Though it may seem like a disaster that only happens in Hollywood, asteroids do come close, and it's likely that one day Earth will be struck by an object large enough to wipe out the planet's populations. Don't worry, though -- it may be 250,000 years before it happens, and a lot will have changed by then!
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While global warming can't be denied, there's no evidence that it's going to take out humanity anytime soon. It would require a lot of warming to create a greenhouse effect large enough to cause mass destruction, and fortunately, we're not there yet.
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Those who live in cities know how unpleasant it is to breathe in manmade pollutants on smoggy days. From industrial plants pumping chemicals into the air to farmers spraying toxic chemicals on the produce we eat, could pollution be what eventually takes us out?
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The nearest black hole is approximately 1,600 light-years away: not a threat anytime soon. However, if one ever happened to be passing by our solar system, it could wreak havoc from disrupting the planets' orbits to sending Earth spinning out into space.
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Speaking of space threats, some scientists have proposed the Big Rip theory, which basically says that the acceleration of the expansion of the universe would cause everything -- including Earth -- to be ripped apart. Just don't hold your breath for the next 750 million years to see if this actually happens!
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Movies like Contagion inspire fear in germophobes and doomsday-sayers alike. If an incurable disease caused a pandemic that traveled quickly around the world, would doctors and other experts be able to stop its spread in time?
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Remember the story of Noah's ark, in which God wiped out most of humanity with a flood and left only a few men standing? Whether you believe or not, many religious leaders agree that we can never know when an act of divine intervention might occur or what it could do to the Earth.
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From America's Mount St. Helens to Indonesia's Mount Merapi, we've definitely seen some impressive volcanic eruptions. But could a verneshot, or a massive volcano caused by gas buildup deep in the Earth, be enough to wipe out every population on Earth over a short period of time?
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Even as advances in medicine seem to be improving physical health around the world, mental health is suffering. Mental illness has increased in recent years, and while it's extremely unlikely to reach the point where it affects everyone, a world full of mass suffering would be a dangerous place.
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Different species are declared endangered or extinct each year. But could the loss of one tiny species, such as the golden toad, be enough to set off a chain of events that leads to the collapse of an entire ecosystem? Even the smallest bugs and bats serve a purpose in the food chain, and removing one species could potentially damage many others, including plants.
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Scientists create genetically engineered crops to be hardier and even healthier. But how could these not-so-natural crops affect the ecosystem over time? Can the manufactured genes find their way into the various species that eat the crops, and if so, what if a dangerous mutation started to spread?
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Solar flares, or powerful magnetic outbursts on the sun, are counteracted by Earth's atmosphere and aren't a potential threat. But astronomers have observed other sun-like stars experiencing superflares, millions of times stronger -- and deadlier -- than the ones on our sun. Hopefully, since our sun is aging, its potential superflaring days are long past.
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Pollution is unpleasant, unhealthy and ugly as it smogs up our cities. But what if it reached the point of global dimming, where pollution levels where so high that they blocked out the sun? A sunless world would be deadly over time, not to mention extremely depressing even in the short term.
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Speaking of dimming -- what if the sun itself shone less brightly? If the sun went through a period of low brightness, it could potentially cause the Earth to freeze, killing everything off over time. This is unlikely to happen for millions or billions of years, though, so don't reach for that thick coat just yet.
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Gamma-ray bursts, which are probably caused by the merging of two collapsed stars, are intensely bright and powerful -- almost more so than we can imagine -- and a gamma-ray burst nearby would destroy the Earth's atmosphere. Luckily, none of the types of stars that have been determined to cause these bursts seem to be close enough to harm us.
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Every so often, Earth's magnetic field reverses, the last event being around 780,000 years ago. Apparently, we're due for a reversal in the next hundred thousand years. However, even if this were to happen while humans still walked the planet, it's not certain that it would be a deadly event.
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According to the Clathrate Gun Hypothesis, rising sea temperatures would release natural gases from methane clathrate, a form of water ice. This would cause higher sea temperatures, causing more methane release, and so on. This chain reaction could wreak havoc over time, since methane is much more powerful as a greenhouse gas than carbon dioxide.
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With active nuclear warheads floating around, it's hard to permanently dispel the fear that nuclear war could be a threat again one day. As long as there's political unrest, there's the potential for humans to create -- and use -- deadly weapons.
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And speaking of weapons of mass destruction, who knows what the next manmade superweapon will be? If we can invent a weapon with the power to wipe out thousands at a time, can we come up with something that wipes out entire continents?
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Maybe more likely than a deadly bomb is the possibility of widespread biowarfare. Because biological weapons, like engineered germs or diseases, are easier to conceal than massive bombs, they have the potential to spread faster and could be difficult to stop once they're out of control.
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We may scoff, but the universe is seemingly infinite -- who knows what other life forms are out there? What if intelligent aliens are making their way to Earth right now, looking for a new planet to take over and new beings to control? If they're smart enough to get here, they'll probably be smart enough to destroy or overpower humanity.
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Aliens aside, what if something equally dangerous came from space? Maybe we've avoided an asteroid, but an explosion causes debris to rain down on our planet, bringing with it an unknown virus or disease that we can't control. Unlikely, but again, the universe is a mysterious place!
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From Terminator to AI: Artificial Intelligence, movies have long depicted cyborgs that look shockingly human. Is it possible for humans to create robots with enough intelligence to stage a takeover? Intelligence without compassion seems like a pretty scary combination.
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Remember the particle accelerator in Angels & Demons? It was based on the Large Hadron Collider in Switzerland. While some worry that such powerful machines could potentially create black holes that would eat up Earth's atmosphere and destroy us all, scientists point out that the planet is hit regularly with cosmic rays more powerful than those in particle accelerators -- and we're still here.
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It might seem like a nice idea to be able to control when it rains or snows, but what if it were possible to control the weather on such a scale that we could create hurricanes, tornadoes or worse? Climate modification could have serious consequences, whether superstorms were created by accident or on purpose -- for use as deadly weapons.
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There are scientists who believe that time travel could be a real possibility. But even if it were possible, would we really want to use it? One misstep by someone who revisits the past -- say, a destroyed species -- could have disastrous results for the future of humanity.
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Engineers in the field of nanotechnology are working on creating microscopic robots with the potential to build products or perform surgery inside a patient. It may even be possible to create tiny robots that can assemble and replicate themselves. But like larger forms of artificial intelligence, could these tiny robots wreak havoc even where they were meant to do good?
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Chemical warfare obviously carries many dangers, but think about this one -- what if chemicals caused sterility? Even if it were a gradual process, the possibility of fewer new humans entering the world every year would eventually lead to, well, no humans at all.
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From Night of the Living Dead to The Walking Dead, zombie movies and TV shows seem to hold a strong fascination for viewers around the world. While it's unlikely that the dead will ever come back to life, there could be a pandemic of a disease causing zombie-like traits in those who contract it. Kind of makes you shudder, doesn't it?
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Could apes rule the world? In the original Planet of the Apes movie, they were the future of our planet. In the latest ape flick, Rise of the Planet of the Apes, genetically enhanced chimpanzees attempt to take over. OK, so it'll probably never happen, but with advances in the field of genetic engineering every day, who knows what could happen next?
Now that you've looked through some pictures of the apocalypse, how do you think the world will end? Test your End of Days knowledge by taking our Apocalypse Now Quiz