1. Regional trends in the land carbon cycle and the underlying mechanisms over the period, 1980-2009 S. Sitch, P. Friedlingstein, G. Bonan, P. Canadell, P. Ciais, P.M. Cox, P. Foster, E. Gloor, K. Goldewijk, C. Huntingford, G. Hurtt, C. D. Jones, S. Piao, I.C. Prentice, C. Le Quere, P. Levy, M. R. Lomas, L. Mercado, B. Mueller, M. Reichstein, S. Running, S. I. Seneviratne, E. Shevliakova, P. Thornton, N. Viovy, G. van der Werf, F. I. Woodward, S. Zaehle, M. Zhao

2. Photosynthesis CO 2 Plant respiration CO 2 Soil respiration (heterotrophic) RH Net ecosystem exchange NEE Terminology Net Primary productivity (NPP)= GPP-Plant respiration RH -NPP Gross Primary productivity (GPP)= Photosynthesis +leaf respiration

3. Total CO 2 emissions Atmosphere Data: NOAA, CDIAC; Le Quéré et al. 2009, Nature-geoscience CO 2 Partitioning (PgC y -1 ) 1960 20101970 1990 2000 1980 10 8 6 4 2 Key Diagnostic of the Carbon Cycle Evolution of the fraction of total emissions that remain in the atmosphere

4. Fate of Anthropogenic CO 2 Emissions (2000-2008) Le Quéré et al. 2009, Nature-geoscience; Canadell et al. 2007, PNAS, updated 1.4 PgC y -1 + 7.7 PgC y -1 3.0 PgC y -1 29% 4.1 PgC y -1 45% 26% 2.3 PgC y -1

5. Modelled Natural CO 2 Sinks Le Quéré et al. 2009, Nature-geoscience

6. Global Annual Budget Regional Trends in Land C-Sinks (Trendy) Compare DGVM-based estimates with other evidence - Satellite derived data - Fluxtower data - Atmospheric Monitoring Stations Regional Trends in C-sinks and Annual Global Budget

7. GCP- Land trends: modelling protocol Contact: Stephen Sitch (s.sitch@leeds.ac.uk) & Pierre Friedlingstein (pierre.friedlingstein@bristol.ac.uk)s.sitch@leeds.ac.ukpierre.friedlingstein@bristol.ac.uk Goal: To investigate the trends in NEE over the period 1980-2009 Participating models JULES, LPX, ORCHIDEE, O-CN, HyLand, SDGVM, NCAR CLM4, GFDL/Princeton Model simulations The models will be forced over the 1860-2009 period with changing CO 2, climate (CRU/NCEP) and land use: S1: CO2 only S2: CO2 and climate S3 (optional): CO2, climate and land use Trendy Protocol

8. Land Source trend positive NPP trend < positive RESP trend negative NPP trend < negative RESP trend negative NPP trend, positive RESP trend Land Sink trend positive NPP trend > positive RESP trend negative NPP trend > negative RESP trend positive NPP trend, negative RESP trend Trends in Land Processes

9. Land Sink trend positive NPP trend > positive RESP trend negative NPP trend > negative RESP trend positive NPP trend, negative RESP trend Land Source trend positive NPP trend < positive RESP trend negative NPP trend < negative RESP trend negative NPP trend, positive RESP trend Climatic Drivers of Trends in Land Processes

10. B. Mueller, ETH Zurich Satellite Evidence: Trends in Soil Moisture

11. Remarkable Similarity between NPP evolution from DGVMs

12. Global NPP explains most of the NEE variability

13. DGVM sink vs MODIS-NPP) M Zhao

14. Alternative Upscaling Approaches Multidimensional flux patterns... Color: GPP... models to be cross-evaluated against. Reichstein remote sensing of CO 2 Temporal scale Spatial scale [km] hour day week month year decade century local 0.1 1 10 100 1000 10 000 global forest inventory plot CountriesEU plot/site tall tower obser- vatories Forest/soil inventories Eddy covariance towers Landsurface remote sensing

15. JJA Stippled areas > 90% of the models agree in the sign of the change http://www.ipcc.ch/ Future Precipitation Changes (Summer Droughts?)

16. Use set-up to produce global/regional annual C-budgets Drought may be an important driver of the present-day trends in the land carbon cycle Climate Models Project Summer Drought in Continental Regions Drought may be an important driver of the future trends in the land carbon cycle Critical to understand Ecosystem Response to Drought for future Earth System feedbacks Summary