Rinnovabili e/o nucleare. Come l'energia può combattere i cambiamenti climatici - The new point of view in climatology, that tells us of abrupt climate change (2002), has compelled the world scientific community to ask the G8 of Gleneagles (2005) for a "prompt action" in order to face the dramatic link energy/climate change properly. This request has already become a matter of policy decisions, see the "three 20%" stated by European Union as the objective at 2020 and the 150 billions of dollars program of Obama. What’s the role, in this perspective, of renewable energy sources and nuclear one? The present paper shows the inconsistency of the "nuclear renaissance" and the incompatibility, specially for our country, between the nuclear choice launched by the Italian government and the 2020 EU objective, mainly but not only for economical reasons.