P.S.:

To answer your question at the end more directly: No, I don't think subsistence farming is a "realistic solution for carbon and climate." I am friends with some small holders. Meat farm and veg. The numbers are challenging; small farms likely can't reasonably feed the world at current population levels. But I don't expect that to work, any more than I expect a one-for-one swap to renewables. I think it's going to be everything in the bag of tricks. We should all be doing everything we can to reduce our dependency on (and addiction to) the global supply chain and industrial consumer machine. We should also be looking at every possible large scale solution, switching to lower carbon alternatives, decarbonizing, electrifying, etc.