The study provides a comprehensive overview of analyses enabling definition of a trajectory of values to be taken into account if we are to achieve the goal of net zero GHG emissions by 2050 in France. Among other analysis, a multi-model analysis has been achieved using two different kind of models: macroeconomic models and energy-system models. Finally, the study recommends, for 2030, to put forward a shadow price of €250 per ton of CO2e.. By 2050 it is expected to align with the estimated costs of the enabling technologies required for decarbonization – therefore a cautious range of €600 to €900/ton of CO₂e.