and there's one thing those ancient people, from all corners of the globe, knew that we modern first-world people don't know. They knew, in a very immeidate and hard-edged way, the reality of the danger of starvation. There are places in the world were the people still know that, but here, in our insulated world, cushioned as we are from the effects of nature, we have no idea whatsoever just how close to starvation people always are, and always have been, and always will be. We don't notice it as much in today's world, but everything we do revolves around finding and securing our next meal.
Large empires had built-in safeguards against short-term drought and local disasters. The Roman empire drew its food from all over Europe and Africa, so a couple years of drought in one place was hardly noticed. But when the growing zones shifted and the weather turned drier for a few decades, the Roman way of farming ceased to work, and even the mighty empire knew hunger.
With climate change we will see growing conditions change all over the globe, and people who never gave a thought to where the next meal would come from will start to hear their stomach rumbling. And what will happen then is what has always happened throughout recorded history and even long before. Hungry people will do what they need to do for food. They cross borders, in spite of armies trying to hold them back. They topple governments. They raid storage facilities. They kill their neighbors for their grain and livestock. They band together under strong local warlords and gang leaders to fight nearby warlords and gang leaders over whatever food and water is available. And after many decades of social and political chaos, they die in huge numbers. And the remaining few disperse into the surrounding countryside to set themselves up as subsistence farmers again until the weather shifts once more and they can start a whole new round of empire building.
What we are experiencing, and what we will experience in the immediate future is nothing unusual. It's chaos of the most ordinary kind. The only differences being that we have farther to fall from our lofty technological peak, and it is affecting the whole planet at the same time. (Although that will not matter much as the world becomes intensely local, and increasingly structured around the tribe/gang.)
I know a lot of people have idle dreams of some "sustainable utopia" after the fall, but history exposes that fantasy for what it is. After the fall is about violent tribal warlords. It always has been, no matter where or when in the world you look, and it always will be.
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