An extinction-level event can wipe out most species on Earth due to catastrophic conditions.
Potential extinction causes include solar flares, meteor impacts, volcanic eruptions, and human activities.
If you’ve watched the movies “2012” or “Armageddon” or read “On the Beach,” you know about some of the threats that could end life as we know it. The Sun could do something nasty. A meteor could strike. We could nuke ourselves out of existence. These are only a few well-known extinction level events. There are so many more ways to die!
But first, what exactly is an extinction event? An extinction level event or ELE is a catastrophe resulting in the extinction of the majority of species on the planet. It’s not the normal extinction of species that occurs every day. It isn’t necessarily the sterilization of all living organisms. We can identify major extinction events by examining the deposition and chemical composition of rocks, the fossil record, and evidence of major events on moons and other planets.
There are dozens of phenomena capable of causing widespread extinctions, but they can be grouped into a few categories:
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The Sun Will Kill Us
If a strong solar flare hit the Earth, the results could be devastating.VICTOR HABBICK VISIONS, Getty Images
Life as we know it wouldn’t exist without the Sun, but let’s be honest. The Sun has it out for planet Earth. Even if none of the other catastrophes on this list ever happen, the Sun will end us. Stars like the Sun burn brighter over time as they fuse hydrogen into helium. In another billion years, it will be about 10 percent brighter. While this might not seem significant, it will cause more water to evaporate. Water is a greenhouse gas, so it traps heat in the atmosphere, leading to more evaporation. Sunlight will break water into hydrogen and oxygen, so it can bleed away into space. Should any life survive, it will meet a fiery fate when the Sun enters its red giant phase, expanding out to the orbit of Mars. It’s not likely any life will survive inside the Sun.
But, the Sun can kill us any old day it wants via a coronal mass ejection (CME). As you can guess from the name, this is when our favorite star expels charged particles outward from its corona. Since a CME can sent matter any direction, it doesn’t usually shoot directly toward Earth. Sometimes, only a tiny fraction of particles reach us, granting us an aurora or a solar storm. However, it’s possible for a CME to barbecue the planet.
The Sun has pals (and they hate Earth, too). A nearby (within 6000 light years) supernova, nova, or gamma ray burst could irradiate organisms and destroy the ozone layer, leaving life at the mercy of the Sun’s ultraviolet radiation. Scientists think a gamma burst or supernova might have led to the End-Ordovician extinction.
02
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Geomagnetic Reversals May Kill Us
Scientists believe magnetic pole reversals were involved in some past mass extinctions.siiixth, Getty Images
The Earth is a giant magnet that has a love-hate relationship with life. The magnetic field protects us from the worst the Sun throws at us. Every so often, the positions of the north and south magnetic poles flip. How often the reversals occur and how long it takes the magnetic field to get settled is highly variable. Scientists aren’t completely sure what will happen when the poles flip. Maybe nothing. Or maybe the weakened magnetic field will expose the Earth to the solar wind, letting the Sun steal a lot of our oxygen. You know, that gas humans breathe. Scientists say magnetic field reversals aren’t always extinction level events. Just sometimes.
03
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The Big Bad Meteor
A big meteor impact could be an extinction level event.Marc Ward/Stocktrek Images, Getty Images
You may be surprised to learn the impact of an asteroid or meteor has only been connected with certainty to one mass extinction, the Cretaceous-Paleogene extinction event. Other impacts have been contributing factors to extinctions, but not the primary cause.
The good news is that NASA claims about 95 percent of comets and asteroids bigger than 1 kilometer in diameter have been identified. The other good news is that scientists estimate an object needs to be about 100 kilometers (60 miles) across to wipe out all life. The bad news is there are another 5 percent out there and not much we can do about a significant threat with our present technology (no, Bruce Willis cannot detonate a nuke and save us).
Obviously, living things at ground zero for a meteor strike will die. Many more will die from the shock wave, earthquakes, tsunamis, and firestorms. Those that survive the initial impact would have a hard time finding food, as the debris thrown into the atmosphere would change the climate, leading to mass extinctions. You’re probably better off at ground zero for this one.
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65 million years ago, a meteor struck the Mexican Yucatan peninsula, throwing tons of dust in the air and contributing to mass extinctions.MARK GARLICK/SCIENCE PHOTO LIBRARY, Getty Images
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65 million years ago, a meteor struck the Mexican Yucatan peninsula, throwing tons of dust in the air and contributing to mass extinctions. MARK GARLICK/SCIENCE PHOTO LIBRARY, Getty Images
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