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					    European Project for Ice Coring in
Antarctica: (800,000 years of climate and)
   650,000 years of CO2 from ice cores
                Eric Wolff
           (ewwo@bas.ac.uk)
    On behalf of the EPICA community
Bubbles and gases




                    *V
      European Project for Ice Coring
          in Antarctica (EPICA)




                                                          60
                                                           °S
                                 Dronning
                                 Maud Land




                                                  70
                                                    °S
             Berkner
                                                                    Dome C
                                            Dom e F
             Island                                                   75ºS
                                       80
                                        °S                         3233 m asl
                                                                 ~25 kg m-2 yr-1
                       Byrd
                                                Vostok
             Siple Dom e                             Law Dom e
                                               Dom e C
                                      Taylor
                                      Dom e

0km    1,000km         2,000km
            EPICA Dome C status
• Depth reached
  3270 m (bedrock
  3275 m)
• Best estimate of
  useable age ~800
  kyr
• Final 70 m drilled
  in December
  2004
Dome C
Drilling
         -360

                           EPICA
                           Dome C
         -400
D / ‰




         -440
                           Vostok



         -480

                0             200          400        600      800

                                       Age / kyr BP



                    Comparison with Vostok in overlap period
         -370



         -390       WARM
D / ‰




         -410        9 C



         -430


                    COLD
         -450          EPICA Community Members, Nature, 429, 623-628, 2004.

                0                200               400                600     800
                                         Age / kyr before present

Before 450 kyr BP:
•Generally less cold glacial maxima
•Much less warm interglacials
•Higher proportion of time in interglacials
                How does CO2 behave in weak
                       interglacials?
         -370



         -390       WARM
D / ‰




         -410        9 C



         -430


                    COLD
         -450

                0           200             400              600   800
                                  Age / kyr before present
  Weak interglacials have lower CO2




Siegenthaler et al., Science 2005 (EPICA gas consortium)
Weak interglacials have lower CH4




Spahni et al., Science 2005, EPICA gas consortium
            EPICA challenge

• Mudelsee: CO2=f(δDice)
• Monnin: CO2=f(δDice,dust)
• Shackleton: CO2 inverted from marine δ18Obenthic
• Flower: CO2=f(δ13C gradient) (carbonate
  compensation)
• Joos: δDice=f(Tant)=f(CO2,dust,ice volume)
• Matsumoto: CO2=f(δDice,dust,palaeocean proxies,
  insolation)
• Köhler: Box model of C cycle
• Paillard: Conceptual model with thresholds
 EOS Transactions, 86 (38), 341,345, 2005.
                            300
CO2 predicted (Mudelsee)




                            240




                            180

                                              0            200             400                600
                                            300
                 CO2 predicted (Mudelsee)




                                                         The success of approaches using
                                            240
                                                        correlations with Antarctic proxies
                                                         alone implies the dominance of
                                                          Southern Ocean mechanisms?
                                            180

                                                  0         200             400                600



                                            Mudelsee (based only on Vostok data):
                                            pCO2 = 922 + 1.646 * δDt-2000
The CO2-δD relationship stays the same



                            Siegenthaler et al.,
                            Science 2005
          Features to explain
• CO2 increase glacial to interglacial
  (magnitude, timing, shape)
• Different CO2 in different interglacials
• Similar CO2 in each glacial
• Similarity to Antarctic (S. Ocean)
  temperature
• Relationship to other proxies (carbonate,
  dust, sea ice….)
              CO2 data from ice cores

                                                            Vostok
            280
                                                            Taylor Dome
                                                            Dome C
CO2 (ppm)




            240



            200


                  0       20000                      40000                       60000
                                   Age (yr BP)


                          Petit et al., 1999; Indermühle et al., 2000; Monnin et al., 2001
        Glacial CO2 variations
                 50
(ng/cm2/yr)
  Na + flux




                100

                200      A1          A2         A3      A4           1




                                                                            nss-Ca 2+ flux
                                                                             (ng/cm2/yr)
                500
                230                                                  10
   CO 2 (ppm)




                220
                210                                                  100
                                                                     -410
                200
                                                                     -420




                                                                          D (‰)
                190
                                                                     -430
                                                                     -440
                                                                     -450
                 30000    40000             50000            60000
                                  Age (yr BP)
                                                     Röthlisberger et al., GRL, 2004
           Timing during Termination I
                    50
  nss-Ca 2+ flux
   (ng/cm2/yr)



                    20
                    10
                     5
                     2
                     1                                                  -380

                   260                                                  -400




                                                                             D (‰)
Taylor Dome




                   240                                                  -420
 CO 2 (ppm)




                   220                                                  -440
                   200

                   180
                     10000   12000   14000      16000   18000      20000
                                       Age (yr BP)


                                                          Röthlisberger et al., GRL, 2004
  CO2, iron fertilisation and sea ice
   -1
                            1300
    CO2 / ppmv ssNa flux / g m yr
   -2

                            1100
                                     900
                                     700
                                     500
                                     290
                                     300
                                     270
                                                                       Termination V
                                     250
                                     230
                                     210
   -1




                             190
    nssCa flux / g m yr
   -2




                            1000
                                     750
                                     500
                                     250
                                      0
                                      410   415   420            425      430      435
                                                     Age / kyr BP

At Termination V, as at Termination I and others, reduction in dust
flux precedes that in sea ice, with implications for CO2 mechanisms
 Dynamics of the Earth System and
  the Ice-core Record (DESIRE)
• Response to the NERC-INSU joint UK-Fra call
  “to develop a quantitative and predictive
  understanding of the ice-core record of changing
  atmospheric composition”
• 0.8 Myrs, CO2 and CH4
• Synergy with QUEST theme 2, PMIP, etc.
• Passed outline bid stage, now developing full
  proposal (July 27th)
            QUEST-Desire
  Dynamics of the Earth System and the Ice-
                 Core Record
• Need to weave around what is already in Q-
  Deglac and QQ
• Focus on processes not in those, CO2 –
  differences between cycles, CH4 – beyond
  deglaciation
       WP structure 1: 4 strands
•   Methane and “fast” atmospheric chemistry
•   CO2 and the carbon cycle
•   The zoo of interglacials and glacials
•   Coordination
               Current partners
• BAS (Eric Wolff)
• IPSL/LSCE (Pierre Friedlingstein, Pascale Braconnot,
  Gilles Ramstein, Laurent Bopp, Franck Bassinot and
  others)
• Bristol (Sandy Harrison, Paul Valdes, Andy Ridgwell)
• LGGE (Jerome Chappellaz)
• OU (Neil Edwards)
• Reading (David Marshall)
• UEA (Corinne Le Quere)
• Cambridge (Harry Elderfield)
• Exeter (Peter Cox)
 Oliver Wild (Cam), Dudley Shallcross (Bristol)
  Strand 1: CH4 and atmos chem
1.1: Fire modules and integration of methane-related
  components into IPSL-ESM
1.2 13CH4 and hi-res CH4 as constraints on methane
  (CHAMPI-OM)
1.3 13C into FAMOUS
1.4 Prospects for constraints on source and sink for
  methane (atmos chem)
1.5 Wetlands/veg data synthesis at MIS 13/15
    DO8 synthesis by collaboration with QQ
     Strand 2: CO2 and C cycle
2.1 Develop fast model MGV
2.2 SO physics (eddies) and biogeochemistry (effect
  of winds)
2.3 Marine sediment constraints on C cycle
  (including interglacial CaCO 3 in sediments and
  Chatham Rise)
2.4 Dust parameterisation (shape, composition)
2.5 13CO2 in ice
 Strands 3 (models and zoos) & 4
3.1 Time slices MH, EH, LGM (Q-ESM and IPSL-ESM)
3.2 Other interglacials as time slices (FAMOUS and IPSL-
   ESM)
3.3 Short transient DO8 (FAMOUS, IPSL-ESM, MGV)
3.4 Data/model: Compile zoo of ig and g (includes workshops
   about proxies)
3.5 Transient simulations of transitions and igs (GENIE,
   MGV) to explore parameters leading to zoo
4 Coordination
     Under development
• ……….

				
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posted:8/23/2011
language:English
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