Rules for Destroying the Ozone Layer

[MerakSpielman]

Ok, I'm going to have a cataclysm on my world. I'm trying to think of what would work for this. The cateclysm is going to be a magically supercharged explosion centered on a single location. The observable effect will be to blast the landscape for about a thousand miles around. The secondary effect, taking place over the course of a couple months, will be to render the entire surface of the world uninhabitable, but the underdark habatable.

What sort of global change would have this effect? I thought the destruction of the ozone layer might do it (all the radiation getting through kills anything on the surface) but I don't know what that would do for civilizations underground. They need to remain more or less intact. I need the problem to be complex enough that magical-oriented folk (like on a D&D world) would not be able to figure it out without a few centuries of research.


Would this work? If not, what would? What would the rules be in D&D terms for walking aboveground with no ozone layer?

 

[Crothian]

How about just having all the dirt and stuff in the atmosphere form the basicas of a nuclear winter. Have another ice age happen as no heat can come in.

 

[Spatzimaus]

Nuclear Winter. Like Crothian said, the explosion/impact/whatever would throw a lot of debris up into the atmosphere; no sunlight, no plant life, things die. Sure, you have Daylight and Create Food and Water spells to keep food growing for towns, but the wildlife would all die out, and then the glaciers come.

The problem being, an explosion big enough to do that would probably rupture the crust, which'd be bad for the Underdark, so they'd go through some hard times too, but the part of the Underdark not nearby would probably survive (with a lot of cave-ins from the tectonics). Also, the drop in above-ground temperature probably would cool off the Underdark a bit too, but the killer above ground is the lack of sunlight for plants.

 

[1337 h4xor]

the above suggestion for nuclear winter sounds completely plausable with an explosion of that magnitude...

the debris and ash from the explosion fill the sky blacking out the sun, within a matter of months all plant life will die, and thus a chain reaction going up the food chain. underdark plant life that does not require light will not be affeced. and the frigid aboveground world would no longer be habitable people would have to move under the earth for warmth from the core of the world.

for your ozone depletion theorey pick a harmful gas and have that me a byproduct of this magincal explosion. For example if the blast released massive amounts of methane it would trap heat inside our atmosphere causing a greenhouse effect... the surface could become too hot to be livable and the oceans can rise with the remaining population sealing themselves underground being the only option...

get the elh and whip out some of those devistation vermin on the earth. The pc's can return when they're epic to get rid of them until then the population is forced underground where the vermin cant fit.



my personal favorite would be giant slugs with lasers on their heads have come to take retribution for all their smaller brothers and sisters killed my whirwind atacking munchkins. Thus the remain population is forced underground where the slugs cant fit.

 

[Al]

Then there's the old 'meteor impact' staple.

Think the dinosaurs (perhaps). Or any myriad of cheesy Hollywood films .

It would produce a similar effect to nuclear winter (in theory) not to mention being a big pain to any near the impact site.

 

[DanMcS]

How scientifically accurate is your world? For example, I don't see that a big explosion would necessarily destroy ozone- it's pretty high up. The nuclear winter thing could be possible.

Is everything made up of atoms of Earth, Air, Fire, and Water? Maybe the explosion supercharges everything on the surface with Positive energy, converting some of them to atoms of Mineral, Lightning, Radience, and Steam. (You can do pretty much the same with Negative Energy). The only escape is to the underground, where the shining energy of the permanent portal to the Positive doesn't reach. In this scenario, it might be possible to explore the surface at 'night', that is, when the portal was on the other side of the world, but you'd better be back underground before it dawns and your skin starts to boil.

Maybe the explosion cracks open a nest of tarrasques. They go on an eating spree, a la the dragons from Reign of Fire. Most underground tunnels are too small for them, I believe.

Perhaps the moon is knocked closer. The resulting tides and tsunamis wash over the land periodically, and it ends up being safer hiding underground in sealed caverns.

 

[AuraSeer]

If you just want an environment hostile to life, the thing that immediately springs to mind is the Negative Energy trait from Manual Of The Planes.

In order to allow people time to flee the surface, you'd fade the effect in slowly. First, plants and animals would start dying off, leaving people without food. Then, the hit point damage would start-- say, everyone on the surface loses one hp per week. After a month or two of that, up it to twice a week. Then once a day. Shorten the interval between each step, so that the death and destruction feel like they're accelerating.

Once the whole planet is affected, the effect tops out at 5 hp of negative energy damage per round, to every living creature on the surface. If you want, you could have the post-cataclysm world populated by huge numbers of undead-- they love negative energy, because it works as healing on them-- but it could just as easily be completely empty.

 

[Xeriar]

Would this work? If not, what would? What would the rules be in D&D terms for walking aboveground with no ozone layer?

Once a cosmic ray strikes a dioxide ('oxygen') molecule, it breaks it up and the oxygen atoms bond with other dioxide molecules to make... more ozone. So, the effect of destroying the ozone layer is...

More of an ozone layer.

Pretty much you have a nuclear winter scenario going on, lasting around a decade, probably, but if the blast radius is only a thousand miles, it's not so much a global catastrophe as a global annoyance.

The blast that killed off the dinosaurs wiped out over 90% of all life in North America in six minutes (according to calculations in an article in Discover magazine, anyway).

And even then the surface in certain parts of the world was habitable for small creatures. The oceans always stay pretty warm. The Earth hasn't been a snowball for a very, very long time.

 

[Zaruthustran]

Perhaps the moon is knocked closer. The resulting tides and tsunamis wash over the land periodically, and it ends up being safer hiding underground in sealed caverns.

Wow. Thundar the Barbarian, here we come.

How about removing all surface water? Go old-school, as in Old Testament, and either boil all the water on the surface or turn it into blood. That'd be cool. All water, when exposed to sunlight, turns to blood. Thus the people go underground, seeking subterranean lakes and springs.

Whether you use that idea or not, I'd go with a fantasy solution, not a scientific solution. The ozone layer is boring.

-z

 

[Kyramus]

hmmm let's see. Try to make the surface uninhabitable for a couple of decades or so......

Nuclear winter is nice, but the way to get that working could take quite a few things.

As I see it, there are two ways to do a surface inhavitable planet.
1) first we need heat, then cold. Have a group on one side of the planet toying with time magic. have another group toying with the effects of fire on a mass scale. Have another group play with cold magic. The group with time magic messed up and linked fire to the weave, scorching the land and evaporating the water. The people flee to the underground because of the heat. The time experimenters manage to finish their spell and nothing seems to happen. After 2 years, the heat spell disappears and replaced with a cold snap, one from the group of cold magic. The time experimenters didn't know this and thought it would happen at once, time is fickle and gave it two years. The surface is cold and few survive living up there.
It takes years before the cold snap ends. (great setting for a slow civilization growth into the surface again, look for ICE AGE story lines from Magic or some such.)
The characters will have to explore and set up areas that can be habitable. Epic level characters would be able to create permanent light/heat sources and such.

2) Something causes the sun to disappear, in a matter of days the land becomes cold and people dying. the only heat source is under ground. Years of research has availed little to the researchers. The deities are cryptic and seem to avoid the topic altogether or point out more pressing business.
The cause of the sun disappearing is because a wager was made between the gods of light and the gods of the dark. The dark believes that without the sun, the people will turn to the dark and become their people. The gods of the light believe that the people will remain faithful. During the deliberation, a trickster god tricked the gods of light to agree to the wager and the trickster took the sun out of the sky. He uses it as a lamp in his home.

It'll take Epic levels before the pc's can find a way to the trickster.

I hope the ideas help.