Humankind has had plenty of time to flex highly developed imaginations. During that time, theories and depictions of the world coming to an end have flourished. Outlandish apocalyptic imaginings typically come from zealots who are certain that they know exactly how the world will end.
But in realistic terms, the Earth is all but guaranteed to come to an end when the Sun expands into a red giant and swallows our planet. Thankfully, we have billions of years to figure out the puzzle of how to keep the Sun burning at a steady pace.
Of course, we need to keep ourselves alive long enough to develop that which is currently impossible. Meanwhile, a myriad of threats, both subtle and obvious, threaten our existence in a variety of ways. From destroying the population on a microscopic level to detonating cataclysmic explosions that can blot out the Sun, humankind seems intent on destroying itself before its time.
The truth is that the miracle of humanity's ascension to the top of the food chain could have been derailed at many points during history. But on every occasion, our violent intelligence has been applied to solve some of the greatest threats. Will humanity withstand these ten most pressing threats to avoid a worldwide apocalypse?
These figures have been compiled by scientists with the Global Challenges Foundation.
10 Global System / Ecological Collapse - <0.00003%
Humans beings are supported by all these systems that make it easy to live, some of which aren't immediately obvious. As a result, if any one system - ecological, political, even familial - suffers severe problems, they could all begin to collapse.
The world's ecosystem relies on a balance that is already being upset, as witnessed by the beginning of climate changes and newly extinct animals. The recent, severe decline in bee populations, which are vital for pollinating many important crops, is particularly concerning.
A complete collapse of either type of system would plunge humanity into an era of chaos, with potentially apocalyptic consequences.
9 Super Volcano - 0.00003%
During the early periods of the Earth's formation, severe seismic activity consistently threw the surface into upheaval. This eventually settled down to form masses of land that rose above sea level, allowing life to thrive on the surface.
Evidence of this process can be witnessed today around live volcanoes and other seismic features that rattle the planet and squeeze lava from far beneath the crust.
Scientists believe that a super-volcano eruption could actually end the world. It would need to be strong enough to release an ejecta over an area greater than about 1,000 square kilometers. This would end up not only destroying a significant portion of the world's surface, but would toss up enough dust and dirt to obscure the sun.
8 Global Pandemic - 0.0001%
One of the most unpredictable potential causes of an apocalypse is a global pandemic that simply cannot be stopped by modern medicine.
Pandemics have been responsible for population control throughout history. There was the bubonic plague, which reduced the population of the planet by one-third, and the Spanish influenza, which infected about 500 million people, killing between 10% to 20% of those who fell ill.
Current candidates for a modern pandemic include ebola, AIDS, H1N1 and other deadly diseases that could be a few mutations away from becoming airborne, increasingly virulent and resistant to medicine.
7 Asteroids - 0.00013%
NASA has discovered over 1,400 asteroids flying through our solar system that could end up impacting our planet due to their uncomfortable proximity to earth's path through outer space. Then, there's believed to be an untold number of large asteroids that are big enough to make a major impact that are still undetected.
Researchers believe that once every 20,000,000 years or so, an asteroid that exceeds five kilometers in length makes an impact on our planet. It releases the energy equivalent to 100,000 times the biggest bomb exploded by humans. This type of impact would destroy a country the size of Holland, or, if it lands in the ocean, create unprecedented tidal waves that would wipe out unthinkable amounts of coastline.
Similar to the super volcano scenario, the atmosphere would end up becoming obscured with dust and clouds of particles, blocking out the sun.
6 Nuclear Conflict - 0.005%
Despite nuclear non-proliferation agreements and treaties agreeing to reduce the amount of nuclear bombs that militaries stockpile, the collection of nuclear bombs said to exist are in excess of 20,500 warheads.
On average, each of these terrible devices measures 33,500 kilotons of explosive force, more than enough to destroy the surface of the planet.
However, it would probably be the radioactive fallout that would finish humanity as a whole, destroying organic life and ruining the earth's supply of fresh water. Also, similar to an asteroid impact and the potential for a super volcano, one of the most serious threats is blocking out the free energy that we receive from the sun.
5 Synthetic Human-Targeted Biology - 0.01%
The marvelous technologies of the future that promise to help make life better for us all may also be used against us to create our own demise. In the case of synthetic biology fashioned through genetic engineering, a simple mistake or a mad scientist bent on destruction could unleash an organism deadlier than a pandemic created by nature.
Few, if any, regulations currently exist to control genetically modified biology, which could wreck havoc on humanity through malicious intent or simple human stupidity. All it would take is something that ruins a vital part of our ecosystem or even destroys vital human genetics to unleash death and destruction on an unprecedented scale.
4 Extreme Climate Change - 0.01%
The earth is experiencing the hottest global temperatures on record, waves of disastrous weather, melting ice caps and rising ocean levels. Still, climate change deniers somehow believe that the earth is just going through a phase and will naturally balance itself out.
All of the above symptoms of climate change are terrifying and have already resulted in plenty of human suffering, but perhaps the scariest outcome would occur if the average global temperature rises by 7 degrees Celsius. About half of the earth's population would experience conditions that would make it impossible for human physiology to cool itself down by sweating during the summer, making the Eastern United States, parts of China and India completely uninhabitable.
A rise in average global temperature of 10C would end up making the majority of the populated earth uninhabitable due to limits of human physiology.
3 Nanotechnology - 0.01%
Nanotechnology is another fantastic human innovation that has the capacity to be both our savior and our executioner. The ability to control tiny machines that can manipulate tiny bits of matter at the cellular and molecular level may advance medical treatments that destroy diseases like cancer.
This technology could also create utopian technologies that remove pollution and toxins from the environment, even boosting agricultural output or making it cheaper and easier to manufacture the basics that humans need to survive.
However, nanotechnology could also be used as an unstoppable weapon that harms, instead of improves, vital human systems. Another potential issue with nanotechnology is uncontrollable replication that creates a grey death of tiny particles that flood the atmosphere.
2 The Fermi Paradox - 0.1%
Ever notice that life doesn't appear to exist anywhere else other than on our planet?
Scientists refer to this as the Fermi Paradox. Why is there an apparent lack of intelligent, alien life within our galaxy, including any sort of communication or transmission picked up by projects such as the Search for Extraterrestrial Intelligence?
One explanation is that our definition of intelligent life is limited to what we currently experience on our planet. The entire cosmos could potentially be intelligent, and we're just too arrogant and narrow-minded to understand the message. That message just might be that intelligent life tends to destroy itself before branching out and exploring the rest of the universe.
The Fermi Paradox is the philosophical question that scientists implore humans to ask themselves in the hopes of figuring out causes of a potential apocalypse.
1 Killer Robots - 0.1% to 10%
According to scientists, the most probable cause of the apocalypse is humanity creating, and then losing control of, artificial intelligence projects. AI researchers use human intelligence as both a benchmark and a template. Thus, there's a possibility of creating this type of technology in our own image. That image could end up replicating the darker side of human nature that craves power, avarice and dominance over other life forms.
Although artificial intelligence will likely actually end up helping to save humanity from its own folly. But there's also a small but not insignificant chance that AI becomes the superior form of life and works to eradicate what it would consider to be a parasitic blight upon the Earth - humankind.