Another week, another claim that the world will end. This time the doom and gloom came from the eBible Fellowship of Philadelphia, who said that on October 7, 2015, the apocalypse would begin. Well, it didn't. But let’s take this cheery occasion to look at some different ways the world could possibly end.
Death by Asteroid/Comet/Supernova
What better way to go than with destruction raining on us from the sky? A collision with a planetesimal – either a comet or an asteroid – could have devastating consequences, not just for the human race but for life on Earth as a whole. The principal cause of the Cretaceous-Tertiary extinction was the Chicxulub asteroid; it had an estimated diameter of 10 kilometers (6.2 miles) and released upon impact energy equivalent to 2 million Tsar bombs (the most powerful atomic bomb ever created). The extinction affected not only dinosaurs but 75% of living organisms present on the planet at the time.
An impact will release a huge amount of dust and sulfuric aerosols, or suspended particles, into the atmosphere, significantly reducing sunlight available for plants’ photosynthesis and lowering the surrounding temperature. With plants dying, the food webs will crumble, leading to an exponentially more challenging fight for resources. Fragments from the asteroid will be bounced back into the atmosphere and upon re-entry will spread global firestorms. Depending on the location of the impact, megatsunamis and plate-cracking earthquakes will spread the immediate devastation of the impact for thousands of miles.
Being aware of the potential danger is important, so major space agencies are preparing catalogs of Near Earth Objects (NEOs) that they can monitor. Scientists believe that almost all NEOs over 1 kilometer (0.62 miles) have been identified, but tinier objects may still be eluding detection. But worry not, NASA and ESA are planning to test our asteroid deflection capabilities.
A supernova explosion, depending on its proximity to the Solar System, might be severely more damaging. If the Sun were slightly more massive, it would eventually go supernova, and the amount of light an earthly observer would see is equivalent to having a billion hydrogen bombs detonating directly onto your eyeball, based on the average energetic output of a supernova and the average yield of an atomic bomb. Although supernovae are terrifying, we are quite safe from them. The closest star that we believe will go supernova soon (in cosmic time) is Betelgeuse and it is a cozy distance away.
Death by Supervolcano
A supervolcano is any volcano capable of ejecting more than one trillion tons of material during an eruption. That mass is the equivalent of about 100 Mount Everests. Their eruptions are formidable geological events that occur when the magma from the Earth's mantle can’t find a way to escape through cracks in the crust. The resulting pressure build-up is so great that the eruption has far-reaching effects.
Supervolcanos are able to cover enormous areas with ash and lava and can significantly affect the entire world climate, generating mini ice ages or global warming. Volcanic winters have happened in recorded history, the most recent of which occurred in 1991, when Mount Pinatubo's eruption in the Philippines led to a worldwide cooling.
The most famous supervolcano is probably Yellowstone. It has a caldera, or post-eruption depression, that measures 55-by-72 kilometers (34-by-45 miles). In its last eruption 640,000 years ago, ash spread from North Dakota to Louisiana and California.
Supervolcanos might have played a role in several extinction events throughout Earth’s geological history, but even the most powerful known volcanic eruption (which formed La Garita Caldera, located in modern-day Colorado) delivered only 0.24% of the energy of the Chicxulub impact.
Death by Pandemic
The end of the world doesn’t have to mean the death of all living creatures on the planet. Bacteria and viruses could easily show us the door by evolving more deadly or more easily spreadable versions of the diseases we are currently fighting.
Historically, the most devastating pandemic was the Black Death. Caused by a bacterium and spread by fleas, in just seven years (from 1346 to 1353) the plague moved from central Asia to Northern Europe, killing in its passage between 75-200 million people. The plague continued to kill in Europe until the 19th century. Another notable example is the Spanish flu that between 1918 and 1919 managed to kill over 75 million people worldwide.
Future pandemics are a serious threat to humanity. We understand better the cause of infectious diseases and how they spread, but there might be political, economic and social struggles in the prevention of pandemics. The ability of humans to quickly travel around the planet could accelerate the spread of bacteria and viruses, as well as our inability to recognize new diseases by standard symptoms. The adaptability of viruses that could lead to accelerated contagions and the rise of antibiotic-resistant bacteria are significant hurdles that medical researchers are working tirelessly to understand and solve.
Death by Self-Destruction
If you want something done right, do it yourself. Why wait for asteroids, volcanos or diseases when we can simply do the job ourselves? Twenty-six years from the end of the Cold War, an all-out worldwide nuclear conflict is still the more efficient way to get rid of all mankind. To the best of our knowledge, there are about 16,000 nuclear weapons in the world. If they were used all at once (assuming a 50 megaton yield per weapon), they would generate an amount of energy three times larger than the La Garita supervolcano (125 times less powerful than the asteroid that killed the dinosaurs), which is a powerful result. Not only could we produce quicker climatic changes than we are already doing, but radiation will guarantee a widespread extinction event.
People might imagine the world without us a desolate, dark land, but while specific organisms are inherently weak, life is resilient. From the radiotrophic fungi that survive inside the Chernobyl nuclear reactor to the extremophile bacteria living near volcanic vents at the bottom of the ocean, the world is full of stubborn species. Jellyfish, sharks, frogs and crocodiles were here before dinosaurs and they are still around. And if we kill each other off, they might even outlive us.
Death by Robot Uprising
A scenario that most people think is likely for our demise: a robot uprising. It probably originates from anti-technology sentiments dating back to the Industrial Revolution, but owes it success to movies like "The Terminator" and "The Matrix," which have cemented the idea in our shared consciousness. Technological advancements in producing faster and better robots and computers are incredible, but there is a long way to go before we create a truly thinking machine. And even at that point, human beings will not suddenly become obsolete.
Computers, like most machines, were not created to replace us but to fill a void of ability. Steam engines were needed to move many people quickly, computers to do complex calculations, and robots to help with tasks that humans either can’t or won’t do. The advent of thinking machines won’t herald the destruction of humanity nor its salvation. It will change the world, but in mundane rather than cataclysmic ways.
And for the people that believe thinking machines are already watching us, I bring autocorrect as evidence of this not being true. Unless it’s a clever ruse by the cyborgs. In that case, I for one welcome our new robotic overlords.
