I agree with you on most things..except for the conclusion that some people (not you, I think) seem to draw from this statement:
which is that
a= energy and resources spent or depleted rearing livestock
b= energy and resources spent or depleted growing crops we eat
c= energy and resources spent or depleted growing crops to replace said lifestock
and that that's all there is to it.
Farming doesn't just mean plant a seed, water it and wait until it grows.. When you do that, you deplete salts and other minerals that are in the soil and that need time to be replaced by new ones.. so..farming more intensively because you need more crops means you deplete those resources faster..and need to tear down more forest in order to extend the fields.. that too causes greenhouse effect..
It means modifying the lay of the land drastically..we've done it forever, ever since the egyptians started trying to regulate the floods of the Nile to favour their crops.. ever since we dug the first irrigation channel...
Hell...even the bible tells us about resting on the seventh day and about how that translates in years when farming is involved..if I remember my studies well, according to scriptures, we're supposed to let a piece of land rest every 7th year, so that it can rebuild it's nutrients for when we go back to planting stuff on it.
Whoever did put the bible together knew this even back then, at a time when farming was difficult and uncertain at best..and still very much not as intensive as it is today...
There are too many unfathomable variables that come into play for us to reduce it to a mere thermodynamic equation.
The whole idea that stopping to eat meat would solve certain issues, which is what some of the preachy vegetarians or vegans try to push down our throats is just so full of bull that someone should tell them
P.S. I'm not quoting the bible to spread any word or talk about theology.. far from it..definitely not the right guy for that..
I'm just saying, hell..they knew this about farming even back then, several thousand years ago (we're talking old testament, if memory serves me well).