Introduc3on to Meteorology. Hervé Le Treut (IPSL UPMC) Ecole Théma3que Michael Ghil La Rochelle 2012

Transcription

1 Introduc3on to Meteorology Hervé Le Treut (IPSL UPMC) Ecole Théma3que Michael Ghil La Rochelle 2012

2 IPSLCM4 IPSL Earth System Model (CM4 / IPSL) Physics Continents Atmosphere Oceans Orchidée LMDZT LMDZ ORCALIM Continental surface Atmospheric Oceanic Circulation Soil and v vé gétation Circulation Sea Ice STOMATE Biochemistry PISCES Biogéochimie et biologie marine Carbon Cycle Chemistry Carbon CH4, COV, Aérosols CO2 INCA Chemistry Gases & Carbon DMS Nutriments Aerosols Marine Salts

3 Des programmes internationaux +WGCM,. + GEO/GCOS,

4 Le premier ensemble de résultats «scénarisant» le futur: GIEC 2001

5 International programs feed the IPCC reports This is the case of CMIP5, the new WCRP Coupled Model Intercomparison Program, which should constitute a strong contribution to the IPCC AR5

6 Greenhouse effect also impacts the vertical distribution of temperatures Z z fin z init T* T

7 Examples of signals Solar Volcanic 20th century response to forcing simulated by PCM GHGs Ozone Direct SO 4 aerosol All Fig. 9.1

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9 Changements observés

10 Diminution de la surface de la banquise Arctique

11 Mesurements from space Altimetry from space Conventional data 1.8 mm/year Observed rise: 3.3 mm/year since Not uniform Yellow/red Blue

12 Variabilité naturelle et action de l homme se superposent

13 Nuages et variations climatiques: Incertitude inchangée pendant les 20 dernières années

14 Uncertainty is largely associated with some key feedbacks. and a few more (soil mositure, state of vegetation, )

15 Impact radiatif des nuages

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19 Illustration des 6 satellites composant l'a-train. De gauche à droite : Aura, Parasol, Calipso, Cloudsat, Aqua, OCO. Crédits : CNES octobre 2004, illustration P. Carril

20 Runaway greenhouse effect

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23 Des changements de pluie importants mais incertains AR4

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25 Climate projections on regional and local scales Performance of current AOGCMs (like those from CMIP3) deteriorate when looking at finer temporal and spatial scales which are needed for many impact assessment studies.

26 All regional studies must be adapted to a specific context

27 Tout le CO2 ne reste pas dans l atmosphère Mais la part qui reste est là pour longtemps Sans le cycle du carbone La nature nous rend un service que certains estiment à 50 Milliards d Euros par an

28 Comment l homme a perturbé les choses ( ) 7.7±0.5 PgC y ±0.1 PgC y -1 47% 1.1±0.7 PgC y PgC y -1 27% Calculated as the residual 26% 2.3±0.4 PgC y -1 Global Carbon Project 2010; 27

29 Human PerturbaFon of the Global Carbon Budget (PgC y -1 ) 7.9± ± ±1.0 (Residual) 4.1± ±0.5 (5 models) Remarkable linearity of sinks response to emissions forcing Land sinks are sensifve to climate, at least on interannual Fme scale 28

30 La végétation: une composante importante du système Increase in soil aridity Extension of the growing season Berthelot et al.,

31 Feedbacks and climate sensifvity definifon In absence of feedback 2xCO2 > 1 C warming Fossil fuel CO2 Volcanoes Solar constant Albedo from Land use Land and ocean carbon sinks Land ice albedo Orbital (a) Charney sensifvity 3 C per 2x CO2 Fig. 1. F λ (b) Long term climate sensifvity 6 C per 2xCO2 30

32 La «grande courroie de transmission» ou circulation thermohalin

33 La circulation océanique est-elle stable? A-t-elle un seul état d équilibre? Illustration à l aide d un modèle très simple La densité de l eau dépend de deux paramètres très différents: est proportionnel à la valeur absolue de: Bilan de sel dans chaque boîte: On pose: Alors: EQUILIBRES MULTIPLES

34 IPCC, WG2

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