Well she herself was right in one thing: She should still be in school and not radicalized by climate change activists and they should know better not to use children like this.

While yes, climate change is a serious matter, in this addressing to an institution like the UN, it is no use in having an alarmist rhetoric in-front of them and then shaming everyone altogether due to the appealing to authority of her age, emotions and questionable 'facts'.

This doesn't change the opinions of others but promotes fearmongering and by even saying '...change will come whether you like it or not...' sounds pretty much like an eco-facist attitude to me.