> To save the world we need: a substantial price on carbon,
No we don't. Global warming is a self-reinforcing effect. So there's no point to slowing down emissions. No point at all. Even if you get it to zero, the resulting concentrations will still accelerate into the right. Even if you get it negative at the same rate we're producing it today (which would eliminate all human co2 contributions EVER in ~60 years) would do nothing but delay.
So why bother ? This avenue is closed, and useless.
We glued a grenade to our hand, and pulled the pin. Messing around trying to insert the pin back in provides nothing but comic relief. We need to adapt. To limit the damage, and fix things.
As you say, only direct geoengineering can work. On the plus side: doesn't require global cooperation. On the downside: that'll make someone clearly directly responsible for the (MUCH worse) effects global cooling will have, especially locally ... so it's extremely incompatible with how current green parties think and "influence policy".
Whereas the current "complain and do nothing but token efforts" is very good at getting constant attention, votes and money. But only if the problem keeps getting worse.
So just like everyone they accuse, green and leftist parties themselves are dependent on global warming happening and getting worse. Maybe that, too, is a reason why we have nothing but token efforts. Also, they would have to admit that "mother nature"/gaia is definitely NOT going to save our ass, even if we stop polluting.
Additionally, Gaia, so to speak, has already decided to inflict global warming on us, as a punishment or just because, take your pick, effectively for what humanity did at the end of the 19th (not 20th) century. So we need to inflict further damage on the ecosystem artificially controlling the temperature to prevent worse. But that'll futher destroy habitats, and on a much larger scale than what we've seen so far.
Not eating meat, capturing co2, lab-grown meat, even nuclear power ... just can't work. Only geoengineering can work.