Post/Author/DateTime	Post
Aneutralshadeofblack 05-30-07, 12:20 PM	Yes, you're probably wondering what this is doing in the D&D campaign workshop. Don't worry, it makes sense. I'm going to be running a campaign that takes place on an Earth-like planet about three or so thousand years after global nuclear warfare wiped out most of civilisation and some other stuff happened. Basically, I have two sets of questions; since I know there are quite a few people who know about climate around here, I'm taking the liberty to ask. ;) Firstly, assuming that prior to this catastrophe, that world had a tech level roughly equal to ours in the late 1980s, at which point there was global nuclear warfare and an ensuing nuclear winter: how long would said nuclear winter last; how long would radiation damage last; how drastic would the climate change be and; could this modify the planet's tilt, spin and orbit, by how much, and what would be the effects on climate, day/year-span and the like? Secondly, on my world, the main setting takes place both on a landmass roughly the size of Australia, which has climate (but not geography) similar to the North American East coast; and on one the size of China and India put together which has climate similar to western continental Europe with a large stretch of desert from roughly Mandras to the Himalayas. Where would these end up being on this planet, taking into account the new climate. There's one caveat - they need to be within 2-3 weeks' distance of each other by late medieval boat of a size large enough to carry some hundred men. This is, of course, if it's at all possible for those two landmasses to exist on the same planet within the given parameters. I realise these are very specific, but I haven't been able to find any info on the net, so I resolved to ask around here and see if we might not have someone capable of answering this. D:
Araes 05-30-07, 02:41 PM	Alright, several of your questions are going to rest on the particulars of the "global" nuclear warfare. There unfortunately haven't actually been accounts on the ultra-long effects of nuclear winter. TTAPS is the most like what you are looking for, and was done in a partnership with Carl Sagan. It is unfortunately one of the only major works that looks this far out. In general, they found that nuclear winter would "probably" only last for a quarter to half of a year, no matter when it was triggered. They found that the freezing wasn't quite severe enough to freeze the oceans and trigger an ice age. However, if that were to occur, then you could be talking about decades or more and it becomes very hard to predict. However, an interesting result they did find was that the threshold for global nuclear winter was actually quite low, with only about 100 Megatons of bombs needing to be used over major metropolitan targets. This question completely depends on what types of bombs are used. If traditional nuclear weapons are used, then radiation levels would return to livable levels within about a half year to year - although there would probably be other long term effects to deal with if anyone actually did live in those areas. If neutron bombs are used, then the radiation would actually be of a shorter term, and areas could be used nearly immediately. However, if salted bombs are used, then it becomes an entirely different story. With proper dispersion, salted bombs could effectively last for decades in their effect. Cobalt bombs are the most well known variety of this, as they are designed as denial of area weapons that have the potential for mass extermination. Deployed into the atmosphere, the fallout could achieve world wide dispersion, and would still be strong enough to kill when it fell. Again, a reference to TTAPS, as its only extensive study on the subject. In general, they predicted negative 15 F for several months, with longer term reduction in temperatures by 3-4 degrees from normal. In general, no. Even though the force of the bombs is great, even exploded at a single point they're still not great enough to change the actual tilt of a 5.9742×10 kg planetary body. However, one interesting effect that people have recently noticed is that heating and cooling of the oceans actually slightly effects the spin rate of the planet, so if we chilled the ocean signficantly, then the spin rate of the world would actually slow down just slightly. Maybe a few minutes to an hour longer day. On your last question, I think that you would really be stretching things for plate techtonics, but you could basically put them at the latitudes of North America and the China India subcontinent, and then just squish them together so that they are within 2-3 weeks distance from one another. This would imply that your planet was signficantly after the armagaedon, but then again, if your players aren't climat- and geologists then you're probably not going to have too many issues.
GoriceXII 05-30-07, 02:58 PM	I would agree with much of what was said above so I'll put my two cents' worth in about the continents. The location in particular is something I agree with, it would be a lot easier to just say that they were fairly close to each other to begin with. I've played Twilight 2000 for a number of years and the writers of that game summed up a lot of the research by suspecting that something more like a nuclear autumn than a nuclear winter would take place. However the nuclear winter idea in part comes from the idea of tons of debris being flung into the atmosphere and remaining there for some time. So it is hard to say precisely given that there are different ideas on how the information available adds up. I overall I agree that it seems more likely that the difference would be of just a few degrees. That being said--if you think about it that's a lot. It doesn't need to be a plunge of 20 degrees for it to be significantly cooler.
Aneutralshadeofblack 05-30-07, 03:29 PM	Perfect - those are exactly the type of answers I was looking for. On your last question, I think that you would really be stretching things for plate techtonics, but you could basically put them at the latitudes of North America and the China India subcontinent, and then just squish them together so that they are within 2-3 weeks distance from one another. This would imply that your planet was signficantly after the armagaedon, but then again, if your players aren't climat- and geologists then you're probably not going to have too many issues. I said they were of a size approximately equal to the two bodies I mentioned, not that they were the very same ones. ;) In the setting, this catastrophe shattered most of the planet's landmass, causing large areas of land to disappear beneath the waves whilst others rose from the depths. The 1980s era tech I mentioned was more to give you an idea of what type of nuclear weapons would be used (probably neutron bombs, if I remember right and they're the most immediately destructive) rather than an actual guideline; given the amount of destruction provoked by the event, it seems likely it would have been continual orbital bombardment for quite some time. That being said--if you think about it that's a lot. It doesn't need to be a plunge of 20 degrees for it to be significantly cooler. I can imagine the effects would be important in the direct aftermath of those events, but what kind of damage would they have wrought that would last more than three thousand years? I guess that's kind of the same as asking "what would Earth look like three thousand years after there was a war so big it blew up most of the continents as we know them?"
OleOneEye 05-30-07, 11:50 PM	Modern nuclear weapons are not capable of shattering continents. A full nuclear exchange between the U.S. and Russia would not alter how the continents physically look. However, in a magical world anything can happen. There are websites that speculate on how techtonic plates are presumed to shift in the future (though we are talking millions and millions of years). It may be interesting for you to look some of them up to get ideas on what a future Earth may look like.
Werral 06-08-07, 08:25 PM	If the Nuclear Winter was deep enough then glaciers might form over the sea and so the landmasses would effectively be closer to each other. There was one speculation that a nuclear exchange could knock the Earth out of its orbit. If you went with that you could do what you wanted with the climate. If you want magic and stuff look out for the old Rifts game, out of print, but basically a nuclear exchange acts as a mass human sacrifice thus turning the Earth into a multidimensional nexus.
Anuvrix 06-10-07, 12:50 AM	The magic aspect of the DnD multiverse can have a very prolonged and powerful affect on the "nuclear war" one would experience. With the right alchemical knowledge, a cabal of wizards could, in theory, combine the right (possibly multi-planar) materials and create the ultimate material component, or material itself, to create an explosion that would cause a long lasting radioactive fallout. Massive rainstorms would be nearly constant. The warmth of the planet could be variable, the explosion could very well heat up the core of the planet, causing volcanic activity to increase twenty-fold. An explosion of thhis magnetude could shatter a mjority of the crust, especially near "ground zaro". Expect to find nothing but a crater the size of the gulf of Mexico at "ground zero". At the three-thousand-year mark, the temperature and climate would have significantly restored, massive storms would still be fairly regular, the "ground zero" could have turned into a solid landmass, and possible fully vegitated and populated by wild animals. The center would be a massive sea, circular in nature. Entirely new continents could have formed, while the old ones are still sinking beneath the new plates.(the newer plates would be more bouyant than the old ones, due to large amounts of volcanic gasses in the rock) the people would be abandoning cities, leaving for new colonies sprouting up on new continents. For the time period you're suggesting, the majority of the world would be highly fertile and the new Rainforests, that will cover most of the world, will filter out the atmosphere quickly. An elf born in the time of your campaign could very well live to see the world's climate restored. *will finish later*:D