Here comes mass extinction number 6—and guess who's the cause?

The sixth extinction isn't just an X-Files episode. It refers to the latest in a string of "extinction-level events"—epic die-offs that this planet has experienced over the past 540 million years.

Theorized causes of the previous five extinctions include asteroids, sea level changes, a series of volcano eruptions and even gravitational disturbances. But the upcoming sixth extinction has a definitive villain: us.

Researcher Elizabeth Ferrar says that humans have killed off animal species with our pollution, destruction of animal habitats and overfishing.

To be clear, the death of a few species isn't an "extinction-level event." An ELE means "Take 50 percent of all animals on land and sea, then kill them. "

According to Yahoo, to determine whether we're undergoing an actual extinction event, researchers asked, "Is the pace of extinction we're seeing today over these short time intervals usual or unusual?"

They found that the overall rate of extinction is, in fact, between three to 80 times higher than non-mass extinction rates. Most likely, species are going extinct three to 12 times faster than would be expected if there were no crisis, Ferrer said.

That gives Earth between three and 22 centuries to reach the point of mass extinction if nothing is done to stop the problem.

The fifth extinction occurred 65.5 million years ago and wiped out every dinosaur alive. (We're not even going into the 16 lesser extinctions that have occurred over the eons.) According to scientists, the sixth extinction should be happening sooner—within 300 to 2,000 years.

Geologically speaking, that's any second now. Even worse, an article in the journal Nature suggests that a mass extinction is happening at this very moment.

But before you start playing "Taps" for life on the planet, we can prevent this by cutting down on fossil fuel usage and promoting conservation and biodiversity. So, yay.

If we can only prevent asteroid strikes and volcano explosions, we should be safe from the alternate sixth extinction.

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