RESPIC – Paleoclimatic changes in the global carbon cycle
Hubertus Fischer, Felix Fundel, Jochen Schmitt, Birthe Twarloh and Peter Köhler
DEKLIM project RESPIC (young scientist Research group on Earth climate System reconstructions on Polar Ice Cores) Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, email: hufischer@awi-bremerhaven.de
-450 -400 -350
0 800 1600
EDC
δD [°/°°] dust [ppb]
age [yrs BP]
1 5 7 9
11
13 15 17
0 200000 400000 600000 800000
160 200 240 280 320
CO2 [ppmv] Vostok
model
Summary:The goal of RESPIC is the quantification of changes in the global carbon cycle (GCC) in the past. To this end relevant boundary conditions for the GCC have been reconstructed from the new EPICA ice cores and changes in carbon fluxes have been quantified using the new GCC-model BICYCLE. Ice core aerosol records show substantial changes in mineral dust, thus iron input, to the Southern Ocean (SO) parallel to changes in sea level. In contrast, changes in marine biogenic sulfur do not point to a substantial increase in marine sulfur productivity in parallel to a potential iron fertilisation.
Sea ice coverage as revealed in sea salt aerosol doubles for glacial conditions connected to higher SO stratification and reduced gas exchange. In line, BICYCLE reveals a strong effect of SO mixing and carbonate sedimentation/dissolution on atmospheric CO2 while the influence of iron fertilisation is limited to about 20 ppmv. New quantitative information on carbon fluxes can be derived from novell high-precisionδ13CO2 measurements developed within RESPIC which show 0.5 ‰ higher levels during warm marine isotope stage (MIS) 5.5 compared to the penultimate glacial.
The new sublimation GCMS technique allows for 100 % extraction efficien- cy. Only 30 g of ice are required (compared to 200- 1000 g with conventional techniques) for combined δ13C and CO2 measure- ments. An unprecedented accuracy for δ13C of 0.05 ‰ is achieved which is a prerequisite to constrain carbon fluxes.
Based on input data from marine and ice core proxy records, BICYCLE is for the first time able to quantitatively explain the transient glacial/interglacial CO2 change recorded in the Vostok ice core. The first 4 glacial cycles in the EDC record, however, are characterised by reduced CO2 amplitudes.
Major factors are SO deep stratification, carbonate sedimentation(dissolution) and to lesser extent marine
export productivity. SST [°C]
storm activity [mbar²]
GPH 500 mbar [m]
Meterological up- scaling studies of aerosol records using NCEP/NCAR reanalysis data show a strong influence of the Antarctic Dipole Pattern and the Ant- arctic Circumpolar Wave on aerosol transport onto DML.
Wolff et al., EOS,85, 38, 2004
Gersonde et al., Climate Dynamics, 2005 (in press)
EPICA community members, Nature, 429, 2004
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0 100 200 300 400 -58
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0 400 800 1200 1600
0 100 200 300
400 -160
-80 0 80
EDML
δ18O [°/°°] J(ssNa+) [ng/cm²a]
age [yrs BP]
J(nssCa2+) [ng/cm²a]J(SO42-) [ng/cm²a]
1 5.5
sea level [m BP]
EDC
Sea salt fluxes at EDML and EDC are 2-3 times higher in the gla- cial than in the Holo- cene pointing to a two fold increase in sea ice formation. During MIS 5.5 winter sea ice is significantly reduced in line with 2-4 °C warmer temperatures. The mi- neral dust flux in the glacial is up to 12 times higher with highest fluxes during sea level low stands. However, biogenic sulfur fluxes are not (EDC) or only 30 % (EDML) higher.
