Process oriented evaluation of coupled climate-carbon cycle models Pierre Friedlingstein, IPSL/LSCE, France + contributions from L. Bopp, P. Cadule, C. Jones, S. Piao, and J. Randerson C4MIP in IPCC AR4 Climate projections Climate feedback on Carbon Cycle C4MIP models AOGCMs 730 – 1000 ppm Positive feedback (larger warming), but large uncertainty in simulated atmospheric CO2. Essentially driven by uncertainty in carbon cycle response to climate change At that time, no proper model evaluation C4MIP models Atmospheric CO2 difference (ppm) Change in Land Uptake (GtC) 2.4 – 5.6 °C 2.6 – 4.1 °C Surface Temperature Change (K) Friedlingstein., et al, 2006 Meehl ., et al, 2007 C4MIP in CMIP5 Multiple constrains from observations C4MIP Umbrella Atmospheric CO2 (trends and var.) Leaf Area Index (Greening) Benchmark against 20th century Constrains on processes driving climate-carbon feedback Reduced uncertainty on Climate-carbon cycle gain Compatible emissions Climate projections Ocean Carbon Inventory (trend) Air-Sea CO2 exchange (trends and var.) I-LAMB