarctica as well.
Jouzel et al.
13
noted that temperature variations estimated from
deuterium were similar for the last two glacial periods. The third
and fourth climate cycles are of shorter duration than the first two
cycles in the Vostok record. The same is true in the deep-sea record,
where the third and fourth cycles span four precessional cycles
rather than five as for the last two cycles (Fig. 3). Despite this
difference, one observes, for all four climate cycles, the same
‘sawtooth’ sequence of a warm interglacial (stages 11.3, 9.3, 7.5
and 5.5), followed by increasingly colder interstadial events, and
ending with a rapid return towards the following interglacial. The
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0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000
Age (yr
BP)
–0.5
0.0
0.5
1.0
δ
18
O
atm
(‰)
–8
–6
–4
–2
0
2
Temperature (°C)
200
220
240
260
280
CO
2
(p.p.m.v.)
400
500
600
700
CH
4
(p.p.b.v.)
–50
0
50
100
Insolation J 65°N
a
b
c
d
e
Depth (m)
0 500 1,000 1,500 2,000 2,500 2,750 3,000 3,200 3,300
Figure 3 Vostok time series and insolation. Series with respect to time (GT4
timescale for ice on the lower axis, with indication of corresponding depths on the
top axis) of: a,CO
2
; b, isotopic temperature of the atmosphere (see text); c,CH
4
;
d, d
18
O
atm
; and e, mid-June insolation at 658 N (in W m
−2
) (ref. 3). CO
2
and CH
4
measurements have been performed using the methods and analytical pro-
cedures previously described
5,9
. However, the CO
2
measuring system has been
slightly modified in order to increase the sensitivity of the CO
2
detection. The
thermal conductivity chromatographic detector has been replaced by a flame
ionization detector which measures CO
2
after its transformation into CH
4
. The
mean resolution of the CO
2
(CH
4
) profile is about 1,500 (950) years. It goes up to
about 6,000 years for CO
2
in the fractured zones and in the bottom part of the
record, whereas the CH
4
time resolution ranges between a few tens of years to
4,500 years. The overall accuracy for CH
4
and CO
2
measurements are 620 p.p.b.v.
and 2–3 p.p.m.v., respectively. No gravitational correction has been applied.
© 1999 Macmillan Magazines Ltd
coolest part of each glacial period occurs just before the glacial
termination, except for the third cycle. This may reflect the fact that
the June 658 N insolation minimum preceding this transition
(255 kyr ago) has higher insolation than the previous one (280 kyr
ago), unlike the three other glacial periods. Nonetheless, minimum
temperatures are remarkably similar, within 1 8C, for the four
climate cycles. The new data confirm that the warmest temperature
at stage 7.5 was slightly warmer than the Holocene
13
, and show that
stage 9.3 (where the highest deuterium value, −414.8‰, is found)
was at least as warm as stage 5.5. That part of stage 11.3, which is
present in Vostok, does not correspond to a particularly warm
climate as suggested for this period by deep-sea sediment records
29
.
As noted above, however, the Vostok records are probably disturbed
below 3,310 m, and we may not have sampled the warmest ice of this
interglacial. In general, climate cycles are more uniform at Vostok
than in deep-sea core records
1
. The climate record makes it unlikely
that the West Antarctic ice sheet collapsed during the past 420 kyr
(or at least shows a marked insensitivity of the central part of East
Antarctica and its climate to such a disintegration).
The power spectrum of DT
I
(Fig. 4) shows a large concentration
of variance (37%) in the 100-kyr band along with a significant
concentration (23%) in the obliquity band (peak at 41 kyr). This
strong obliquity component is roughly in phase with the annual
insolation at the Vostok site
4,6,15
. The variability of annual insolation
at 788 S is relatively large, 7% (ref. 3). This supports the notion that
annual insolation changes in high southern latitudes influence
Vostok temperature
15
. These changes may, in particular, contribute
to the initiation of Antarctic warming during major terminations,
which (as we show below) herald the start of deglaciation.
There is little variance (11%) in DT
I
around precessional periodi-
cities (23 and 19 kyr). In this band, the position of the spectral peaks
is affected by uncertainties in the timescale. To illustrate this point,
we carried out, as a sensitivity test, a spectral analysis using the
control points provided by the d
18
O
atm
record (see Table 1). The
position and strength of the 100- and 40-kyr-spectral peaks are
unaffected, whereas the power spectrum is significantly modified
for periodicities lower than 30 kyr.
Insolation. d
18
O
atm
strongly depends on climate and related proper-
ties, which reflect the direct or indirect influence of insolation
19
.Asa
result, there is a striking resemblance between d
18
O
atm
and mid-June
insolation at 658 N for the entire Vostok record (Fig. 3). This
provides information on the validity of our glaciological timescale
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0
25
50
75
100
Power (×10
3
)
∆T
a
Dust
Na
0246
0
25
50
75
100
Power (×10
3
)
0246
Frequency (×10
–5
)
δ
18
O
atm
CO
2
0246
CH
4
100 kyr
41 kyr
23 kyr
19 kyr
100 kyr
41 kyr
23 kyr
19 kyr
100 kyr
41 kyr
23 kyr
19 kyr
a
bc
d
e
f
Figure 4 Spectral properties of the Vostok time series. Frequency distribution (in
cycles yr
−1
) of the normalized variance power spectrum (arbitrary units). Spectral
analysis was done using the Blackman-Tukey method (calculations were
performed with the Analyseries software
47
): a, isotopic temperature; b, dust; c,
sodium; d, d
18
O
atm
; e,CO
2
; and f,CH
4
. Vertical lines correspond to periodicities of
100, 41, 23 and 19 kyr.
Box 1 The Vostok glaciological timescale
We use three basic assumptions
12
to derive our glaciological timescale
(GT4); (1) the accumulation rate has in the past varied in proportion to the
derivative of the water vapour saturation pressure with respect to tem-
perature at the level where precipitation forms (see section on the isotope
temperature record), (2) at any given time the accumulation between
Vostok and Dome B (upstream of Vostok) varies linearly with distance
along the line connecting those two sites, and (3) the Vostok ice at 1,534 m
corresponds to marine stage 5.4 (110 kyr) and ice at 3,254 m corresponds
to stage 11.2.4 (390 kyr).
Calculation of the strain-induced thinning of annual layers is now
performed accounting for the existence of the subglacial Vostok lake.
Indeed, running the ice-flow model
48
with no melting and no basal sliding
as done for EGT
12
leads to an age .1,000 kyr for the deepest level we
consider here (3,310 m), which is much too old. Instead, we now allow for
moderate melting and sliding. These processes diminish thinning for the
lower part of the core and provide younger chronologies. We ran this age
model
48
over a large range of values of the model parameters (present-
day accumulation at Vostok, A, melting rate, M, and fraction of horizontal
velocity due to base sliding, S) with this aim of matching the assumed
ages at 1,534 and 3,254 m. This goal was first achieved (ages of 110 and
392 kyr) with A ¼ 1:96 g cm
2 2
yr
2 1
, and M and S equal respectively to
0.4 mm yr
−1
and 0.7 for the region 60 km around Vostok where the base
is supposed to reach the melting point (we set M ¼ 0 and S ¼ 0 else-
where). These values are in good agreement with observations for A
(2:00 6 0:04 g cm
2 2
yr
2 1
over the past 200 yr) and correspond to a reason-
able set of parameters for M and S. We adopt this glaciological timescale
(GT4), which gives an age of 423 kyr at 3,310 m, without further tuning
(Fig. 2). GT4 never differs by more than 2 kyr from EGTover the last climate
cycle and, in qualitative agreement with recent results
49
, makes termina-
tion I slightly older (by ,700 yr). We note that it provides a reasonable age
for stage 7.5 (238 kyr) whereas Jouzel et al.
13
had to modify EGT for the
second climate cycle by increasing the accumulation by 12% for ages
older than 110 kyr. GT4 never differs by more than 4 kyr from the orbitally
tuned timescale of Waelbroeck et al.
50
(defined back to 225 kyr), which is
within the estimated uncertainty of this latter timescale. Overall, we have
good arguments
11,50–52
to claim that the accuracy of GT4 should be better
than 65 kyr for the past 110 kyr.
The strong relationship between d
18
O
atm
and mid-June 658 N insolation
changes (see text and Fig. 3) enables us to further evaluate the overall
quality of GT4. We can use each well-marked transition from high to low
d
18
O
atm
to define a ‘control point’ giving an orbitally tuned age. The mid-
point of the last d
18
O
atm
transition (,10 kyr ago) has nearly the same age as
the insolation maximum (11 kyr). We assume that this correspondence
also holds for earlier insolation maxima. The resulting control points (Fig. 3
and Table 1) are easy to define for the period over which the precessional
cycle is well imprinted in 658 N insolation (approximately between 60 and
340 kyr) but not during stages 2 and 10 where insolation changes are
small. The agreement between the d
18
O
atm
control points and GT4 is
remarkably good given the simple assumptions of both approaches. This
conclusion stands despite the fact that we do not understand controls on
d
18
O
atm
sufficiently well enough to know about the stability of its phase
with respect to insolation. We assume that the change in phase does not
exceed 66 kyr (1/4 of a precessional period).
We conclude that accuracy of GT4 is always better than 615 kyr, better
than 610 kyr for most of the record, and better than 65 kyr for the last
110 kyr. This timescale is quite adequate for the discussions here which
focus on the climatic information contained in the Vostok records
themselves.
![Figure 1 The deuterium record. Deuterium content as a function of depth, expressedas dD (in ‰ with respect to StandardMean Ocean Water, SMOW). This record combines data available down to 2,755m (ref.13) and new measurements performed on core 5G (continuous 1-m ice increments) from 2,755m to 3,350m. Measurement accuracy (1j) is better than 1‰. Inset, the detailed deuterium profile for the lowest part of the record showing a dD excursion between 3,320 and 3,330m. dDiceðin ‰Þ ¼ [ðD=HÞsample=ðD=HÞSMOW 2 1] 3 1;000.](/figures/figure-1-the-deuterium-record-deuterium-content-as-a-1m9usu0e.webp)
