1. N2O-Climate feedback P.Friedlingstein, L. Bopp, S. Zaehle, P. Cadule and A. Friend IPSL/LSCE

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

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

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

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

6. N 2 O Emissions IPCC, TAR, 2001

7. N2ON2O What are the potential changes in natural N 2 O emissions due to climate change

8. Methodology Estimate land and ocean N 2 O 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-N 2 O emission feedback

9. 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

10. Climate forcing

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

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

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

14. PISCES Model N 2 O Flux mgN/m2/yr Observations Nevison et al. 2005 : Ocean validation

15. Atlantic East Pacific West Pacific Indian Ocean validation

16. Atmospheric pCO2 (ppm) Primary Productivity (GtC/yr) N 2 O Flux (TgN/yr) Ocean story

17. Change in O2 concentration (  mol/l) Change in N 2 O flux (mgN/m2/yr) 2100 - 1860 Ocean story

18. Land story N 2 O Flux (TgN/yr)

19. Land story Change in N 2 O flux (gN/m2/yr) 2100 - 1860 Grassland and cropland Forests Grassland and cropland Forests Most of the change occurs in temperate grasslands and croplands

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

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

22. ocean land sink source 10 ppb decrease -0.03 W/m 2 Atmospheric N 2 O Budget Emissions Atm. Source/Sink Atm. Concentration 5.5 3.5 1.5 TgN/yr 0. -0.2 ppb 275 270 265 ppb

23. But… key role of N inputs

24. 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 …

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

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

27. SRESA2 – IPSLCM2 - NPZDSRESA2 – IPSLCM4 -PISCES

28. Observations from Levitus (  mol/l) PISCES Model (  mol/l) 0 2 distribution

31. Climate forcing

32. Land story Change in N 2 O flux (gN/m2/yr) 2100 - 1860 Most of the change occurs in temperate grasslands and croplands CO 2 alone Climate and CO 2 Climate effect