New York (AP) - The climate activist Greta Thunberg has called on the heads of state and government of the world at the UN climate summit with an emotional and urgent appeal for more commitment to climate change. "How dare you steal my dreams and my childhood with your empty words?" Said Thunberg in New York, with tears in his eyes. "We're at the beginning of a mass extinction and all you can talk about is money and the tales of a never ending economic growth - how dare you?"