Every decline and collapse has a unique character of its own, peculiar to the body doing the falling. As limited as the understanding of the Bronze Age collapse is for example, there is a general consensus that that collapse was particularly catastrophic with many societies collapsing at once or in quick succession, with whole cities destroyed all over the Mediterranean region and beyond, which can be compared to the Roman Empire splitting in half, with the western half disintegrating more completely and the eastern half clumping up into the Byzantine Empire, which would stand for another thousand years. Catastrophic in its own way, especially depending on whom you talked to. But a different kind of catastrophe that does indeed have consequences for all involved.
What bothers me about the modern question is the incredible dynamic powers of social reproduction our societies posses. Strange way to begin a thought, certainly, but there's a point here. Because the secret behind that dynamism, that plethora of incredible material bounties and technical solutions which keeps a massive population growing, is enormous amounts of perpetual material growth.
You have at the same time these incredible powers of food production, transportation, communication, research, medical administration, and more, which are constantly working to reconstitute very rapidly societies that are constantly coming apart at the seams, often due to that very explosive dynamism and growth, and then meanwhile, you have a growing and universal unyielding pressure being introduced onto those robust systems of reproduction by resource constraints, pollution, and climate change, all direct consequences of that perpetual growth.
What we see on the ground now is what paradoxically looks like an excruciating stasis: all of this constant change and dynamism and yet nothing seems to change. Now it could be that we simply muscle our way into a long and gradual - albeit bumpy - decline through sheer brute force.
But there is also the matter of Seneca's Cliff, lurking in this case within the immense division of labor, where the industrial world derives its great power. The current precarity of the state of extreme specialization is such that huge sections of the population are shunted into ever more narrow sets of technical professional roles, or else inserted lower into the value chain with menial, repetitive tasks. Over the generations, this gradually destroys those capabilities of self-sufficiency that are built up over hundreds or even thousands of years. What is to be done if something goes very wrong? You now have very large populations dependent on smaller minorities for food production, processing, transport, all the rest.
The physical built environment mirrors this situation, with oceans of concrete and highways and parking lots, which are all tooled for the constant circulation of petroleum energy and manufactured products. With sustained disruption of this circulation, these regions could become resource deserts over longer time scales, and then even under shorter time scales, they imply sharp contractions as populations struggle for restricted resource flows.
There is an image I have in my head, and it has to do with the hydraulic splitter I operate at times to split larger volumes or tougher pieces of firewood. Its basically a big hydraulic arm that pushes down a wedge and can deliver some 22 tons of downward pressure. The controls are pretty dead simple and most of the time the machine is pretty safe. The danger comes when a piece doesn't want to split. The hydraulic arm starts oscillating and shuddering as it is bearing down, and then you've got to start watching that log: all of the energy is getting stored up in that wood, and as soon as it finally cracks, those pieces tend to go flying wherever there is room to go.
The image doesn't say much about the future: things can break apart in all sorts of ways. But then, where is all of that incoming energy going to go when that mass reaches its limits of growth? Standing armies with nukes is one way that sort of thing manifests. There are plenty of others.
