Greta Thunberg is a 17-year old environmental activist who has become very famous around the world for her clear and critical message about climate change. Here is part of a speech that she gave to a room-full of adults at the United Nations COP24 Climate Change Conference in Poland in December 2018:
Should teenagers like Greta be telling adults what to do? What do you think?You only talk about moving forward with the same bad ideas that got us into this mess [ie climate change], even when the only sensible thing to do is pull the emergency brake. You are not mature enough to tell it like it is. Even that burden you leave to us children.
You can read more about Greta at EnglishClub's Climate Activist Greta Thunberg page