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N 2 O-Climate feedback P. Friedlingstein, L. Bopp, S. Zaehle, P. Cadule and A. N 2 O-Climate feedback P. Friedlingstein, L. Bopp, S. Zaehle, P. Cadule and A. Friend IPSL/LSCE

Climate carbon cycle feedback 11 coupled climate carbon cycle models, same forcing in emissions, Climate carbon cycle feedback 11 coupled climate carbon cycle models, same forcing in emissions, two simulations. Positive feedback Larger climate change

Radiative forcing : Anthropogenic but also Natural sources/sinks Climate - Biogeochemical cycle feedback ? Radiative forcing : Anthropogenic but also Natural sources/sinks Climate - Biogeochemical cycle feedback ?

Feedback estimate Climate-BGC gain • What are the feedbacks between climate and other major Feedback estimate Climate-BGC gain • What are the feedbacks between climate and other major radiatively active BGCs • Which ones have to be calculated online

Atmospheric [N 2 O] * (*) In the following, whenever I say CO 2, Atmospheric [N 2 O] * (*) In the following, whenever I say CO 2, I mean N 2 O IPCC, TAR, 2001

N 2 O Emissions IPCC, TAR, 2001 N 2 O Emissions IPCC, TAR, 2001

N 2 O • What are the potential changes in natural N 2 O N 2 O • What are the potential changes in natural N 2 O emissions due to climate change

Methodology • Estimate land ocean N 2 O emissions – Historical and Future evolution Methodology • Estimate land ocean N 2 O emissions – Historical and Future evolution (SRES-A 2) – Use of IPSL AOGCM climate fields to drive • ORCHIDEE land BGC model • PISCES ocean BGC model • Estimate atmospheric change due to climate-N 2 O emission feedback

Experimental design • Land a) CO 2 forcing only b) CO 2 and climate Experimental design • Land a) CO 2 forcing only b) CO 2 and climate change forcing No changes in land-use, fertilizer use, Nitrogen deposition, … Ocean CO 2 and climate change forcing

Climate forcing Climate forcing

ORCHIDEE Krinner et al. , 2005 Zaehle et al. , 2006 ORCHIDEE Krinner et al. , 2005 Zaehle et al. , 2006

Some validation PS Sönke will buy more validation data at any price ! Some validation PS Sönke will buy more validation data at any price !

N 2 O Parametrization from Suntharalingham et al. , 2002 PISCES NH 4+ NO N 2 O Parametrization from Suntharalingham et al. , 2002 PISCES NH 4+ NO 3 - PO 43 - Diatoms Si Nano-phyto Fe Micro. Zoo D. O. M Meso Zoo P. O. M. Small Large Aumont et al. , 2003 J_N 2 O = f(O 2 consumption, O 2 concentration)

Ocean validation Observations Nevison et al. 2005 : PISCES Model N 2 O Flux Ocean validation Observations Nevison et al. 2005 : PISCES Model N 2 O Flux mg. N/m 2/yr

Ocean validation Atlantic East Pacific West Pacific Indian Ocean validation Atlantic East Pacific West Pacific Indian

Ocean story Atmospheric p. CO 2 (ppm) Primary Productivity (Gt. C/yr) N 2 O Ocean story Atmospheric p. CO 2 (ppm) Primary Productivity (Gt. C/yr) N 2 O Flux (Tg. N/yr)

Ocean story 2100 - 1860 Change in O 2 concentration (mmol/l) Change in N Ocean story 2100 - 1860 Change in O 2 concentration (mmol/l) Change in N 2 O flux (mg. N/m 2/yr)

Land story N 2 O Flux (Tg. N/yr) Land story N 2 O Flux (Tg. N/yr)

Land story Change in N 2 O flux (g. N/m 2/yr) Grassland and cropland Land story Change in N 2 O flux (g. N/m 2/yr) Grassland and cropland 2100 - 1860 Most of the change occurs in temperate grasslands and croplands Forests

Land story Grassland cropland Relative change in N 2 O flux (%) 2100 - Land story Grassland cropland Relative change in N 2 O flux (%) 2100 - 1860 Worldwide increase Forests

Atmospheric N 2 O Budget Where is the change in atmospheric. N 2 O Atmospheric N 2 O Budget Where is the change in atmospheric. N 2 O concentration since PI. is the change in natural emissions since PI is the life-time of N 2 O in the atmosphere

Atmospheric N 2 O Budget Emissions land Tg. N/yr ocean 5. 5 3. 5 Atmospheric N 2 O Budget Emissions land Tg. N/yr ocean 5. 5 3. 5 1. 5 source 0. -0. 2 Atm. Concentration 275 ppb sink ppb Atm. Source/Sink 270 265 10 ppb decrease -0. 03 W/m 2

But… key role of N inputs But… key role of N inputs

Conclusions • Climate change alone may induces – decrease of oceanic emissions – increase 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 …

N 2 O G-IG changes Positive feedback !!! N 2 O G-IG changes Positive feedback !!!

Last slide Did we just prove the ice core wrong ? Last slide Did we just prove the ice core wrong ?

SRESA 2 – IPSLCM 2 - NPZD SRESA 2 – IPSLCM 4 -PISCES SRESA 2 – IPSLCM 2 - NPZD SRESA 2 – IPSLCM 4 -PISCES

02 distribution Observations from Levitus (mmol/l) PISCES Model (mmol/l) 02 distribution Observations from Levitus (mmol/l) PISCES Model (mmol/l)

Climate forcing Climate forcing

Land story Climate and CO 2 Change in N 2 O flux (g. N/m Land story Climate and CO 2 Change in N 2 O flux (g. N/m 2/yr) 2100 - 1860 CO 2 alone Most of the change occurs in temperate grasslands and croplands Climate effect