Prsentation PowerPoint

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Climate Change Impact on Oceanic Oxygen from
Climate Models
L. Bopp LSCE/IPSL, Paris, France
Motivation Why O2 ? Modelling
Results Mechanisms
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Motivation
Climate Impact on Carbon Fluxes
Results from C4MIP (Friedlingstein et al. 2005,
in press)

• - 11 Climate-Carbon Coupled Models
• (7 GCMs 4 EMICs)
• Same emissions scenario from 1860 to 2100
• 2 simulations each Uncoupled Coupled

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Motivation
Climate Impact on Carbon Fluxes
Ocean carbon sensitivity to climate
A negative impact of climate change on carbon
uptake, But large difference in the amplitude of
the response (5x)
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Motivation
Climate Impact on Carbon Fluxes
How can we test the models ? ? Using Oceanic
Carbon measurements difficult because
climate effect only a second order impact.
First order is the anthopogenic signal ?
Using Oceanic Oxygen measurements impacted
by same processes that Carbon Dyn., Bio. ,
Thermo. but no atmospheric signal in the
ocean / no chemistry the O2 oceanic data-base
is expanding several publications have
reported changes in O2 concentrations over the
last decades and for different basins North
Pacific Emerson, Ono, Wanatabe, Kim South
Pacific Shaffer South Indian Bindoff and
McDougall North Atlantic Garcia Southern
Ocean Matear .
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Motivation
Climate Impact on Oxygen in the Ocean
We need to take into account oxygen fluxes to
constrain the carbon budget
Coupled Biogeochemical / Climate Models have
helped to relate O2 fluxes to heat fluxes
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Modelling Results
Sarmiento et al. 1998 (Nature)
Other Publications Matear et al. 2000, Bopp et
al. 2002, Plattner et al. 2002, .
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Modelling Results
Models show reduced O2 levels with Climate Change
Matear et al. 2000 (2090 Pre Industrial)
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Modelling Results
Models compare reasonably well with observed
changes
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Modelling Results
Models compare reasonably well with observed
changes
Deutsch et al. 2005 90s-80s North Pacific
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Modelling Results
Simulations with the new IPSL coupled model
Observations (WOA 2001)
Modelled
2 x 2-0.5 LMDZ / OPA PISCES
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Modelling Results
Change in O2 concentrations 90s 60s
Simulations with the new IPSL coupled model
South Atlantic
Change in O2 concentrations 2090s 1960s
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Mechanisms of Changes
Global Mean
At the surface SST driven At depth
Stratification driven Biological Impact
opposite direction
Bopp et al. 2002
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Mechanisms of Changes
Matear et al. 2000 2090s-1990s
DO2 D(O2 - r.PO4)
No significant contribution from changes in
export
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Mechanisms of Changes
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2090s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic
Changes in O2 concentration (mmol/m3)
? From 2000 to 2099
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2010s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2020s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2030s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2040s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2050s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2060s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2070s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2080s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability
Changes in SST (C), MLD (m) , Productivity
(gC/m2/yr)
South Atlantic 2090s 2000s
3 C
-3 C
Changes in O2 concentration (mmol/m3)
2 x 2-0.5 LMDZ / OPA PISCES 1860-2100 SRES-A2
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Decadal Variability and GW trend
South Atlantic, 70S, 28W
Mixed Layer Depth in the Weddel Sea, 28E
Oxygen Concentrations 70S, 28E
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Conclusions, Perspectives
Simulated oxygen decreases with global
warming. In places where repeated data exist,
consistency bewteen observed and modeled
trends. Mechanisms Stratification and reduced
ventilation/convection. Decadal variability may
hide global warming impact on O2.