Hmm. Under communism, even with UBI, people would still have jobs, or hobbies, or would go on road trips or vacations, so you'd still have people driving cars.

I agree that better, more walkable city planning and functional public transit is important for reversing climate change, but lots of people think that, not just communists. I don't see what a communist revolution has to do with that - even your example is of Soviet cities, not communist cities.

And even if there are not energy companies under communism, there still need to be power plants, electricity would still need to be generated. What about communism would make those power plants be powered by renewables instead of coal?