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Message: <blockquote data-quote="Zardnaar" data-source="post: 7555150" data-attributes="member: 6716779">Some of the other threads (generation ships etc) have made me start this thread. Extinction level events have been a part of mainstream pop culture since at least the 80's and have been a sci fi trope before that. For some of them there has been a fair amount of panic (nuclear war, climate change) but for the most part I do not count them as ELE. This is because unlike most animals humans can adapt and I think it would be fairly hard to wipe humans out at least to extinction levels. Not claiming a few things would not really suck and kill billions but there would be survivors.  Nuclear War Post apocalyptic nuclear war stories are a dime a dozen and were fairly common during the cold war. Nevertheless I have severe doubts as to such a war actually wiping us out as a species. Being near a blast would really suck but since 1945 there have been around 2000 nuclear detonations. However a nuclear war miht have that many warheads or more going off all in a short time frame. A limited nuclear war would not wipe us out although the dust etc thrown up into the atmosphere might cool the planet temporarily similar to a large volcano going off. The worlds nuclear arsenal is apparently a bit less than 10 000 and in a full scale nuclear war I have doubts as to how many would actually be launched due to a break down in communications and military high commands getting vaporised. The real threat is a hypothetical nuclear winter where the amount of dust thrown up into the atmosphere. Even then some humans would likely survive either somewhere in the world or the dust might clear quicker than previously thought possible. How many nukes it would take to cause this and how long lasting the effects would be is unknown although even a short term disruption to world wide crops would kill billions. But there would be survivors. A nuclear winter lasting more than a few months or a year or two would likely be an extinction level event but you do have survivalists and under ground bunkers in places like North Korea so it would depend on things like food stockpiles and how long it would take for the dust to settle to let in enough light to grow crops. Left over radiation while bad would mostly be localised and we are not talking about Fallout 4 type levels in 200 years. Certain nations (eg various Pacific Islands). would probably be unlikely to be even hit so the only real threat to them would be global effects.Extinction level event: Plausible but unlikely IMHO. Climate Change The world is getting warmer and where I live you can see it with your own eyes (glaciers are melting). While this is catastrophic for our current levels of consumption/economy and for certain parts of the world (desert nations, islands, coastal areas etc) its not an extinction level event. Humans will survive along with the right crops and animals. Humans survive in the tropics and deserts and the world has been hotter in the past and life survived. Its very bad news for certain species though.Extinction Level Event (for us). No.Asteroid Strike A genre of bad 90's movies current thinking is a large asteroid wiped out the dinosaurs and it could wipe out us. Apparently however that asteroid hit the exact right spot and had it landed somewhere else the dinosaurs would have survived. The effects were likely similar to a nuclear winter but on a global scale and it caused one of the 5 mass extinction events. A similar sized asteroid would have to hit the right spot, cause a nuclear winter type effect that would last long enough for our food stocks and supplies to run out. Even then something would survive (birds, sharks, crocs and cockroaches survived the Dinosaurs). Then again Earth might get hit by a bigger asteroid. To wipe us out you would need to duplicate the asteroid strike and assume that our technology could not divert it (a few degrees would cause a miss if caught early enough) or that out technology would not let humans survive for long enough for the atmosphere to clear which may have taken less than a year. The further away from the strike the better the chances of survival would be as presumably there were pockets last time around as some things survived.  ELE: Probably not.  Super Volcano. A super volcano is basically a very large volcano blowing up and causing climate change due to dust in the atmosphere. Humans have survived super volcanoes so in theory it would have to be a very large one. A popular candidate is Yellowstone National Park. Once again this feeds back into the nuclear winter thing with dust in the atmosphere blocking sunlight. Much like my previous entries this depends on how long the dust would last for and how bad the dust actually is. Volcanic activity can definitely render a planet uninhabitable but the scale required is massive, probably more than a single super volcano. Google Deccan traps or Siberian Traps to get an idea of the level of volcanic activity required. Life survived the Siberian ones although its possible it caused one of the previous mass extinction cycles. A single super volcanoes going up I don't see it wiping us out although it might cool the planet for a year or two causing crop failure etc. Extinction Level Event. No.  Super Disease Another popular one for a dooms day scenario. I don't really see any disease no matter how bad having a 100% kill rate along with a 100% infection rate which would be what is required to wipe out a species (or at least humans). I can't really see us engineering a bio weapon either that is that effective. Humans have survived smallpox, the black death, and various other plagues throughout history so yeah.ELE. No.  These are the most common scenarios you read about or movies are made about. All of the above scenarios are catastrophically bad but probably won't wipe us out as a species. Unlike animals we can bunker down in the short term or have stockpiled food stocks to survive- at least in the short term. I'm not talking about most of the population surviving, most households would be in trouble in a week or two but some people have bunkers, bolt holes, stockpiles etc so in theory someone would survive at least short term. So what would kill us off.1. Poisoning/Removing The Atmosphere. Global warming won't kill us but this will and some doomsday scenarios with climate change think that we might cause a run away greenhouse gas effect and turn the planet into Venus. Terra is far enough away from the sun I don't think that would happen. The world has been warmer before and all the C02 used to be in the atmosphere once upon a time so I don't really see that happening. I don't know how we could poison the atmosphere but if we do yeah we're in a lot of trouble.  Otherwise some sort of natural (or unnatural) catastrophe that destroys the atmosphere would do us in. The Earths magnetosphere keeps us safe from that, but if that goes (it will happen at some point) we're gone. 2. Poisoning the Oceans. Most of the previous mass extinctions seem to have hit the oceans very hard and the oceans seem to be the lifeblood of the planet. If we collapse the food chain in the oceans it will effect the land which could have flow on effects such as environmental impact that will last longer than a few months or a year or two.3. Snowball Earth One theory has it that the Earth froze over millions of years ago. Global warming would not do us in this might. Life did survive the last time round and there may have been a narrow band around the equator where life did survive. The last time this happened (650 mya maybe) the earths atmosphere probably was not breathable by humans anyway. 4. Future tech. This is a cover all for anything we invent in the future that we don't know how it works. This includes things like self aware AI (that wipes us out), fusion bombs (miniature super novas), anti matter bombs (blow the planet/continent up), nanites that consume the planets, or a death star super laser. Beats me its future tech, 200 years ago people probably didn't imagine nuclear weapons.</blockquote>

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