Marxism, Islamism, Communism, unsustainable debt, stupid people steeped in liberal philosophies, all could bring about the collapse of society and a massive human die-off. Depending on where you are, that juggernaut is well on its way, and the end of civility could strike anywhere, any time there is an event to provoke it.
Such things have a proven and repeated track record in the 'grand experiment' of doing just that.
The marked and unmarked graves of those not scattered by the elements and scavengers provide mute testimony.
While climate has been known to have ill effect on human populations, warmer climates commonly have led to human expansion and flourishing development. It is the colder climate periods which see humans wracked by famine, hunger, and disease.
Not one thing these people propose has been shown to be beneficial in human history, quite the opposite.
As for species becoming extinct, 99.99% of all species which have ever existed died out, between the Permian and K-T events, huge die offs have occurred, involving the entire planet, and there have been numerous others long before humans became a factor.
I have stated, and will ever maintain, the greatest folly is to throw away the technologies which we have which enable us to overcome the challenges which nature presents, rather than attempt to manipulate nature to do our bidding.
Would someone please explain what it is, what gives this child the knowledge or ability to tell the rest of the Planet how to live?
Sit down, little girl, get a life, learn about life. You're just a poster child for deadly nonsense.