Frightening Existential Risks to Life on Earth


A global catastrophic risk is a hypothetical future event which could lead to the destruction of modern civilization, mass extinction, or the destruction of the planet entirely. Earth’s geological record is filled with asteroid impacts, climate shifts, ice ages, super volcanoes, and extinction–lots of extinction; but the greatest risk to life may not come from anything terrestrial.

Here are 10 of the most terrifying existential risks to life on Earth.

10. Warfare and Weapons of Mass Destruction

In 1983, the Soviet Union’s nuclear early warning system reported the launch of multiple USAF Minuteman intercontinental ballistic missiles from US military bases. The only thing that saved us from having our skies bathed in nuclear fire, was officer Stanislav Petrov’s gut feeling that the warning was a false alarm

John F. Kennedy once estimated the odds of all out nuclear warfare happening to be “somewhere between one out of three and even.” American Cryptologist Professor Martin Hellman has claimed that nuclear war is inevitable. The United States and Russia have a combined arsenal of 14,700 nuclear weapons, and the total world supply ranges in the high 15,000s. 

Though Cold War studies estimated that billions of people would survive the initial conflict, the debate rages on whether or not secondary effects such as, nuclear winter, radiation sickness due to fallout, and unforeseen environmental effects could contribute to the total extinction of life on Earth.

A 2008 survey by the Future of Humanity Institute estimated a 4% probability of extinction from warfare by 2100, with a 1% chance of extinction from nuclear warfare.

Other forms of warfare, such as biological and chemical warfare also carry their own risks—though chemical warfare has a significantly lower chance of threatening life on Earth as a whole. 

9. Biotechnological Disaster


In 2008, a survey made by the Future of Humanity institute estimated a 2% probability for life on Earth to go extinct due to the accidental release of a biologically modified organism. The increasing accessibility of technologies which allow us to modify the characteristics of viruses and other biological agents has lead to an increased risk factor that such agents could be accidentally released into our environment, having devastating effects on eco-systems they come in contact with.

In 2001, researchers attempting to sterilize rats by developing a new virus accidentally modified it instead. The modified virus became extremely volatile to the mice, even to those that had already been vaccinated.

Following the rapid developments in CRISPR editing (editing of DNA sequences found in genomes of organisms like bacteria and archaea), an international summit proclaimed in December 2015 that it was “irresponsible” to proceed with human gene editing until safety measures and efficacy could be addressed.

8. Nanotechnology

In K. Eric Drexler’s 1986 book Engines of Creation, the nanotechnology pioneer outlines a terrifying scenario where the accidental creation of nano-machines that consume organic matter as a means of energy production end up devouring all life on Earth. While this idea that such an event could be accidental has been rejected by modern day experts in the field, there is still quite a bit of existential risk with the emerging development of nanotechnologies

While there is a plethora of benefits to the development of nanotech such as automation, medical advancement, and manufacturing, there are also risks in those same areas. It has been argued that the emergence of these technologies could lead to a new arms race. Since nanomachines are so small, and factories of them could take up as little space as a small desktop, it would be incredibly difficult for governments to regulate their use or production. It has been noted that nanotech would be extremely beneficial in medical procedures, but the same could be said of warfare. Nanomachines would be capable of entering the bodies of enemy combatants or civilians without their knowledge and be just as effective at killing the subject as they would be in other medical procedures.

7. Artificial Intelligence

Stephen Hawking, Elon Musk, and Bill Gates have argued that the rise of super intelligent machines would spell certain doom for humanity; and it all comes down to control. We’re already seeing automation take hold in many industries. The robots that serve us may not be intelligent enough to pose a threat yet, but what happens when A.I. surpasses human intelligence? Would it see us as obsolete? Would it seek to eradicate us? 

Most of you are probably thinking of Terminator style machines or A.I. controlled drones hunting humans down in the trenches of a post nuclear wasteland—and while that’s certainly a possibility—the threat could take a very different form than what’s offered by Hollywood science fiction films. More and more systems are becoming automated, relying on basic A.I. to do rudimentary things. What happens when this automation extends to medical equipment, or when computer viruses become able to self-adapt to counter measures, or if super intelligent machines gain the ability to build even greater artificial intelligences?

Science fiction author and computer scientist Vernor Vinge suggested that the moment when humanity creates an intelligence greater than itself is the very moment when the human era will end, calling it the Singularity. 

6. Mineral Resource Exhaustion

In the last decade, the price of helium has gone up more than 250%. One of the world’s biggest supplies of the element, the Federal Helium Reserve, has seen its supply gradually depleted over the course of the last decade, and it is estimated that it will sell off its remaining supply by 2021. Helium is used in vital medical technology, arc welding, and to pressurize liquid fueled rockets, and while it’s one of the most common elements in the known universe, it’s extremely rare on Earth. 

Scientific data seems to suggest that humans are living far beyond the carrying capacity of our planet. In July 2015, the official United Nations World Populations Prospects was revised, stating that the population would swell to 8.5 billion by 2030. And as of February 2020, we are currently sitting at 7.7 billion people worldwide. 

Due to the increased demands on the Earth’s resources accompanying the increase in population, scientists and researchers suggest that it is not a matter of “if” but “when” those resources will dry up.

5. Natural Climate Change

It has been proposed that at one point in the distant past, ice covered the entirety of the Earth, exterminating all life on the surface. Causes suggested for this “snowball earth” have ranged from space clouds (dust and particle clouds that could have at one point blocked out the sun), a lowering of greenhouse gases, to a much dimmer sun. 

Ice ages dominate the majority of Earth’s timeline. Interglacial periods are dwarfed by long stretches of time where the ice sheets rule the surface of the planet, and can be attributed to variations in the Earth’s orbit, diming and brightening of the sun during its natural cycles and processions, as well as extraterrestrial events such as cataclysmic bombardment by asteroids—which can drastically increase the Earth’s temperature. The average duration of an interglacial period is around 10,000 years.

The last ice age was more than 11,000 to 17,000 years ago. 

It’s worthy to note that a modern ice age would have a drastic effect on human civilization. It would disturb many industries, shrink useable land for crops, and it’s possible that such an event would cause civilization to implode entirely. To exactly what extent, though, is debatable.

What isn’t debatable, however, is that if another snowball earth scenario were to happen in modern times, all life on the surface of the Earth would go extinct.

4. Extraterrestrial Invasion

While there is no current evidence to support the existence of extraterrestrial life, many prominent astronomers and scientists (such as Carl Sagan) have suggested that it is highly likely, and in 1969, the “Extra-Terrestrial Exposure Law” was added to the US Code of Federal Regulations in response to the possibility of biological contamination resulting from the Apollo program. 

While unlikely, it is possible that if extraterrestrial life exists, it could find us, and invade the Earth, thereby exterminating and replacing human life, stealing our resources, terraforming the planet to serve its/their own needs, enslaving us, or destroying the planet altogether.

Stephen Hawking suggested that we should be wary about answering messages from potential alien civilizations. If such a civilization were to view us as inferior, and if they were far more technologically advanced, there’s no telling what they might be able to do to us.

3. Cosmic Threats

In April 2008, it was announced that two simulations of long-term planetary movement, one at the Paris Observatory and the other at the University of California, Santa Cruz, indicate a 1% chance that Mercury’s orbit could be made unstable by Jupiter’s gravitational pull sometime during the lifespan of the Sun. If this were to become a reality, the simulations suggested a collision with Earth could be one of four possible outcomes. And if that were to happen, then all life on Earth would be wiped out. Period.

Last year, we took the first ever photo of a black hole at the center of galaxy M87. And it’s theorized that smaller black holes are fairly common in the universe. Recently, ALMA (Atacama Large Millimeter/submillimeter Array, a set of 66 telescopes scattered across the Atacama Desert in northern Chile) thought they might have discovered a wandering black hole about the mass of Jupiter in our galaxy. It’s thought that wandering black holes are rare, but if such a black hole were to wander into our solar neighborhood, the effects would be disastrous.

Then there’s the possibility of gamma ray bursts frying the Earth, vacuum decay causing the conversion of our universe to a lower energy state at the speed of light—destroying everything we love without any forewarning, massive solar flares or super storms that could cook us, and inevitably, the gradual expansion of the Sun’s radius into a red giant where it comes to dominate the sky and boil our oceans if it doesn’t consume the planet entirely (luckily, that last one won’t happen for billions of years). 

If that doesn’t make you feel like an insignificant piece of star dust, I don’t know what will.

2. Asteroid Impact

66 million years ago, the Chicxulub asteroid slammed into the Earth, killing the dinosaurs and causing the Earth’s global temperature to rise by 5 degrees Celsius, a change that persisted for 100,000 years. 

Recently, the Chelyabinks meteor exploded over Russia with a blast that was stronger than a nuclear explosion, injuring around 1,200 people. 

Scientists often describe our solar system as a “shooting gallery,” and it should be no shock that NASA has discovered well over 15,000 documented near-earth objects. The most troubling of these may be Atira asteroids, which is a class of asteroids which orbit too close to the sun to be easily detected. Such an asteroid, named LF-6 is a world ending object that has the fastest known orbit of any object in the solar system. Its orbit also intersects Venus’, and it is possible that interactions with Venus’ gravity could one day alter the asteroid’s orbit, sending it on a collision course with the Earth.

What’s most terrifying about the possibility of an asteroid hitting the Earth is that there’s no viable plan to divert or destroy a planet ender. Nuclear weapons have, in the past, been proposed, but new research suggests that not only would nukes be largely ineffective, but they could actually make the situation even worse by breaking a massive asteroid into large chunks.

1. Environmental Disaster

The Holocene extinction is the sixth mass extinction event, and it’s ongoing, measuring the mass die offs of mammals, birds, amphibians, reptiles, arthropods, and plants, at a rate of 100 to 1,000 times faster than previously established natural background rates since the end of the last ice age.

Some of these mass extinctions have been attributed to the hunting patterns of early humans, as they expanded their numbers, as the extinctions do match up with the steady growth of human populations and the rise of the civilization. However, there is some debate as to how much human hunting activity contributed to the extinction of megafauna and massive land mammals like the Woolly Mammoth.

One of the contributing factors could be climate change and ocean acidification.

Ocean acidification is known as global warming’s ugly twin. For nearly 200 years, the ocean has absorbed more than 150 billion metric tons of carbon from human activities, resulting in a record lowering of the average PH level for ocean waters. Risks associated with more acidic oceans include the extinction of biologically diverse habitats such as coral reefs, and marine life.

And then there’s colony collapse disorder. Measured in the early part of the 21st century, CCD is a phenomenon that occurs when almost all the worker bees in a colony vanish, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. 

Bees help to pollinate 35% of the world’s food sources, and current estimates suggest that 25% of bumblebees in the US are at risk of extinction. Habitat loss, pesticide use, and disease are thought to be causing the decline.

Environmental disasters like these could very well be accelerating the mass extinction of life on Earth, and scientists give us a decade to solve this problem before we cross the point of no return.

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