extending the history of atmospheric ch 4 concentrations back to 650 kyr ago

Extending the history of atmospheric CHExtending the history of atmospheric CH44

concentrations back to 650 kyr agoconcentrations back to 650 kyr ago

European Geosciences Union  European Geosciences Union  General Assembly 2005General Assembly 2005

Vienna, Austria, 24 - 29 April 2005Vienna, Austria, 24 - 29 April 2005

R. Spahni1, J. Chappellaz2, G. Hausammann1, L. Loulergue2,T. F. Stocker1, J. Jouzel3

(1) Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland(2) Laboratoire de Glaciologie et Géophysique de l’Environnement (LGGE, CNRS-UJF), Grenoble, France

(3) Laboratoire des Sciences du Climat et de l‘Environnement (UMR CEA-CNRS), CE Saclay, Gif-Sur-Yvette, France(spahni@climate.unibe.ch)

A. Short introduction

B. Available CH4 records (Vostok, Dome C)

C. New CH4 measurements for MIS 12 to 16 and first interpretations

OutlookOutlook

Reconstructing atmospheric CHReconstructing atmospheric CH44

• ice sample size: ~40g

• melt and refreeze technique for the extraction of the air

• analysis by gas chromatography

• reproducibility of ~10ppbv

-480

-440

-400

-360

D (

ice)

[‰]

0 100,000 200,000 300,000 400,000 500,000 600,000

ED C 2 age [years BP ]

400

500

600

700

Dom

e C

CH

4 [p

pbv]

400

500

600

700

Vos

tok

mat

ched

to E

DC

2 C

H4 [p

pbv]

EPICA Dome C & Vostok ice coresEPICA Dome C & Vostok ice cores

Delmotte et al. (2004)Delmotte et al. (2004)

Petit et al. (1999)Petit et al. (1999)

EPICA Community EPICA Community Members (2004)Members (2004)

-480

-440

-400

-360

D (

ice)

[‰]

0 100,000 200,000 300,000 400,000 500,000 600,000

ED C 2 age [years BP ]

400

500

600

700

Dom

e C

CH

4 [p

pbv]

400

500

600

700

Vos

tok

mat

ched

to E

DC

2 C

H4 [p

pbv]

EPICA Dome C & Vostok ice coresEPICA Dome C & Vostok ice cores

New data!New data!

Climate shiftClimate shift

-460

-440

-420

-400

-380

-360

Dom

e C

D

(ic

e) [‰

]

0 100,000 200,000 300,000 400,000 500,000 600,000

ED C 2 age [years BP ]

400

500

600

700

Dom

e C

& V

osto

k C

H4 [p

pbv]

Climate shiftClimate shift

-460

-440

-420

-400

-380

-360

Dom

e C

D

(ic

e) [‰

]

0 100,000 200,000 300,000 400,000 500,000 600,000

ED C 2 age [years BP ]

400

500

600

700

Dom

e C

& V

osto

k C

H4 [p

pbv]

?

Measured CHMeasured CH44 data data

-440

-420

-400

-380

-360

D (

ice)

[‰]

440,000 480,000 520,000 560,000 600,000 640,000

age [yr BP]

300

400

500

600

700

CH

4 [p

pbv

]

BernG renoble

11 13

12 14 16

15.315.1

15.2

-440

-420

-400

-380

-360

D (

ice)

[‰]

440,000 480,000 520,000 560,000 600,000 640,000

age [yr BP]

300

400

500

600

700

CH

4 [p

pbv

]

11 13

12 14 16

15.315.1

15.2

Missing Termination from MIS 14 to 13Missing Termination from MIS 14 to 13

Last Glacial Period MIS 3Last Glacial Period MIS 3

Huber et al. (submitted 2004)Huber et al. (submitted 2004)

420,000 440,000 460,000 480,000 500,000

ED C 2 age [yr BP ]

400

500

600

700

CH

4 [p

pbv

]

100

80

60

40

20

0

% IR

D

4

3 .6

3.2

2.8

2.4

bent

hic

18 O

[‰]

4 .0

3.0

2.0

1.0

plan

cton

ic

18O

[‰]

- - - N orth A tlantic m arine core 980

- EPIC A D om e C ice core

11 1312

Oppo et al. (1998)Oppo et al. (1998)McManus et al. (1999)McManus et al. (1999)

Millennial Scale VariationsMillennial Scale Variations

Conclusions for MIS 16 to 12Conclusions for MIS 16 to 12

• Consistent with the temperature proxy D, mean CH4 levels were lower during interglacials 15 and 13 than in the consecutive interglacials 11, 9, 7, 5 and 1.

• High correlation to Antarctic temperature on glacial- interglacial time scales

• the climatic transition from MIS 14 to 13 is saw tooth shaped instead of showing a clear termination

Thank you for your attention

• rapid CH4 increases are observed millennial scale variations similar to the Last Glacial Period seem to be a robust feature of our climate system