I don’t think refugee handling says much about our ability to survive. Do you seriously consider refugees as a threat to our existence. If they threaten our life then bring out the guns. Unarmed civilians from abroad are not a threat to civilization.

As for extinctions in the past. You do realize those happened over exceptionally long time by human standards?

And this is animals, not humans which can send things into space and have a profound ability to adapt to changing environment. We can build tunnels systems, artificial climate, cooling systems, any number of things not available to animals.

Even the most dramatic scenarios you sketch out will not happen instantly. Climate systems don’t get jacked up 12 degrees from one day to the next. There is major inertia and we will be able to observe this change and act accordingly to mitigate it. We can build underground systems with cooling. Suits or vehicles with cooling. We can move further north and establish colonies in colder climates.

Sure, we cannot save everyone but that is not what is being argue here. We are arguing about whether we face total extinction, and that proposition is just reckless scaremongering undermining the fight to secure our future. It makes people not take us serious.