I disagree that it's extremist to believe humanity is facing extinction. It's just not solely from climate change.

The fact of the matter is extinctions tend to happen due to a confluence of things over time. So it won't be like what you see on Hollywood or by a movie timeline, no, but that doesn't equate to it being wrong headed thinking either.

8 billion individuals in a population is relative. All living things have limits. How many crabs disappeared off the forest floor the last two years? An entire generarion of penguin hatchlings was lost last season.

We're standing at the dawn of the 6th mass extinctions event. During all of the others, keystone, apex, and large species didn't make it. Humams are all 3 of those.

It is not extremism or folly to recognize that we're in deep shit as a species. That well most likely be extinct very soon relative to how these things go (geological time).

Astronauts will not be able to repopulate the earth. That IS ridiculous and extremist thinking.