Hey guys, I hate having to look for help when it comes to plotting, but I'm at a loss here. I have an idea for a novel where mankind has built a massive underground network of tunnels and cities after being forced to leave the surface. I can work with stretching the rules there a little bit. What I need, however, is a reason for them to move down and stay down for a long period of time (several generations) before the time of my novel, when the time has come for them to move back up. Nuclear fallout is out of the question, since no fallout would last 100+ years. And I want something that mankind can eventually recover from, to return to the surface — whether that requires ecological reconstruction or re-terraforming remains to be seen. As overdone as it is, could an impact event (meteor/comet) allow for such a situation? Could an impact event make most of the earth's surface uninhabitable but leave the underground protected? Thanks in advance for any advice.
A sharp increase in solar radiation due to collision of an extrasolar piece of matter with the sun? Increased surface temperature and solar radiation for several decades makes the surface uninhabitable. The surface vegetation and animal life would be all but wiped out, but deep undergraound could be livable for a small part of the population. When conditions return to normal, the surfave could be replanted from the life forms preseved in the caverns. Also, undersea life could survive, although many species would die out. The ocean would be an important food source during the underground years. Algae could provide oxygen replenishment for the reduced biological population.
Cause - an unusual period of massive sun flares, leaving the surface uninhabitable until the events subside naturally. This could last as long as you want...months, years, decades. People could survive on such foods as mushrooms and subsurface meat sources like worms, bugs, cave-dwelling fish. There are several species of blind Amazon catfish that survive without light and Mississippi catfish exist in severely turbid water, essentially without light. There's no reason fish farming couldn't happen underground. Also, the surface might be uninhabitable and surface water unavailable but subsurface aquifers should be relatively unaffected...spontaneous cave flooding might also be a good complication bringing tension to your story as characters escape drowning, etc.
An epidemic of some sort? If you wanted to diminish humanity's numbers, that could be a good way to go about it. As for why they stay underground for generations... fear? Maybe those who have put themselves in charge have laced the minds of the naive; after all if you're born with a notion taught to you it would take some feat to reverse it.
Just a thought but... over what timescale has mankind has built an underground network of tunnels and cities? Even to start building tunnels (with cities to follow in the decades later) would take some time. Therefore your catastrophe would need to give mankind some warning to prepare for it. I'd personally go with global warming - but volcanic activated and not man-made. It has it's basis in science and happened over a number of decades. Although there would be issues about oxygen and I struggle to see how man would venture out in even a hundred generations. Hmm, this is hard.
This is one of my biggest hurdles. This underground network is not primitive. The background of my story (as it stands) is that something catastrophic was predicted, and an emergency underground shelter was built to preserve a small fraction of the population. The tunnels would have began as primitive bunkers, but over time — decades — they become bigger and more advanced as the survivors realize that these tunnels could be their home forever. By the time of the novel, I'm thinking these tunnels would be miles wide and deep, with advanced man-made ecosystems as a product of generations of research, advanced computers and a population in the tens of thousands. I'm just trying to wrangle with the limitations of believability. Mining deposits could provide resources for architecture and manufacturing, but how do you get prolonged access to water for a relatively large population (or, in reference to Cogito's suggestion, how to you access ocean fish and water from underground)? How would you provide electricity? What about communications? All of these I could easily answer in any other situation. Underground, however? Not sure I can. Hard science isn't my strong suit.
Here's a thought: don't explain it. Assuming the characters in the actual narrative timeline of the story are several generations removed from the event, they've never known the surface world and might not understand the exact nature of the event anyway. Figure it as a sort of myth, an almost religious event that suggests a possible historical reality, but doesn't pinpoint it. Human experience is so intertwined with the experience of imperfect memory and the process of myth-making that it could create a really interesting layer to your idea.
I think the time is definitely ripe for a post-Armageddon type blockbuster novel, although I guess H.G. Wells has already shown us what the future will be like in 'The Time Machine'. But you could have the optimist's version--what remains of mankind has been cooped up underground so long, sophisticated ways of harmoniously getting along have been developed, and to pass the time, they wrote poetry and had philosophical debates... Oh, I just remembered a visit I was taken on as a child, to Chislehurst Caves, near Bromley in England. I suggest you look it up. There were miles of dark, mysterious passageways dug out by hand, dating back to the times of the Druids. Plenty of research material there on how people lived as cave dwellers.
Here are some suggestions: 1. Gama Ray Burst - burns off the Ozone layer of the planet and UV radiation would blind and kill every living organism on the planet not 4 feed underground. It stops cellular activity. It would take hundreds if not thousands of years for simple life to begin anew. 2. Global Warming led to the thawing of the permafrost around the global releasing massive amounts of methane gas from the billions of tons of now rotten plant material in the permafrost. Poisoning the air for organisms that need nitrogen and Oxygen 3. Genetically engineered crop (say wheat) was altered to become extremely resistant to pests and chemicals in an effort to strengthen the world’s bread basket production. Let’s say it was cross-bred with the genes of a tropical frog who is resistant to funguses. It cross-bred with a common weed and the weed choked out most of the other plant life in those regions. People went underground to escape the warring over food. (meh) 4. Use the Bikini Islands as a starting point during the testing of nuclear bombs. The first detonation killed off the first link in the food chain in the sea and it took decades before it was realized. Once sea life began dying off link by link and the ocean being overfished and polluted, humans only had land sources for food and they, too, went forcing people underground. 5. Scientist discovered a cloud in space that was – oh lets say 1.4 light years in length – and it would pass through the inner plants. The chemical composition was determined to be mainly hydrogen which when it hits our atmosphere would begin binding with the O2 and making lots and lots of rain and water. This would lower the O2 levels in the air and force people under ground. 6. Yellowstone Super Volcano erupts. That is an extinction level event. Planet life would die off with no sun light and dropping temps. 7. Nanotechnology developed nanites for attacking cancer cells. The military weaponizes this technology for assassination attempts but failed to fully remove the self replicating function from the medical design. All humans would be targets for death and never see it coming. 8. Bob the Spiritual Tomato in the Garden of Love leads his wicker basket army against the evil pizza delivery unions of outer Mongolia leaving a wake of deadly radiation Then again, presenting the situation as absolute really worked well with "The Road"
Errr... Maybe I'm wrong here, but it seems like you are virutally trying to write a story set in a similar (if not the same) universe as is in Metro 2033, by Dmitry Glukhovsky. Is this your inspiration for this universe, maybe? Also, there are many scarily close descriptions that bear many similarities between `your` universe and the one of Twelve Monkeys, directed by Terry Gilliam. That said, interesting idea and all but it's not original enough to be worth a read (at least to me) unless you can modify the idea enough away from these two set universes. I mean there is even a computer game based on the book of the same name and it doesn't try to hide/lie/make it out to be anything it's not. It just seems you're doing the same thing here. Pardon me, if I'm wrong, of course. You could go for the ideas of mankind creating tunnels but not to any massive degree and each of them being seperate from each other. Then, as people go above ground, they build settlements above ground to supply them with food and water and then slowly dig further into the Earth to see if there are any other tunnel complexes around. Stuff like that. Some of the people up top have some cool ideas that I think would work well. Anyway, I might be being overly-critical and negative here, but it had to be said. Besides, I'm an `extreme cynic`, so it's a given that you'll get responses like this from me.
I'm partial to zombie virus scenarios, interdimensional portals opening and bringing with it humans or other creatures who want to take over the world, natural disasters (be it volcanic, asteroid, or other such things) and aliens.
I can’t offer too much help here as I have a similar story myself, but the suggestions all given are very good reasons for staying under for so long, but as one poster has already said, why explain it at all, maybe it is so far down the line that people have forgot the original reason, or maybe they are so scared that they haven’t realised the reason is no longer valid