Twenty years ago, at the original Rio Earth Summit, Severn Suzuki, a 12-year-old from Canada, became "the girl who silenced the world for six minutes" by giving a sobering, kick-ass speech to the assembled delegates. You're going to want to watch it:
This is like the climax to the best YA novel of all time (discounting ones with magic and vampires). Really, there's nothing like an incredibly poised middle-schooler speaking up for her beliefs and making powerful adults feel silly. As Suzuki said then:
At school, even in kindergarten, you teach us how to behave in the world. You teach us to not to fight with others, to work things out, to respect others and to clean up our mess, not to hurt other creatures, to share, not be greedy. Then, why do you go out and do the things you tell us not to do?