Video report by ITV News Washington Correspondent Robert Moore
The Swedish teenager who has sparked a youth-driven push for action on climate change has taken part in a protest in Washington.
The 16-year-old has gained international attention by inspiring protests and school strikes demanding immediate action to avert environmental catastrophe.
Young voices tell ITV News what climate crisis message they would like to give to Donald Trump
Her activism has drawn a passionate following of children challenging their elders to take action.
Last month, Greta crossed the Atlantic Ocean in a solar-powered boat, landing in New York on August 28.
She is in Washington for several days of rallies and lobbying efforts in advance of a global climate strike declared for September 20.
She will also address the UN Climate Action Summit in New York on September 23.