The

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The CO2 paradox of MIS 11 A consideration for
understanding Quaternary CO2 variability
Stephen Barker Cardiff University NIEeS GENIE
workshop, June 2006
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Siegenthaler et al., 2005
Petit et al., 1999
to understand atmospheric CO2 variability we must
understand changes in marine carbonate chemistry
(whole ocean shifts, biogeochemistry, sediment
interaction)
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Marine Carbonate dissolution during the
Mid-Brunhes
Pacific Ocean
Farrell and Prell, 1989
MBDI
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Marine Carbonate dissolution during the
Mid-Brunhes
Indian Ocean
MBDI
Bassinot et al., 1994
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Marine Carbonate dissolution during the
Mid-Brunhes
Atlantic
MBDI
Crowley, 1985
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different proxies, oceans, water depths...
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The CO2 paradox of MIS 11
In general Intensification of CaCO3 dissolution
during MIS 11 (Mid-Brunhes) requires lower mean
ocean saturation, ? CO3 Mean ocean CO3 is
inversely related to atmospheric CO2
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Possible causes of the MBDI

• Changes in ocean circulation
• Basin / shelf fractionation - coral reef growth
  (Droxler and others)
• Changes in weathering flux (Bassinot et al.,
  1994)
• Change in pelagic carbonate production

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Global proliferation of the Gephyrocapsa
coccolithophore during the Mid-Brunhes
2mm
Gephyrocapsa oceanica
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Modern day Emiliania huxleyi

• Climatically relevant
• Ocean albedo
• Cloud albedo (DMS)
• CO2 feedbacks

http//www.noc.soton.ac.uk/soes/staff/tt/eh/index.
html http//seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/S
EAWIFS_GALLERY.html
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Global proliferation of the Gephyrocapsa
coccolithophore
Bauman and Freitag, 2004
Bassinot et al., 1994
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Global CaCO3 accumulation changes
all g/cm2/ka
Steady state concept
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Considerations for modelling atmospheric CO2

• Sediment interaction , weathering, coral reefs
• Division of plankton groups
• Increased inorganic pump?
• Ballasting effect (organic pump)? Rain
  ratios... (export, benthic)
• Information about dissolution fluxes,
  accumulation changes, deep water chemistry

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Box model results
(1) Increase CaCO3 Corg production ratio
(CaCO3R) by 50 (2) Increase CaCO3R and primary
(Corg) production in high latitudes (3)
Increase CaCO3R and Corg export by enhanced
ballasting
Barker et al., in review
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The Mid-Brunhes Dissolution Interval a global
phenomenon
1. ODP 982 2. Helmke and Bauch, 2002 3. Droxler
et al., 1988 4. Crowley, 1985 5. Hodell et al.,
2000 Becquey and Gersonde, 2002 6. Forsberg et
al., 2003 7. Farrell and Prell, 1989 LaMontagne
et al., 1996 8. Le et al., 1995, 9. Almogi-Labin
et al., 1998 10. Bassinot et al., 1994 Peterson
and Prell, 1985 Droxler et al., 1990 Cullen and
Droxler, 1990 11. Wu et al., 1991 12. Haddad et
al., 1993
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Records of d13C
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Records of d13C
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Records of d13C
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Records of d13C
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Coccolith Sr/Ca as an indicator of
coccolithophorid calcification and growth rate
Barker et al., in review