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Results from the NCAR CSM1.4-carbon model at Bern
Thomas Frölicher
Climate and Environmental Physics,
Physics Institute, University of Bern
1. Modeled changes in oceanic dissolved oxygen
2. Ocean acidification
CARBOOCEAN Core Theme V, Gran Canaria, December 5, 2006
Kim et al, MTS, 1999; Kim et al, GRL, 2002
1996
1979 1969
1932/54
How large are simulated ocean O2 changes in the NCAR
CSM1.4-carbon model over the historical period and the future?
200 240 280 3200
1000
2000
3000
4000
Oxygen [μmol/kg]D
ep
th [m
]
Motivation
Simulations with the NCAR CSM1.4-carbon
Model physics:
• Fully coupled atmosphere(T31)-land-ocean-sea ice model
• low climate sensitivity (T2xCO2 = 1.4 K)
Biogeochemistry model:
• Ocean carbon cycle model: modified OCMIP-2
• prognostic nutrient uptake as function of light, Fe, PO4, temperature
Simulations:
• Forcing: solar + volcanic + GHG + direct sulfate
• prescribed land-use and fossil emissions (historical + SRES A2 + B1)
Heat uptake: Levitus (2005) vs. Model
0-300m
0-3000m
volcano
Sea-to-air O2 flux is increasing
CSM1.4-carbon: 0.25 mol m-2 yr-1
Bopp et al. (2002): 0.35 mol m-2 yr-1
Matear et al. (2000): 0.40 mol m-2 yr-1
positive values: outgassing
B1
A2
O2-flux vs heat flux relationship
2000 – 2100
1820-2000
4.4 nmol J-1
3.2 nmol J-1
Plattner et al. (2002): 5.9 nmol J-1 Bopp et al. (2002): 6.1 nmol J-1 Keeling et al. (2002) : 4.9 nmol J-1 Sarmiento et al. (1998): 6.0 nmol J-1
Modelled vs. observed changes in AOU
Difference between 1990s and 1970s
North Pacific (1990s - 1970s)
Locations of large O2 changes over this centurymaximum decrease of O2
maximum increase of O2
0
-20
-40
<-60
O2 [μmol/kg]>30
24
16
8
0
>4000
3200
2400
1600
800
0
O2 [μmol/kg]
Depth [m]Depth [m]
>4000
3200
2400
1600
800
0
Conclusion
• The global air-to-sea O2 flux is strongly correlated to the global
air-sea heat flux. The O2/heat ratio is smaller than found in
earlier studies.
• The simulated changes are qualitively comparable to the
observations, but regionally too small.
• The oxygen concentration is projected to decrease over this
century, mainly in the North Pacific and the Southern Ocean at
shallow depths.
Projection of supersaturated water
1820 – 2100 (SRES A2)
ΩA > 4: optimal
4 > ΩA > 3: adequate
4 > ΩA > 2: marginal
2> ΩA > 1: low
ΩA < 1: extremely low
Condition for coral calcification
1850 2000 2100
100
96
92
90
0
40
Vo
lum
e [%
]
Posters:
• O2 (T. Frölicher, G.-K. Plattner, F. Joos)
• Ocean acidification (M. Steinacher, T. Frölicher, G.-K. Plattner, F. Joos)
Thanks
Thank you very much for your attention!
Difference 2100 - 1820
DOM Export out of production zone
1820 -2100
∆ ~ 8 %
Phospate in year 2000CSM1.4-carbon World Ocean Atlas (2001)
Atlantic20° W
Pacific167° W
Export Production of POC
CSM1.4-carbon
Laws et al. (2000)
Total: 9.2 Pg C
Total: 11.1 Pg C
∆ ~ 17 %