> Environmental concerns are selfish.
That's overstating it.
Yes, life will go on. But it's not only us that will die - as you say, much of the marine ecosystem will die off, we're not the only animal that has problems with wet bulb temperature (most don't even sweat), and humanity isn't going to die of starvation before we make everything remotely edible out there extinct first.
Life is going to look extremely different, it's not just us.