Designing an apocalypse to order

[Luke Bunyip]

For my next game's setting, I'm using sea level rise, limited nuclear exchange (as per above re: duds), and a bit of biological warfare (cough mutants cough). And the occasional AI as a sort of low competency Reign of Steel.

My aim is a pre Industrial to Early Industrial base technology, with a mix of Mad Max and Borg-like cyborgs. Things are improving, but slowly on my setting's Earth.

[Michael Thayne]

Originally Posted by Kale

If you plan on having your PCs actually visit Earth at some point (or your campaign starts on Earth), then consider using After The End to work out some of the finer details of the apocalypse. That book has an "Apocalypse designer guide" that will really help work out the nitty gritty of how things ended. If the PCs probably won't visit Earth, or will spend very little time on it, then you can have vague myth and rumors reach the PCs ears with little detail, so you won't need to work so hard on writing up the apocalypse. You can just hand wave it away as "Nuclear War between world powers devastated most urban areas. Hardly anyone even remembers how it started anymore."

I actually was thinking about doing something like this originally, but After the End seems to assume a longer "recovery time" than I am. Plus, I don't know how much history really gets lost forever when you have space colonies with working databases.

Originally Posted by Irish Wolf

"Slamming comets into the planet" would be more a K-T Event sort of thing, I would think, rather than the more, ah, genteel apocalypse you seem to have in mind.

Originally Posted by khorboth

We are admittedly well outside my expertise, but wouldn't that depend upon the mass and velocity of impacting objects? We do get impacts every so often with varying levels of damage, so something between "moderate crater" and "everyone dies" seems plausible. Indeed, documenteries love to measure the strength of meteor impacts in atomic bomb equivalents.

I was thinking along khorboth's lines. The K-T event has been estimated as involving 100 teratons of TNT equivalent. Tsar bomba was designed for 100 megatons (actual yield was less). Maybe I should go for the geometric mean of those two values, i.e. 100 gigatons? Some quick math suggests we're talking about a chunk of ice on the order of 4 billion tons, if it's coming from the outer solar system. I don't know what kind of effects that would have in practice.

Originally Posted by thrash

You might want to check the math on this one. In a setting where an Isp of 30,000s is "high," you'll either need a very lucky find (e.g., like C/2013 A1 and Mars) or years of prep. A fusion torch large enough to move a continental-scale disaster comet won't be stealthy. Even if one were able to hide the drive plume, the suspiciously trending non-gravitational forces on its orbit would flag it immediately as under control and invite retaliation.

So I was thinking a setup like this: China (or whoever) starts a Mars terraforming project, requiring huge amounts of ice to be imported from the outer solar system to Mars' surface. But secretly, they make plans to redirect the comets from Mars to Earth in event of war. A setup like that won't have any effect on the opening phase of the war, but it could serve as an ultimate "revenge weapon". Ideally, it's just a deterrent, but when deterrence fails, well...

Of course, once you realize a comet has been redirected you can try to stop it, Armageddon style (I'm talking about the Bruce Willis movie). But if your infrastructure has already been wrecked by the first phase of the nuclear war

Originally Posted by copeab

Zombie apocalypse, aka use of weaponized rabies that goes terribly wrong.

I've thought about this. Certainly could be one element. As the main event, I'm not sure you can really wreck civilization without getting human extinction, though. The thing about a nuclear war or even comet strike is that eventually the dust settles—literally, the sun might be dimmed for awhile by the smoke from everything burning, but eventually the sun can come back and people stop starving. IDK, the Black Death wasn't really a "civilization collapses" event, but maybe it slowed technological progress for a couple centuries? I don't think it did, but there might be more to the story than I'm aware of.

[Varyon]

I've designed two partial apocalypses, which might be potentially mineable here. Note these are on the cinematic side, but if the events from Armageddon would be OK in your setting, these should be fine.

First, the prelude to a zombie apocalypse (itself due to a nanite plague from another timeline, and unimportant here). That was near-future, and involved a first strike from North Korea, leading to retaliation from the United States and counter-retaliation from China, which pretty much got every nuclear power involved. The nukes actually did relatively little damage, thanks to most being shot down by orbital lasers designed for just this purpose (basically a rebirth of SDI), but were enough to cause some serious destabilization. Said destabilization was largely of governments, but one particular missile, an errant "bunker buster" aimed at some military base or another (I forget which, or maybe I made one up that was deep enough to need a bunker buster nuke), detonated in the Yellowstone Caldera, triggering a super-eruption that caused wide-spread destruction and significantly disrupted the global climate. All this wasn't enough for a proper apocalypse, however, but destabilized things enough that Reich-5 was able to set up a clandestine lab to study a plague they found in another timeline, and when that escaped their somewhat-lax containment, a proper (zombie) apocalypse began.

In my Harpyias setting, which takes place entirely on interstellar colonies, shortly after Earth's colony fleet left the sun experienced a huge coronal mass ejection, which wiped out all orbital assets and blanketed Earth in electromagnetic storms, knocking out pretty much all insufficiently-hardened electronics. I'm purposefully vague on exactly what happened next, because it doesn't actually matter for the setting, but suffice to say there was widespread chaos. An extreme radical group managed to seize power during this time, which does matter for the setting - while the characters will never encounter anyone who has set foot on Earth, and will never do so themselves (it takes 100 years with the newest technology to get from Earth to the colony closest to it, and longer to get from said colony to Earth), one of the antagonistic polities of the setting is officially a branch of Earth's government.

[Michael Thayne]

Originally Posted by Varyon

I've designed two partial apocalypses, which might be potentially mineable here. Note these are on the cinematic side, but if the events from Armageddon would be OK in your setting, these should be fine.

Note that I was using Armageddon as lazy shorthand for the government / military Does Something about the killer comet they had considerable advance warning on. Even if the events of Armageddon are unrealistic, with advanced space drives there's a lot you could try to do to divert an oncoming comet, and I thought it was worth coming up with reasons why they might fail.

[Varyon]

Originally Posted by Michael Thayne

Note that I was using Armageddon as lazy shorthand for the government / military Does Something about the killer comet they had considerable advance warning on. Even if the events of Armageddon are unrealistic, with advanced space drives there's a lot you could try to do to divert an oncoming comet, and I thought it was worth coming up with reasons why they might fail.

Fair enough. I recall reading a bit of flash fiction over at 365 Tomorrows that involved a comet on a collision course with Earth, with people landing on it and basically strapping a mass-driver to it, cutting out blocks of the comet and using the drive to fling them away (diverting the comet in the process). It ended up hitting the atmosphere, breaking apart, and mostly missing Earth itself... but the story ends with one large chunk heading toward the moon while the colonists there look on in terror.

For your purposes, something similar could happen, with the best that can be done still involving an impact with our atmosphere (and trying to angle it to "skip" off, which IIRC was the goal in the story), which could then break off sizable enough chunks to cause widespread damage.

[Fred Brackin]

Originally Posted by Varyon

Fair enough. I recall reading a bit of flash fiction over at 365 Tomorrows that involved a comet on a collision course with Earth, with people landing on it and basically strapping a mass-driver to it, .

For this scheme you need a relatively solid asteroid of stony or metallic composition. Not a comet. Comets seem to be made of frozen gasses.

You could set up a nuclear thermal rocket and just pump the gasses into it but there's probably nothing solid enough to mount it on.

I'm afraid that it really would make more sense to nuke a comet even if you think nuclear explosions are vulgar. Vaporizing the gasses and scattering them on the solar wind would seem to be a fine idea. You wouldn't even need to land. you'd use a warhead from range and if the first one didn't affect the core of the comet you use another one.

So, _Asteroid!_ and no rubble piles either.

[Kale]

Originally Posted by Michael Thayne

I actually was thinking about doing something like this originally, but After the End seems to assume a longer "recovery time" than I am. Plus, I don't know how much history really gets lost forever when you have space colonies with working databases.

ATE Vol 2 Page 8 actually discusses the time frame. Their shortest example is 2-3 generations if that works for you. There's also a box on the same page with an "Even Shorter" paragraph that might help.

[Michael Thayne]

Originally Posted by Kale

ATE Vol 2 Page 8 actually discusses the time frame. Their shortest example is 2-3 generations if that works for you. There's also a box on the same page with an "Even Shorter" paragraph that might help.

I'm aware of all that. Where I'm seeing discrepancies between AtE and what I'm planning is I'm planning to have Earth largely recovered after 200 years, which probably translates to six or seven generations. AtE suggests requiring Anthropology rolls for all but the most basic facts about the old world after four to six generations, and for all facts about the old world after seven to ten generations. On the other hand, I'm assuming that if nothing else contact with space colonies prevents that level of knowledge loss. AtE furthermore assumes that the genre shifts to futuristic sci-fi after more than ten generations, and I specifically want a shorter timeline so the space colonies don't have too long to grow--I want Earth to be able to bounce back as a hegemonic power by the setting's "present day".

Unrelated, the thing I keep coming back to in this is wanting to read informed speculation on the effects of different sizes of asteroid/comet strikes. There's six orders of (decimal) magnitude separating the energy of Tsar Bomba and that of the Chicxulub impactor. That's actually a pretty good range of possibilities! I particularly want to understand how the effects of different sizes of impactor are likely to vary by part of the globe. If the effects were truly uniform I could just pick an effect level and avoid specifying the mass of the comet.

[Fred Brackin]

Originally Posted by Michael Thayne

I

Unrelated, the thing I keep coming back to in this is wanting to read informed speculation on the effects of different sizes of asteroid/comet strikes. There's six orders of (decimal) magnitude separating the energy of Tsar Bomba and that of the Chicxulub impactor.

Knock the bottom orders of magnitude off your scale. They have no chance of even making world-wide civilization hiccup.

The actual Tsar Bomba appears to have been 50 megatons. It's outer layer would have to have been uranium to hit 100 and instead it was lead. The effect of a single exploosion of this magnitude on world civilization is barely detectable.

Let's skip a level and go to the big volcanic explosion of 1815. That was rated at 10,000 megatons and it produced highly colored sunsets and a "Year Without a Summer". That was a noticable effect but not a catastrophe.

So that's 3 of your levels gone but that volcanic explosion was the biggest I know of in historical times. You need something bigger and/or a lot more of them.

I don't really think asteroidal impact is a good choice for what you want.

[Michael Thayne]

Originally Posted by Fred Brackin

Knock the bottom orders of magnitude off your scale. They have no chance of even making world-wide civilization hiccup.

The actual Tsar Bomba appears to have been 50 megatons. It's outer layer would have to have been uranium to hit 100 and instead it was lead. The effect of a single exploosion of this magnitude on world civilization is barely detectable.

Let's skip a level and go to the big volcanic explosion of 1815. That was rated at 10,000 megatons and it produced highly colored sunsets and a "Year Without a Summer". That was a noticable effect but not a catastrophe.

So that's 3 of your levels gone but that volcanic explosion was the biggest I know of in historical times. You need something bigger and/or a lot more of them.

I don't really think asteroidal impact is a good choice for what you want.

Hmmm. I wonder how big of a comet you'd need to basically render both New York and DC only dubiously worth resettling at the same time? Probably bigger than the Chicxulub impactor if we're talking about a crater from a land impact, but a water impact in the Atlantic could create huge tidal waves. But I don't know, like, how big of a tidal wave it would take to level every skyscraper in New York City.