Greta: 'If you fail us, we will never forgive you'
Greta Thunberg has told world leaders that "the eyes of all future generations are upon you" during a powerful speech in the United States.
She addressed them at the United Nations Climate Action Summit in New York.
World leaders, including UK Prime Minister Boris Johnson, are there to discuss the issue of climate change and what can be done about it.
She had some strong words for them.