Greta Thunberg, Swedish high school student leading global campaign against fossil fuels: Greta Thunberg has excoriated world leaders for their “betrayal” of young people through their inertia over the climate crisis at a United Nations summit that failed to deliver ambitious new commitments to address dangerous global heating.In a stinging speech on Monday, the teenage Swedish climate activist told governments that “you are still not mature enough to tell it like it is. You are failing us. But the young people are starting to understand your betrayal.” Comments by energy and environmental specialists around the world have been added.