Even if we manage to get human carbon output under control, we know that historically the earth has gone through very extreme natural climate changes.

If we want to keep the earth habitable by humans over long time-scale then we absolutely need to learn how to do minor terraforming. Much better to experiment on the moon or mars than the earth.

It's possible to care about more than one thing at once. Some people simply cannot be motivated to work on climate change, but there are 7.5 billion people on the planet, and they don't all need to work on the same thing. We just need a critical mass, the same as for any other problem.

Climate change isn't en existential risk, the way we deal with it is developing new knowledge which as a by product allow us to go to the moon or mars. Furthermore there is a whole other perspective on space which is military and includes china who is not going to hold back.