Any kind of apocalypse that could plausibly happen is good. As long as if it were to happen, it wouldn't realistically wipe out the population completely, would temporarily destroy all civilization (as in countries governments no population), and would leave the environment scarred and a bit inhospitable, but not so much that it wouldn't be able to come back from it within a century.
closed as too broad by sphennings, Azuaron, CaM, Separatrix, L.Dutch♦ Aug 18 '17 at 17:13
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At this point, the most likely thing that could cause the collapse of global human civilization would be drastic climate change. If the earth's temperature raised to an unlivable level, the cities we currently have would become completely unlivable as well because they are, for the most part, exposed to the elements, and many are within range of coastlines that could swallow the cities themselves. Billions would die as all our crop plants wither in the heat.
But, small groups of humans could survive in underground, climate-controlled bunkers, a la the Fallout series. The largest dangers of post-nuclear wastelands are shared by climate change raising the temperature drastically: Namely, food and potable water shortages and radiation exposure (albeit the types of radiation are different, nuclear vs. heat/UV radiation). So, many of the tactics employed by the vault dwellers in that series (EG labs where plants are grown from cell cultures to ensure maximum food output in the bunkers and strictly controlled populations to ensure the number of people does not exceed food production capacity) could also work for your survivors.
Of course, depending on the technology level of your civilization pre-warming, they may be faced with some different problems, such as how to generate electricity for their bunkers (in Fallout powerful nuclear reactors are used which take fuel that lasts hundreds of years; your civilization may not have this technology level), but there should not be anything insurmountable for a small group of highly intelligent people. I imagine solar panels would become very valuable in this world.
It would be up to you if your bunkers also involved deranged experiments on the residents the way the vaults in Fallout did.
Wow, okay there are many ways society can collapse without killing off humanity as as a whole.
Does history give us any examples?
Why yes, it does. Let us review a few of those...
Fall of the Roman Empire. From the link:
The Fall of the Western Roman Empire (also called Fall of the Roman Empire or Fall of Rome) was the process of decline in the Western Roman Empire in which it failed to enforce its rule, and its vast territory was divided into several successor polities. The Roman Empire lost the strengths that had allowed it to exercise effective control; modern historians mention factors including the effectiveness and numbers of the army, the health and numbers of the Roman population, the strength of the economy, the competence of the Emperor, the religious changes of the period, and the efficiency of the civil administration. Increasing pressure from barbarians outside Roman culture also contributed greatly to the collapse. The reasons for the collapse are major subjects of the historiography of the ancient world and they inform much modern discourse on state failure.
Fall of the Maya Empire. From the article, we see several vectors mentioned, though no consensus is reached. These include foreign invasion, collapse of trade routes, epidemic diseases, and drought / ecological collapse / climate change.
Fall of the Chinese Qing Dynasty: Basically seems to boil down to civil unrest resulting in assassination.
Fall of Egypt's New Kingdom. Egypt was taken by Assyrian conquest.
Fall of the Aztecs. The Aztecs were conquered by the Spanish.
The Hittite Empire. was largely destroyed by drought.
I could go on listing other empires throughout history, but this proves the point that empires do collapse, taking their civilization with them.
So what factors can we condense from this?
There are a list of factors that can decimate a civilization but leave survivors in some capacity. These include:
- climate change (especially drought)
- inept/corrupt rulers
- conquest by other rulers
- natural disasters (for small city-state scale civilizations primarily)
And then there are some situations that we as a species have not yet suffered through, but that could cause modern civilizations to collapse as well:
- nuclear war
- biological/germ war
- alien invasion
- meteor/asteroid impact
- climate change/ice age/etc
- massive solar flares
- gamma ray burst from some nearby neutron star
Given that our civilizations span so much more territory than ancient civilizations often did, and the fact that global trade insulates us in some respects, we have some natural defenses from localized disasters. Civilization is much more intertwined now than ever before. So things like volcanic eruptions, tsunamis, or earthquakes are not really able to destroy entire civilizations anymore. They are disruptive and deadly, yes. But not to humanity as a whole or even a civilization as a whole.
But modern civilization is heavily dependent on technology. Take away our electrical grids (via massive solar flares for example), and civilization might collapse as chaos consumes the cities and spreads outward.
One of the simplest ways is to let Homo Sapiens continue his current job and hope to have something better than cockroaches among survivors.
... but this may not be what You're looking for ;)
It really depends on what You need for your plot.
If you need "natural events" then asteroid hit, huge supervolcano eruption or a global pandemic are good candidates.
If you want something willingly done You can think about a gang of super-terrorists targeting all oil production sites at once (or some other way to have oil production stop). Strategic reserves will last few months and in the meantime global transports would come to a grinding halt with a terrifying domino-effect (almost no country in the world is self-sufficient to feed its own population, even countries that are (e.g.: U.S.) would be hard pressed to maintain the same production levels without oil).
Rogue A.I. is not really out of the way.
For generic "good reasons" for Civilization to fall see also Wikipedia