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N2O-Climate feedback
P.Friedlingstein, L. Bopp, S. Zaehle,
P. Cadule and A. Friend
IPSL/LSCE
Climate carbon cycle feedback
Positivefeedback
11 coupled climate carbon cycle models, same forcing in emissions, two simulations.
Largerclimate change
Radiative forcing
Climate - Biogeochemical cycle feedback ?
: Anthropogenic but also Natural sources/sinks
Feedback estimate
• What are the feedbacks between climate and other major radiatively active BGCs
• Which ones have to be calculated online-0.4
-0.2
0
0.2
0.4
CO2 CH4 N2O
? ?
Climate-BGC gain
Atmospheric [N2O] *
IPCC, TAR, 2001(*) In the following, whenever I say CO2, I mean N2O
N2O Emissions
IPCC, TAR, 2001
N2O
• What are the potential changes in natural N2O emissions due to climate change
Methodology
• Estimate land and ocean N2O emissions
– Historical and Future evolution (SRES-A2)– Use of IPSL AOGCM climate fields to drive
• ORCHIDEE land BGC model• PISCES ocean BGC model
• Estimate atmospheric change due to climate-N2O emission feedback
Experimental design
• Landa) CO2 forcing only
b) CO2 and climate change forcing
No changes in land-use, fertilizer use, Nitrogen deposition,…
Ocean
CO2 and climate change forcing
Climate forcing
ORCHIDEE
Krinner et al., 2005Zaehle et al., 2006
Some validation
PS Sönke will buy more validation data at any price !
PISCES
PO43-
Diatoms
MicroZoo
P.O.M.
D.O.M
Si
FeNano-phyto
Meso Zoo
NO3-
NH4+
Small Large
N2O Parametrization from Suntharalingham et al., 2002
J_N2O = f(O2 consumption, O2 concentration)
Aumont et al., 2003
PISCES Model
N2O Flux mgN/m2/yr
ObservationsNevison et al. 2005 :
Ocean validation
Atlantic
East Pacific
West Pacific
Indian
Ocean validation
Atmospheric pCO2 (ppm)
Primary Productivity (GtC/yr)
N2O Flux (TgN/yr)
Ocean story
Change inO2 concentration (mol/l)
Change inN2O flux (mgN/m2/yr)
2100 - 1860
Ocean story
Land story
N2O Flux (TgN/yr)
Land story
Change inN2O flux (gN/m2/yr)
2100 - 1860
Grassland and cropland
Forests
Grassland and cropland
Forests
Most of the change occurs in temperate
grasslands and croplands
Land story
Relative change inN2O flux (%)
2100 - 1860
Grassland and cropland
ForestsWorldwide increase
Atmospheric N2O Budget
ATM
ONEMI
t
ON
22
ON2
EMIWhere
ATM
is the change in atmosphericN2O concentration since PI.
is the change in natural emissions since PI
is the life-time of N2O in the atmosphere
ocean
land
sink
source
10 ppb decrease -0.03 W/m2
Atmospheric N2O BudgetEmissions
Atm. Source/Sink
Atm. Concentration
EMI
EMI
5.5
3.5
1.5T
gN/y
r
0.
-0.2
ppb
275
270
265
ppb
But… key role of N inputs
Conclusions
• Climate change alone may induces– decrease of oceanic emissions– increase of continental emissions
• Overall effect : negative feedback– Small (10 ppb decrease) relative to future
anthropogenic scenarios (+ 200 ppb)
• Future continental emissions largely driven by N dep, Nfert.
• However …
N2O G-IG changes
Positive feedback !!!
Last slide
Did we just prove the ice core wrong ?
SRESA2 – IPSLCM2 - NPZD SRESA2 – IPSLCM4 -PISCES
Observations from Levitus(mol/l)
PISCES Model(mol/l)
02 distribution
Climate forcing
Land story
Change inN2O flux (gN/m2/yr)
2100 - 1860
Most of the change occurs in temperate
grasslands and croplands
CO2 alone
Climate and CO2
Climate effect