On climate change in general. I don't want to talk unprepared and in a light-hearted manner on subjects I'm not competent enough. All I know is that: a) it's pretty obvious that climate change (warming or cooling in different regions, respectively) is a fact; and b) it's the reasons behind it that are largely unclear and which there's no consensus upon even in scientific circles. Some radical activists (e.g. Greta and co.) are blaming it all on human activity (which I'm generally not likely to disagree with, but I'm not in favour of blaming citizens for using petrol vehicles or taking a flight once a year for their holiday rather than corporations whose carbon footprint per year by far exceeds mine over a whole lifetime); others think it's a factor, but not the only factor; still others claim the cyclical climate changes are brought about by the Earth's shifting away from its axis - i.e. that it's a natural process that's got very little to do with human activity; and yet others suggest the causes are combined.
As for Miss Thunberg in particular... Back when I was 13 at a certain point I decided I wanted to create a time machine to save the life of someone who mattered to me. I figured out to do so I needed some grasp in physics and I even started reading, yay - wasn't easy in itself! Soon enough I realized that I should first finish school, then university, later on probably start a job in the Science Academy, probably then in NASA...and then, perhaps, possibly, working alongside people as competent as myself and even more so - I might actually achieve this great cause...or simply realize that my generation won't live up to it, but at least I'd have tried!
But not attending school is NOT the way. A lot of people do just that, in fact the majority of the planet's population are illiterate, but doing so over some supposedly supreme cause doesn't make it any better. That's what I think.
As for the time machine?... In the end I figured out life is stupid and pointless and the dead are better off staying as they are :).