Gee! Speaking of, "intellectual gymnastics", you just showed us how it's done: Telling us the warming climate improved crop yields that fed bigger cities which grew faster than their sanitation, but standing that on it's head to say it had nothing to do with climate. Then flipping to how the later cooling climate caused crop failures, but somersaulting over 'no food' to, 'no famine'. Those were caused by invading armies, taking from others what they didn't have at home. Food.
All sounds pretty climate-driven to me, but the gymnastics were impressive.
Oh yes, I also note that in the growth of the cities, and in the supplying of the armies there was a whole lot of money being made — by some at least — adjusting to, and accommodating those realities of climate change.
Stupid to resist what's happening all around because you don't like what your thermometer reads.