There's a metaphorical elephant in the room that people aren't talking about.
Over-population.

The thing is, we can pretty much estimate what the carrying level of the Earth is, i.e how big a population can live in a sustainable fashion given current agrarian technology.

The problem is: that number is around 2 billion, plus or minus a billion or so. [although climate change is likely to degrade that.]

So far, not really seeing much to address this issue that doesn't depend upon other non-sustainable technology.