Top 10 Craziest Ends to Civilizations As We Know It

10.  Super-diseases

The theory of natural selection is simple but brilliant; traits which lead to survival are passed on to the next generation, while traits which would hinder an organism’s ability to survive tend to die out.  Natural selection has gifted us humans with plenty of fantastic advantages over other animals, such as opposable thumbs, highly-developed brains and…well…we do have nice thumbs and brains.  Where things get ugly is when natural selection is applied to nastier organisms, like poisonous snakes, insects, lawyers…and humanity’s eternal foe, bacteria.
Mankind’s development of antibiotics has been, in recent history, to great effect against a great range of malevolent microorganisms, killing off the hostile bacteria before they can spread and damage your body.  A side effect of this, however, has been something observed by scientists as “antibiotic resistance.” This is pretty much exactly what it sounds like: subjected constantly to the trial-by-fire of antibiotics, the bacteria must continue to evolve to resist more and more antibiotics, slowly evolving into millions of tiny versions of the Terminator.
With the number of new medications being developed dwindling due to a marked decrease in medical R&D, it could only take an unfortunately lethal bacterial strain with antibiotic resistance to leave civilization as we know it choking and coughing for breath.
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9.  Geomagnetic Reversal

Every 10,000 years or so, the Earth’s magnetic poles have switched, an event known as a geomagnetic reversal.  This is extremely likely to be accompanied by a greatly diminished magnetic field, opening the Earth up for a bombardment of cosmic radiation.  While this is unlikely to harm us humans, the real danger lies in how it affects our technology.  If electricity and communications grids are damaged or disrupted, a real risk exists that the technology our society is constructed upon could temporarily cease to function.
Aside from the more obvious implications of this, such as life support systems failing and water pumps breaking down, the real risk here comes from ourselves.  During blackouts of the past, such as the New York blackout of 1977 (which lasted only two days), city-wide looting and chaos reigned.  What would happen to civilization if the blackout was global, and lasted for longer than a few days?
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8.  Ecological Disaster

It’s sometimes easy to forget just how much we depend upon our ecosystem to survive.  A phenomenon termed “colony collapse disorder”, where worker bees simply disappear from hives, could very possibly prove a major disaster for world-wide food supplies, which depend upon these bees to pollinate critical crops food-providing crops.  In short, bitches bee crazy.
Other (less exciting) examples include things like pollution, overfishing and deforestation; or pandemics among cultivated plants.  As our population grows and food shortages become more problematic, a sudden disruption in a major source of food could result in mass starvation, not to mention the associated fear and violence which could be caused by such a disaster.
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7.  Hypercane

A hypercane is an awesomely-named, hypothetically massive tropical cyclone resulting from increased ocean temperatures.  Such increased temperatures could be caused by things like volcano eruptions or asteroid impacts, or by more mundane causes such as global warming. Computer models have demonstrated that, if oceans were warmed to a temperature of 45 or 50 degrees C, winds averaging an astonishing 600 kilometres an hour could be produced.  Even more staggering is the size of these hypercanes, which are theoretically massive – we’re talking size-of-North-America massive, and with an exceptionally long lifespan to boot.
Hypercanes have been used as an explanation for mass extinctions in the past, where huge numbers of species have been wiped out at a time; who is to say it couldn’t happen again? In today’s highly-connected global civilization, even if only a single continent were effected, the implications could be massive.
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6.  Coronial Mass Ejection

A coronial mass ejection is like a solar flare on steroids.  While these are harmless to humans, they are capable of knocking out electrical systems and destroying silicon-based computer parts, essentially crippling civilization as we know it.  We live in an age where everything from cars to phones contain computer parts, and all of these contain silicon – the implications such an event could have on our society are enormous.
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5.  Megatsunami/Supervolcano

A megatsunami is one of those things which is exactly what it sounds like: a tsunami big enough to destroy, for instance, the entire East Coast of the US, caused by huge impacts such as cosmic collisions, massive earthquakes and more disturbingly, large landslides.  The devastating effects which such a huge tsunami would cause are pretty obvious, and there’s very little we can do to prepare for such an event.
For a bonus disaster, a somewhat similar geographic world-changer is known as a supervolcano. Their less-than-creative name is nonetheless pretty accurate; these volcanoes are so big that their eruptions are literally thousands of times larger than that of an ordinary volcano, and are big enough to literally bury global civilization (from both the vast eruption itself, and the huge dust clouds likely to be kicked up). T here are about seven in the world, and any of them could theoretically awaken at any time.  Sleep well!
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4.  Biotechnology Disaster

No, we’re not talking zombies here.  There have been cases recorded were genetically-modified crops have crossbred with competing weeds, resulting in pesticide-resistant, fast-growing superweeds (not the kind which get you superstoned), which could in turn result in an agricultural and economic disaster of a massive scope.  Even more frightening is the possibility of the misuse of biotechnology in creating dangerous and resilient diseases, pests and weeds.  This could be done deliberately as a means of bioterrorism or accidently by some overzealous idiot in a lab coat, if disaster movies have taught us anything.
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3.  Gulf Stream Shutdown

The Gulf Stream is a huge global current, which carries warm water northwest across the Atlantic Ocean, warming Western and Northern Europe.  However, global warming is causing problems for this (and just about everything else in the world) – by heating and melting ice caps into the Gulf Stream, global warming ironically slows it down, and there is evidence that if the trend continues it could eventually totally stop.  As well as making Europe even colder and greyer than it already is, this could result in disasters ranging from huge climate changes (including massive storms) to a mass phytoplankton extinction (you may recognise phytoplankton as the things which everything else eats).  Did we mention Europe was cold enough already?
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2.  Methane Burps

Perhaps the most deceptively-named item on this list, methane burps are far from as harmless as they sound.  Also (more suitably) known as “the Clathrate Gun Hypothesis,” this is an event where unbelievably huge amounts of methane previously contained in deposits in the ocean floor or permafrost are suddenly released into the atmosphere.  As methane is a much better greenhouse gas than carbon dioxide, this results in massively increased global warming.  Even worse, this temperature increase causes other “methane burps,” compounding the effects to terrifying (and deadly) heights.
The good news is that it’s only ever happened twice before, so it’s an incredible rare event.  The bad news is that when it does happen, everybody is pretty much screwed.  Think of it as a time bomb, and hope you’re not alive to see it go off.
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1.  Nanotechnology Crisis

The crux of nanotechnology is taking philosophy that “smaller is better” and applying it to robots, to serve all sorts of useful tasks, including repairing themselves and replicating.  Nanotechnology has some incredible implications in our everyday lives, from healing ourselves and maintaining our health to creating clothes which never require cleaning.  As with all great things (such as chocolate, alcohol and arson), this has the potential to harm people greatly.  Such versatile technology has the power to backfire and create all kinds of civilization-crippling problems, especially when one considers the possibility of deliberate misuse of this technology.
Perhaps the most terrifying possibility is that of so-called “Grey Goo” – an out-of-control mass of self-replicating nanobots which consume all of the matter on Earth while constructing more of themselves.  The scenario is perhaps best explained by molecular nanotechnology pioneer Eric Drexler: “Imagine such a replicator floating in a bottle of chemicals, making copies of itself…the first replicator assembles a copy in one thousand seconds, the two replicators then build two more in the next thousand seconds, the four build another four, and the eight build another eight.  At the end of ten hours, there are not thirty-six new replicators, but over 68 billion.  In less than a day, they would weigh a ton; in less than two days, they would outweigh the Earth; in another four hours, they would exceed the mass of the Sun and all the planets combined?—?if the bottle of chemicals hadn’t run dry long before.”