The EPICA ice core from Dronning Maud Land as an archive for climate variations by using stable isotope measurements

The EPICA ice core from Dronning Maud Land as an archive for climate

variations by using stable isotope measurements

3^rdMalaysian Int. Seminar on Antarctica (MISA3), March 21-23 2007, Kota Kinabalu

H. Oerter, H, Meyer and EPICA team Hans.Oerter@awi.d e

• Introduction: Overview EPICA and drilling

• The δ

O - depth profile

• Dating and upstream corrections

• δ

O Time series

• Comparison with Dome C, Dome F

• Comparison with NGRIP D/0 events

• Conclusions

Kohnen

Dome Fuji

South Pole Dome A

Vostok Dome C Taylor D.

Siple D.

Byrd Siple St.

Dyer Pl.

B15

Berkner Is.

Plat. Rem.

Law Dome EPICA-DML,

Depth 2774 m, >300 kyrs

Ice core locations

in Antarctica

>900 kyrs ?

EPICA, Depth 3270 m, 890 kyrs

Russ., F, US, Depth 3700m, 420 kyrs

Kohnen (2892 m a.s.l.) Dome C (3233 m a.s.l.)

Layout: h. oerter/w.rack, ‚awi

Talos Dome

Basic data of the EPICA DML drilling site Basic data of the EPICA DML drilling site

Kohnen station, Dronning Maud Land

Kohnen station, Drill trench

Foto: AWI / oerter Foto: AWI / Traufetter

Area: Dronning Maud Land

Station: Kohnen Station

Co-ordinates: 75°00'06"S; 00°04'04"E

Altitude: 2,892 m (WGS84)

Mean annual surface temperature: -44.6°C (10 m depth temperature)

Mean annual accumulation rate: 64.0 0.5 kg^.m^-2.a^-1 (for last 1000 and last 4000 years)

Surface velocity: 0.74 m a^-1 Measured ice thickness: 2,782 10 m Notation of ice core: EDML

Drilling depth 2774 m 2774 m

January 17, 2006

The EPICA Dronning Maud Land ice core (EDML)

¾Drilled in the Atlantic sector of the Southern Ocean

Direct counterpart of the Greenland ice cores

¾Analysed over one glacial cycle. Bedrock reached in the 2005/06 season, more glacial cycles waiting

¾2-3 times higher accumulation rate than other deep ice cores from the East Antarctic plateau Higher resolution for the last glacial, improved CH₄ synchronisation

Layout: H. Fischer, AWI, 2006

The end ... a little bit unexpected !

Foto: S. Kipfstuhl, AWI, 2006

Drilling into the refrozen water:

only ca. 30 cm

The end of drilling meteoric ice - refrozen water

fotos: h. oerter, 2005/06

Observation of S. Kipfstuhl:

The whitish ice is refrozen meltwater. It is extremely fine grained and contains a lot of air or gas. From the physical conditions at the bottom (200-250 bar) part of this ice may be formed as hydrates. The amount of drilling chips is low as clear fragments (former chips) can hardly be detected in the microphotographs.

About 15 % drilling fluid is entrapped in this ice.

Resolution EDML > EDC

ca. 2000 m / 80,000 years

EDML EDC

Final depth: 2774 m

0.5m samples 1m samples

EPICA Community Members, Nature(2006)

MIS 3

MIS 3

-55 -51 -47 -43 -39

0 50000 100000 150000

-150 -100 -50 0 50

-100 0 100 200 300 δ18O [°/°°]

age [yr BP]

∆sea level [m]

∆altitude of deposition [m]

The EDML ice core

δ¹⁸O so far in 0.5 m resolution (<30 yr for the last 50,000 years)

as measured

sea level corrected

sealevel & upstream corrected

2) Correction for upstream and altitude effects using 3D flow model (from Huybrechts & Rybak, AWI) MIS5.5

150 km EPICA Community Members, Nature (2006)

MIS5.5

1) Correction for δ¹⁸O changes in sea water

MIS5.5

The EPICA Dronning Maud Land ice core (EDML)

Very high covariance between East Antarctic records

More details in EDML with each wiggle corresponding to a DO event!?

-63 -58 -53 -48 -43 -38

0 50000 100000 150000

-530 -490 -450 -410 -370 -330 -52 -48 -44 -40 -36

-48 -44 -40 -36 -32

EDML

δ18Ocorr [°/°°]

age [yrs BP]

MIS1 MIS5.5

δDcorr [°/°° ]Tsurf [°C]

DO1

23456789101112 13

141516 17

18 1920 21

22 2324 25

Dome F EDC

δ18O

[ °/] °°

NGRIP

Watanabe et al.,nature, (2003) EPICA community members,nature(2004) NGRIP members,nature(2004)

9-10°C

EPICA Community Members, Nature (2006) MIS3

25k

Every DO event has a counterpart in an Antarctic Isotope Maximum (AIM) Antarctic warming starts in the stadial, the cooling in the interstadial One-to-one bipolar seesaw pattern for each event

NGRIP - EDML

synchronisa- tion

EDML Delta 18-O ()

Alter auf neuer NGRIP Zeitskala (kyrs BP)

NGRIP Delta 18-O ()

3 4 5 6 7

DO 8 9 10

11

DO 12

NGRIP

EDML

nature

AIM 3 4 5 6 7

AIM 8

9 10 11

AIM 12 4.1

Age on new NGRIP age scale (kyrs BP)

MIS 3

EPICA Community Members, Nature (2006)

The bipolar seesaw concept

Reduced AMOC:

Southern Ocean warms

Increased AMOC:

Southern Ocean cools

X

Southern

Ocean Atlantic Ocean

X

Stadial:

ACC AMOC

Interstadial:

Stocker & Johnsen, 2003

Bipolar seesaw (thermal and freshwater) also found in coupled GCMs (Knutti et al., 2004)

Stocker & Johnsen, Paleoceanography (2003)

Layout: H. Fischer, AWI, 2006

Bipolar seesaw coupling

0.0 1.0 2.0 3.0

12

11 10 9

8

7

6 5

4.1 4

3

500 1000 1500 2000

duration [yr]

∆Tsurf [°C]

b

NGRIP stadial duration (yr)

E D M L ∆ T

( ° C )

1.0 2.0

Duration of stadials in the North are correlated with amplitude of AIMs or temperature change in the South, resp.

EPICA Community Members, Nature (2006)

Conclusions

¾EDML (and high resolution records of EDC) show millenial climate variability during MIS3.

¾CH₄synchronisation of EDML and NorthGRIP allows for a one-to-one assignment of each Antarctic Isotope Maximum (AIM) to a Dansgaard- Oeschger (DO) event in the North Önew nomenclature

¾The amplitude of the AIMs is linearly coupled to the duration of stadials in the North. This implies a direct bipolar seesaw coupling via the Atlantic meridional circulation

¾The constant linear relationship indicates a constant oceanic heat flux, thus, a rather uniform turnover rate for all stadials

Thank you !