Final answer:
The phrase 'How dare you!' in Greta Thunberg's speech serves as an emotional appeal, or pathos, making her argument more persuasive by expressing indignation and moral outrage.
Step-by-step explanation:
The exclamation "How dare you!" in Greta Thunberg's speech is a powerful example of using emotional appeal to make her message more persuasive. This rhetorical strategy, known as pathos, is designed to stir the emotions of the audience, creating a sense of urgency and moral outrage at the state of inaction on climate change.
By expressing her indignation in such a forceful manner, Thunberg effectively conveys her deep frustration and holds her audience accountable for their lack of meaningful action, aiming to compel them to acknowledge the gravity of the situation and act accordingly.