[BucketsMcG]

Humanity goes extinct if sustainability and climate change don't matter. And so does a lot else. We've already ensured through our actions to date that what remains of our time on this earth will be miserable, but we might still stand some chance of not completely ruining the place.

A 33% reduction in the population of one country is a tiny step in the right direction, but still far short of making a significant difference.

[mensetmanusman]

Humanity still goes extinct if climate change mattered due to the lifetime of earth/sun.

[toss1]

That is not at all necessarily true. We have another 5 billion years or so before the sun exhausts it's hydrogen and starts substantially changing.

Applying even current levels of intelligence and knowledge (nevermind projecting even hints of the growth rates over the last ~10K years since agriculture, writing, etc. started), that is more than sufficient to develop resources for interplanetary and interstellar travel.