- Количество слайдов: 32
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, two simulations. Positive feedback Larger climate change
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 radiatively active BGCs • Which ones have to be calculated online
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 • 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 (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 change forcing No changes in land-use, fertilizer use, Nitrogen deposition, … Ocean CO 2 and climate change forcing
ORCHIDEE Krinner et al. , 2005 Zaehle et al. , 2006
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 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 mg. N/m 2/yr
Ocean validation Atlantic East Pacific West Pacific Indian
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 2 O flux (mg. N/m 2/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 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 - 1860 Worldwide increase Forests
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 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
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 !!!
Last slide Did we just prove the ice core wrong ?
SRESA 2 – IPSLCM 2 - NPZD SRESA 2 – IPSLCM 4 -PISCES
02 distribution Observations from Levitus (mmol/l) PISCES Model (mmol/l)
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