EPI2004a

EPI2004a
articles
Eight glacial cycles from an Antarctic
ice core
EPICA community members*
*A full list of authors appears at the end of the paper
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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.
The climate of the last 500,000 years (500 kyr) was characterized by
extremely strong 100-kyr cyclicity, as seen particularly in ice-core1
and marine-sediment2,3 records. During the earlier part of the
Quaternary (before 1 million years ago; 1 Myr BP ), cycles of 41 kyr
dominated. The period in between shows intermediate behaviour,
with marine records showing both frequencies and a lower amplitude of the climate signal2,3. The observed frequencies arise from
parameters of the Earth’s orbit that control the amount, and the
seasonal and latitudinal distribution, of solar radiation4. However,
the reasons for the dominance of the 100-kyr (eccentricity) over the
41-kyr (obliquity) band in the later part of the record, and the
amplifiers that allow small changes in radiation to cause large
changes in global climate, are not well understood. New records
of the earlier periods, looking at parameters unavailable in marine
records, are needed.
Ice cores provide the most direct and highly resolved records of
(especially) atmospheric parameters over these timescales. They
record climate signals, as well as forcing factors of global significance
such as greenhouse gases and of more regional significance such as
atmospheric aerosol content. Until now, ice-core data have been
available only for the past 420 kyr, with the longest record coming
from Vostok in East Antarctica1, supported by the 340-kyr record
from Dome Fuji5. These data indicated the similarities of the last
four glacial terminations. They showed that glacials and interglacials had similar bounds in the measured properties over the
last four cycles. Most tellingly, they showed the very close association between greenhouse gases1,6 (CO2, CH4) and climate (as
recorded using the Antarctic temperature proxy, the deuterium/
hydrogen ratio in ice, represented as dD) over this period. The
Vostok record has become a compelling target against which other
records and modelling efforts are tested.
The European Project for Ice Coring in Antarctica (EPICA) is a
consortium of laboratories and Antarctic logistics operators from
ten nations, with the goal of obtaining two deep ice cores in East
Antarctica. The study of one core, from Kohnen Station in the
Dronning Maud Land sector of Antarctica (see Supplementary
Fig. 1) is aimed at producing a high-resolution record of at least
one glacial–interglacial cycle in the sector of Antarctica facing the
Atlantic Ocean, for comparison with Greenland records7. The
second core (named EDC) from Dome C (758 06 0 S, 1238 21 0 E,
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altitude 3,233 m above sea level), discussed here, is aimed at
producing a record of the longest time period possible. The site8
has an ice thickness of 3,309 ^ 22 m; the current drilling depth is
3,190 m, of which 3,139 m has been analysed for a wide range of
constituents. The current mean annual surface temperature is
254.5 8C, and the snow accumulation rate is 25 kg m22 yr21
(2.5 cm water equivalent per year). The drill site is 56 km from
the site of a previous Dome C core9 that provided records extending
into the last glacial period, and 560 km from the site of the Vostok
cores1. The completion of the Dome C core was delayed when the
first drilling became stuck at 788 m in 1999, and this shorter EDC96
core has already yielded many important results from the last 45 kyr
(see, for example, refs 10–14).
Here we present the EDC records of dD and other parameters,
analysed at low resolution, for the available core. We show that the
core represents 740 kyr, including all of marine isotope stage (MIS)
11, which was not completed in the Vostok record, and running
through a further three complete 100-kyr cycles, to MIS 18.4. We
compare the amplitude and frequency structure of the period before
MIS 11 with that of the more recent period. We focus in more detail,
with new greenhouse-gas and ice-chemical data, on Termination V,
from MIS 12 to MIS 11, discussing first the integrity of the record.
The different parameters measured on this termination are then
discussed in terms of similarities to and differences from younger
terminations.
Stratigraphy of the EDC core
The ice-core data (see Methods) are reported in Fig. 1 as a function
of depth. In this section, conductivity, grain size, dust and dD data,
taken together, allow us to define a reliable stratigraphy of the core
in terms of terminations and of broad correspondence with the
deep-sea record. In the following section, we derive a timescale—
which should be considered preliminary—and develop arguments
supporting our claim that the core stratigraphy is undisturbed at the
current depth (3,139 m) despite the relative proximity of the bedrock (less than 200 m).
Under the conditions at Dome C, both measurements (see
Methods) of electrical conductivity15 are dominated by variations
in the acidity of the ice16. This property does not vary in a simple
way with climate, increasing in both very cold and very warm stages,
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with the lowest values in intermediate climates. Cold periods in
Antarctica are characterized by much greater dust fallout than is
found during interglacials (for example, the Last Glacial Maximum
(LGM)/Holocene ratio of 26 for dust flux13), related to a combination of increased aridity and wind strength. Large numbers of
dust particles within the ice lead to a decrease in the ice-grain
growth rate17. Consequently, each significant decrease of the average
grain radius (Fig. 1) also marks an interglacial to glacial transition.
The isotopic composition of the ice, dD (used here) and d18O, is
classically used as an indicator of temperature change. Isotopic
models predict that d values should vary linearly with temperature
in mid- and high latitudes. There is now a series of arguments
supporting the use of this present-day temperature/isotope spatial
slope to interpret isotopic records from Antarctica18,19, at least for
deep ice cores from the East Antarctic plateau.
Electrical, dust and dD (Fig. 2) data can easily be matched
between the EDC and Vostok cores into stage 11. We deduce that
ice from 3,310 m at Vostok and from ,2,770 m at EDC corresponds
to the same time period (423 kyr BP in the GT4 Vostok chronology).
Transition V is then very clearly marked both in the dust, grain size
and dD records with the coldest part of MIS 12 at around ,2,790 m
(Fig. 1), and with Termination V (that is, the MIS 12 to MIS 11
transition) roughly corresponding to the depth interval between
2,790 and 2,760 m.
Below the dielectric-profiling peak corresponding to MIS 11
there is a large depth interval with low dielectric-profiling values.
There is, however, a clear dust peak, as well as a large decrease in the
average grain size, at a depth of 2,910 m, which should correspond
to the cold MIS 14, thus implying that there is no dielectric-profiling
peak within MIS 13. The dD record confirms that the interglacial
MIS 13 peaks at a depth of 2,842 m, but is considerably colder
than subsequent interglacials. This intermediate climate is insufficient to give a dielectric-profiling peak, probably because of reduced
preservation of volatile acids20.
From the dD record, we first note a clear change in the amplitude
of glacial–interglacial changes before and after MIS 12, with the
older period being characterized by just one minimum as deep as
those observed during the last 400 kyr, and by consistently lower
maxima (by about 20‰). As discussed below, this change of
amplitude corresponds to the mid-Brunhes climate shift (and
does not result from some smoothing process in the ice). There is
an excellent correspondence between the dD and the dust record
and based on these we can assign the base of the transition at
,3,042 m to the next cold stage, MIS 16.2. In the deep-sea core
record, stage 16.2 corresponds to particularly low sea level and was
probably very cold. This is exactly what is seen in the dD where,
before MIS 12, only stage 16 reached dD levels as low as those of the
LGM. The next dD peaks (low dust) can then be attributed to full
interglacial 17 and interstadial 18.3 with the bottom of the record
corresponding to MIS 18.4.
Timescale and integrity of the deep ice
The timescale (called EDC2; see Methods) developed for the Dome
C deep ice core is based on an inverse dating method21, constrained
by a small number of control age windows, which are mainly set to
glacial terminations by comparison to the marine records. The fact
that a simple one-dimensional model with only four free parameters can be matched (to 3,139 m depth) so well, in both timing
and shape, with the orbitally tuned marine records (Fig. 2c) is
evidence for the integrity of the stratigraphy of the Dome C record.
The good match extends through the period from 338 to 626 kyr, in
which there are no imposed control windows. The difference
between the ages of gas bubbles and the surrounding ice was
computed with a firn model22.
The first section of EDC ice that is novel, that is, older than was
5.5
EDC
Vostok
Figure 1 Measured parameters from the EPICA Dome C ice core, on an ice depth scale.
a, dD, averaged over 3.85-m sections. b, Grain radius, measured approximately every
10 m. c, Dust concentration—below 787 m, there is one sample every 5.5 m; above that,
one sample every 1.5 m. d, Electrical data (as discussed in the Methods), in 1-m
averages. Termination V is marked by an arrow in a.
624
Figure 2 Comparison of EPICA Dome C data with other palaeoclimatic records.
a, Insolation records4. Upper blue curve (left axis), mid-July insolation at 658 N; lower
black curve (right axis), annual mean insolation at 758S, the latitude of Dome C. b, dD from
EPICA Dome C (3,000-yr averages). Vostok dD (red) is shown for comparison1 and some
MIS stage numbers are indicated; the locations of the control windows (below 800-m
depth) used to make the timescale are shown as diamonds on the x axis. c, Marine oxygen
isotope record. The solid blue line is the tuned low-latitude stack of site MD900963 and
ODP6773; to indicate the uncertainties in the marine records we also show (dashed red
line) another record, which is a stack of seven sites for the last 400 kyr but consisting
only of ODP site 677 for the earlier period2. Both records have been normalized to their
long-term average. d, Dust from EPICA Dome C.
©2004 Nature Publishing Group
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articles
obtained at Vostok, is that of Termination V. The integrity of this
section can be tested using the depth difference expected between
contemporaneous events recorded in the gas and the solid phase.
We measured CO2 and CH4 mixing ratios in the air enclosed in the
ice at ,1-m resolution between 2,760 and 2,800 m (Fig. 3). From
the Vostok findings over the last four terminations23, we expect the
following pairs of events to be roughly synchronous: (1) the CO2
peak/dD peak, (2) the start of CO2 increase/start of dD increase.
The depth offset (Ddepth) values for these two pairs of 5 to 7 m are
in reasonable agreement with Ddepth values calculated with the firn
densification model, taking into account the thinning function
obtained with the ice-flow model (Fig. 3). These observations
support the conclusion that this part of the Dome C record is
undisturbed, that is, that there is no folding of the ice.
Although visible ash layers tilted by a few degrees from the
horizontal have been observed in the deeper ice, so far we have
observed none of the highly inclined layers and overturned folds
that were associated with stratigraphic disturbance in the lowest
10% of the deep Greenland (Summit) ice cores. The electrical
records to 3,190 m also show no unexpectedly rapid changes, of
the kind that might be diagnostic of folding. In conclusion, all the
evidence supports the integrity of the ice-core stratigraphy to
3139 m.
Antarctic climate beyond MIS 11
One of the paradoxes of Quaternary climate is the dominance of
100-kyr periodicity in the past few climatic cycles, even though the
amplitude of insolation changes at this period is rather small. This
Figure 3 Termination V in the EPICA Dome C ice core on an ice depth scale. The top panel
shows the ice-core parameters: circles, CO2; diamonds, CH4; line with no symbols, dD;
crosses, dust. The lower panel shows the modelled difference in depth between ice and
air of the same age (line) along with estimates of the actual difference (error bars are
based on uncertainty in aligning common events) for events considered roughly
contemporaneous on the basis of their behaviour in later terminations at Vostok. Event 1,
CO2 peak/dD peak; event 2, CO2 early increase/dD early increase.
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can be addressed by examining changes in the amplitude and
frequency of climate through the Quaternary period. On the basis
mainly of ice-volume records, two major transitions have been
identified. The mid-Pleistocene revolution (MPR) is characterized
by an increase in mean global ice volume, and a change in the
dominant period from 41 to 100 kyr (ref. 2). Its timing is often
considered to be at about 900 kyr BP (that is, before the scope of this
paper). A second distinct climate change, the mid-Brunhes event
(MBE, for example24), roughly corresponds to the transition
between stage 12 and stage 11 (Termination V) about 430 kyr ago.
The MBE is characterized by a further increase of ice-volume
variations with, from then to the present day, four large-amplitude
100-kyr-dominated glacial–interglacial cycles. The intermediate
period between the MPR and the MBE is characterized by a lessclear pattern. This schematic description of Quaternary climate,
largely based on deep-sea isotopic records of ice-volume changes,
also holds for at least some sea surface temperature records. For
example, a composite South Atlantic 1,830-kyr record25 shows cold
and relatively stable summer temperatures before the MPR followed
by higher-amplitude fluctuations between the MPR and the MBE
and much stronger variations thereafter. Now we have the opportunity to examine the pre-MBE signal in Antarctic temperature and
dust.
In the EDC dD record (Fig. 2), as in the marine-isotope records,
the most striking feature is the greater amplitude of glacial–interglacial change in the period after Termination V (with 430 kyr as the
boundary), compared to the earlier period. The standard deviation
of the signals increases by 45% for EDC and 12% for the d18O record
of ref. 3; other planktonic series show a similar feature24. The Devil’s
Hole calcite isotopic record26, which, however, extends only back to
565 kyr BP, also shows less variability before than after the MBE and
indeed resembles the EDC record over the part common to both
records. In detail, the period before Termination V in EDC is
characterized by somewhat less cold glacial maxima (with the
exception of stage 16.2), but by very significantly less warm interglacials (Fig. 4). Less extreme (weaker amplitude) interglacials
occupied a larger proportion of each glacial/interglacial cycle,
with the result that the mean dD value before and after 430 kyr is
quite similar. The new ice-core data strongly emphasize the contrast
in climate before and after the MBE.
The driving mechanisms for neither the MPR nor the MBE are as
yet well understood. Some properties of the insolation curves have
Figure 4 Histogram of dD values before and after 430 kyr. The bars show the occurrence
of values within 5‰ windows for each of the periods, indicating that for the earlier
period, there are no very warm values, but the time spent in warm and cold periods is
more even than in the later period.
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Figure 5 Comparison of Termination V plus MIS 11 with Termination I plus Holocene. dD
data for MIS 11 (1-kyr averages) are shown as a solid blue line using the lower x axis; data
for the Holocene are shown as a dashed red line using the upper x axis. Various
alignments could be made, but we have adjusted the x axes so that the start of each
termination is aligned. A horizontal line is drawn at 2403‰.
changed progressively over the last 800 kyr, with an increased
amplitude of obliquity changes, for example, and therefore an
increased variability of annual local insolation (Fig. 2a) in the
later part of the record. However, none of the simple conceptual
models developed to simulate the timing of the Pleistocene glaciations has been able to suggest an explanation of the MBE. The
climate became more orderly and predictable after the MBE,
perhaps as a result of the emergence of new feedback mechanisms
linked with changes in boundary conditions, such as the strength of
ocean circulation, albedo, carbon dioxide or isostasy24. At this stage,
we have no additional clues allowing us to favour any one of these
feedbacks, or to formulate other possibilities, but to obtain a
detailed carbon dioxide record over 800,000 yr should certainly be
helpful.
A final issue concerning the complete record is the stability in the
size of the Antarctic ice sheet. Preliminary measurements of air
content made between 2762.1 and 2783.0 m depth (MIS 11),
between 3054.7 and 3059.1 m (MIS 16.3) and between 3099.8 and
3100.9 m (MIS 17.3) show the same mean value as that of EDC ice
dating from the last 40 kyr (0.089 cm3 g21). This suggests27 that over
the last 700 kyr, the surface elevation in this central part of East
Antarctica has been as stable as during the last 40 kyr. This sets
constraints, probably of the order of 5 m (ref. 28), on the possible
contribution of this part of East Antarctica to changes in sea level29.
Termination V
MIS 11 emerges as a key interglacial, both as viewed from the
atmosphere in the EDC record and from the ocean in the d18O
marine records. It delimits the frontier between two different
patterns of climate, and has been identified as a unique and
exceptionally long interglacial30. Some authors suggest that, because
the orbital parameters (low eccentricity and consequently weak
precessional forcing) are similar to those of the present and the next
tens of thousands of years, MIS 11 may be the best analogue for
present and future climate without human intervention31. In this
context, we note (Fig. 5) that, on the EDC2 timescale, dD (our
temperature proxy) remains above 2403‰ (the minimum 300-yr
average value observed during the full Holocene epoch) for 28 kyr in
MIS 11 (apart from a brief reversal near the start); in the Holocene,
dD has so far been above 2403‰ for 12 kyr. The rate of change in
dD is very similar in Terminations Vand I. Both terminations show a
clear temperature reversal, but the one in the earlier period occurs
after interglacial warmth has already been achieved. Thus the
reversal at about 420 kyr might be seen as analogous to the Antarctic
cold reversal (ACR) that occurred during Termination I at around
13 kyr, or it might be seen as similar to the dip (at about 8 kyr) that
occurred after the early Holocene warm period.
Our low-resoluion data for CO2, CH4 (Fig. 3) and other parameters already provide information on how Termination V mimics or
differs from younger terminations in terms of coupling between
climate and greenhouse gases. With a minimum at 200 p.p.m.v. and
380 p.p.b.v. at the end of MIS 12 and a maximum at 275 p.p.m.v. and
680 p.p.b.v. at the start of MIS 11, CO2 and CH4 mixing ratios lie
within the range observed during younger glacials and interglacials1,
the MIS 12 values being slightly at the higher end of the glacial
range. These observations and the incomplete MIS 11 CO2 record
measured along the Vostok ice core28 rule out unusual greenhouse
conditions during MIS 1132 or a link between coral-reef growth and
the intense carbonate dissolution of MIS 11 through unusual CO2
mixing ratios30. Other parameters measured on the core (Table 1),
representing conditions and transport in different compartments of
the environment, have very similar (glacial) values at equivalent
points just before Terminations I and V and very similar (interglacial) values just after the two transitions. This confirms that, in all
the proxies we are able to examine, there is no significant long-term
trend in the period since the MBE.
The general shape of the greenhouse gas increases resembles
younger terminations, that is, a regular trend for CO2 and a twostep transition for CH4 (slow increase followed by a rapid jump
towards interglacial values); however, no Younger-Dryas-like event
is observed in our CH4 profile.
The most striking feature concerns the relative timing of the CO2
and CH4 increases compared with younger terminations: whereas
CH4 started to increase concomitantly with CO2 (and Antarctic
temperature) during the last four terminations, at Termination V it
leaves its glacial background 4 to 5 kyr later than CO2, by which time
the latter had already increased by about 50 p.p.m.v. Similarly, the
rapid jump of CH4 punctuating the second part of its transition
takes place when CO2 approaches its maximum. Note that this is
also the time when Antarctic temperature starts a slow decrease, that
is, a typical expression of a bipolar see-saw as observed during stage
3 (ref. 33) and possibly Termination I12. Following its rapid jump at
Table 1 Concentrations of major analytes measured along the EDC ice core
Analytes
6–8 kyr BP
(after Termination I)
20–22 kyr BP
(before Termination I)
416–418 kyr BP
(after Termination V)
430–432 kyr BP
(before Termination V)
...................................................................................................................................................................................................................................................................................................................................................................
dD (‰)
CO2 (p.p.m.v.)
CH4 (p.p.b.v.)
Dust (mg kg21)
Na (mg kg21)
21
SO22
)
4 (mg kg
2399
260
600
14
20
92
2442
185
360
680
101
201
2395
270
670
24
23
98
2442
200
390
630
99
216
...................................................................................................................................................................................................................................................................................................................................................................
Gas values are for Dome C. No corrections for interhemispheric differences or global averages have been applied. Data is shown for approximately equivalent periods before and after Terminations I and V.
626
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the end of the termination, CH 4 continues to increase by
,100 p.p.b.v. for 2 to 3 kyr, another unusual feature when compared to the CH4 trends during the early part of MIS 1, 5, 7 and 9
(ref. 1).
A thorough discussion of the causes of these greenhouse-gas
peculiarities during Termination V is beyond the scope of this paper.
But evidently the similarities and differences observed with younger
terminations will stimulate the debate on how greenhouse gas and
climate are coupled on Quaternary timescales.
Prospects from the rest of the core
In this paper, we have shown the extended climate record back to
740 kyr, and that the pattern of climate before MIS 11 was different
to that which has followed for the past four glacial cycles. Although
the results from MIS 11 indicate that without human intervention a
climate similar to the present one would extend well into the future,
the predicted increases in greenhouse-gas concentrations make this
unlikely34.
According to our preliminary timescale, extending the record to
3,190 m (ice already drilled but not analysed) will take the record
back to 807 ^ 10 kyr (MIS 20.2). The electrical records already
obtained on this ice (Fig. 1), although difficult to interpret simply in
terms of climate, certainly suggest that another glacial cycle will be
found in this ice. This ice should include the Brunhes–Matuyama
magnetic reversal, generally dated to about 780 kyr, and therefore
give us the first indication of how a reversal is recorded in
cosmogenic isotopes such as 10Be.
There remains up to 120 m of ice still to drill. This will be difficult
to obtain because the ice is near to the melting temperature. The
timescale EDC2 extended to the base gives an age of 960 ^ 20 kyr.
Therefore, when the record is complete, we could expect to reach
MIS 26 (just beyond the MPR), assuming that the integrity of the
stratigraphy and all the approximations of the dating method are
still reasonable down to the base. It will be of particular interest to
see how the tight coupling between greenhouse gases and Antarctic
temperature (dD) seen in the last 420 kyr evolves through the earlier
parts of the record.
A
Methods
Analysis
The electrical conductivity measurement determines the d.c. conductance between
electrodes on a fresh ice surface. Dielectric profiling determines the conductivity of the ice
at higher frequencies. Both were measured in the field at a temperature of 220 ^ 2 8C,
corrected15,16 to 215 8C. Data were collected at high resolution and averaged to 1 m.
Vertical thin sections were prepared in the field at a periodicity of 10 m, then digitized and
analysed using an image analysis procedure35 to determine the mean grain radius. A
3.4 cm £ 3.4 cm strip of ice was melted on a hotplate in the field36, and fed into various
detectors. Aliquots (1.1-m averages) were also collected from this melting device into clean
containers, frozen and shipped to Europe for ion chromatographic analysis37 of major ions
(presented for Termination V). All other measurements were made in laboratories in
Europe after the ice had been shipped frozen from Dome C. dD was determined10 on
meltwater from 55-cm-long sections. This record, still discontinuous for some parts,
should be considered as preliminary. Also, we used a ‘quick’ mode (each sample is
measured twice instead of four times), leading to a typical accuracy of 1.5‰ (1j), whereas
we aim for a final precision of 0.5‰ over the entire core, as currently obtained for EDC96
(the upper 780 m). dD data shown in Fig. 1 correspond to values averaged across seven
successive samples. The current precision and resolution are well adapted for the climatic
interpretation discussed here (Fig. 2), in which we focus on the broad features of Antarctic
climate changes over the past eight climatic cycles.
Dust concentration and size distribution was measured by a 256-channel Coulter
Counter, set to register particles in the size range from 0.7–20 mm (ref. 13). In calculating
mass concentrations, density was taken as 2,500 kg m23. CO2 and CH4 were measured (for
Termination V) by a dry crushing12 and a melt-refreezing extraction technique38,
respectively.
Models used for ice-core dating
Full details of the derivation of the timescale are given in the Supplementary Information.
For the thinning rate computation, we used an ice-flow model39, with prescribed surface
elevation40. It has two poorly known parameters: the melting at the base of the ice
sheet (F), which is the condition for the vertical velocity at the base, and a parameter (m)
for the vertical velocity profile. The vertical strain rate is assumed to be proportional to
1 2 (z/H)(mþ1), where z is the depth and H is the ice thickness. The accumulation rate is
deduced from the dD content of the ice, via the temperature of the inversion layer. This
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conversion involves two further tunable parameters. The last modelling step of the
chronology is the evaluation of the difference between the gas age and the ice age (Dage),
which is required to derive the age scale for the gas measurements. This is derived from a
firn model22. The four poorly known parameters of the models are evaluated through the
use of a small number of chronological controls, through a Monte Carlo inverse
method5,21. The method searches for an optimal agreement, within the limits of the
confidence interval of each assigned age (that is, we use control windows rather than
control points) and using the same rules to define accumulation all along the record. In the
top part of the core, we use the same control points as were used to derive the timescale
(EDC1) recommended for the shallower part of the core41; EDC1 remains the
recommended timescale for this part of the core, and hands over precisely to EDC2 at
800 m. For the bottom part of the core (that is, for the period older than 50 kyr), we used
several age control windows derived by comparison to the stacked marine isotope curve of
Bassinot3, assuming a 4-kyr phase lag. These points are situated at Terminations II
(1,738 m ¼ 131 ^ 6 kyr), III (2,311 m ¼ 245 ^ 6 kyr), IV (2,593 m ¼ 338 ^ 6 kyr), VII
(3,038 m ¼ 626 ^ 6 kyr) and VIII (3,119 m ¼ 717 ^ 6 kyr). Note that the age of identical
events in this EDC2 chronology can differ, over their common parts, from the Vostok and
Dome Fuji chronologies, because of slightly different best-fit parameters in the model.
Received 27 February; accepted 22 April 2004; doi:10.1038/nature02599.
1. Petit, J. R. et al. Climate and atmospheric history of the past 420,000 years from the Vostok ice core,
Antarctica. Nature 399, 429–436 (1999).
2. Imbrie, J. et al. On the structure and origin of major glaciation cycles. 2. The 100,000-year cycle.
Paleoceanography 8, 699–735 (1993).
3. Bassinot, F. C. et al. The astronomical theory of climate and the age of the Brunhes–Matuyama
magnetic reversal. Earth Planet. Sci. Lett. 126, 91–108 (1994).
4. Berger, A. & Loutre, M. F. Insolation values for the climate of the last 10 million years. Quat. Sci. Rev.
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Supplementary Information accompanies the paper on www.nature.com/nature
Acknowledgements We thank the logistics and drilling teams. This work is a contribution to the
European Project for Ice Coring in Antarctica (EPICA), a joint European Science Foundation/
European Commission (EC) scientific programme, funded by the EC and by national
contributions from Belgium, Denmark, France, Germany, Italy, The Netherlands, Norway,
Sweden, Switzerland and the UK.
Competing interests statement The authors declare that they have no competing financial
interests.
Correspondence and requests for materials should be addressed to E.W. ([email protected]).
EPICA community members* (participants are listed alphabetically)
Laurent Augustin1, Carlo Barbante2, Piers R. F. Barnes3, Jean Marc Barnola1, Matthias Bigler4, Emiliano Castellano5, Olivier Cattani6,
Jerome Chappellaz1, Dorthe Dahl-Jensen7, Barbara Delmonte1,8, Gabrielle Dreyfus6, Gael Durand1, Sonia Falourd6, Hubertus Fischer9,
Jacqueline Flückiger4, Margareta E. Hansson10, Philippe Huybrechts9, Gérard Jugie11, Sigfus J. Johnsen7, Jean Jouzel6, Patrik Kaufmann4,
Josef Kipfstuhl9, Fabrice Lambert4, Vladimir Y. Lipenkov12, Geneviève C. Littot3, Antonio Longinelli13, Reginald Lorrain14, Valter Maggi8,
Valerie Masson-Delmotte6, Heinz Miller9, Robert Mulvaney3, Johannes Oerlemans15, Hans Oerter9, Giuseppe Orombelli8, Frederic Parrenin1,6,
David A. Peel3, Jean-Robert Petit1, Dominique Raynaud1, Catherine Ritz1, Urs Ruth9, Jakob Schwander4, Urs Siegenthaler4, Roland Souchez14,
Bernhard Stauffer4, Jorgen Peder Steffensen7, Barbara Stenni16, Thomas F. Stocker4, Ignazio E. Tabacco17, Roberto Udisti5,
Roderik S. W. van de Wal15, Michiel van den Broeke15, Jerome Weiss1, Frank Wilhelms9, Jan-Gunnar Winther18, Eric W. Wolff3 & Mario Zucchelli19*
1, Laboratoire de Glaciologie et Géophysique de l’Environnement (CNRS), BP 96, 38402 St Martin d’Hères Cedex, France; 2, Environmental Sciences Department,
University of Venice, Calle Larga S. Marta, 2137, I-30123 Venice, Italy; 3, British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK; 4, Climate
and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland; 5, Department of Chemistry—Analytical Chemistry
Section, Scientific Pole—University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy; 6, Institut Pierre Simon Laplace/Laboratoire des Sciences
du Climat et de l’Environnement, UMR CEA-CNRS 1572, CE Saclay, Orme des Merisiers, 91191 Gif-Sur-Yvette, France; 7, Niels Bohr Institute for Astronomy, Physics
and Geophysics, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark; 8, University of Milano-Bicocca, Dipartimento di Scienze Ambiente
e Territorio, Piazza della Scienza 1, I-20126 Milan, Italy; 9, Alfred-Wegener-Institute for Polar- und Marine Research (AWI), Postfach 120161, D-27515 Bremerhaven,
Germany; 10, Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91 Stockholm, Sweden; 11, Institut Polaire Français–Paul Emile
Victor (IPEV), BP 75, 29280 Plouzane, France; 12, Arctic and Antarctic Research Institute, 38 Beringa Street, 199397 St Petersburg, Russia; 13, Department of Earth
Sciences, University of Parma, Parco Area delle Scienze 157/A, I-43100 Parma, Italy; 14, 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; 15, Institute for Marine and Atmospheric Research Utrecht
(IMAU), Princetonplein 5, 3584 CC Utrecht, The Netherlands; 16, Department of Geological, Environmental and Marine Sciences, University of Trieste, Via E. Weiss 2,
I-34127 Trieste, Italy; 17, Earth Science Department, University of Milan, Via Cicognara 7, 20129 Milano, Italy; 18, Norwegian Polar Institute, N-9296 Tromsø, Norway;
19, ENEA, CRE Casaccia, PO Box 2400, Via Anguillarese 301, 00060 S. Maria di Galleria (RM), Italy.
*Deceased.
628
©2004 Nature Publishing Group
NATURE | VOL 429 | 10 JUNE 2004 | www.nature.com/nature
Kohnen
Weddell Sea
Dome Fuji
Vostok
Byrd
DomeC
Ross Sea
0km
1,000km
2,000km
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