Opening: Although it is never great to yell at an audience, Greta’s line “How dare you?” makes the audience question what she is referring to and pulls the audience in. In fact, due to her anger it makes the whole speech more compelling.
The Use of “You”: Greta makes the audience “you” the target of her criticism. Directly addressing the audience or you, nearly a dozen times in a short amount of times emphasizes her point. Are you really doing anything to help?
Credentials: Some may question her credentials or if she is credible, let alone old enough to speak upon this topic.
On paper, the speech is not very interesting. A large portion of it is made up of data and numbers, but what makes it memorable is that not many 16 year olds would repeatedly scold an audience. She is angry, and she wants people to hear her.