People forget that horses are horribly inefficient at converting food into pulling power and breathe out CO2 all day and crap everywhere. Old cities were full of horse**** (and smell etc) and tbe combustion engine was seen as a Godsend in cleanliness when introduced.
As you say, we are in a closed system and a limited set of resources. Either some people reduce their consumption of just about everything (standard of living) or we have less people. The various religions haven't grasped this and have been a source of the problem for a long while but everyone is too PC to challenge them properly.
