"You have stolen my dreams and my childhood with your empty words," Greta Thunberg said at a U.N.
Climate change summit on Monday (September 23), admonishing adults for not doing enough to protect the environment.
"How dare you," Thunberg repeated during her speech.
Days after millions of young people took to the streets worldwide to demand emergency action on climate change, leaders gathered at the United Nations.
They're trying to generate momentum to curb carbon emissions.
Secretary-General Antonio Guterres has warned governments that they would have to offer action plans to qualify to speak at the summit, which is aimed at boosting the 2015 Paris Agreement to combat global warming.