Will Humans Survive the Sixth Great Extinction?
Species are disappearing at an alarming rate, a new study finds
In the last half-billion years, life on Earth has been nearly wiped out five times—by such things as climate change, an intense ice age, volcanoes, and that space rock that smashed into the Gulf of Mexico 65 million years ago, obliterating the dinosaurs and a bunch of other species. These events are known as the Big Five mass extinctions, and all signs suggest we are now on the precipice of a sixth.
Except this time, we have no one but ourselves to blame. According to a study published last week in Science Advances, the current extinction rate could be more than 100 times higher than normal—and that’s only taking into account the kinds of animals we know the most about. Earth’s oceans and forests host an untold number of species, many of which will probably disappear before we even get to know them. (See pictures of 10 of the earth's rarest animals.)
Journalist Elizabeth Kolbert’s book The Sixth Extinction won this year’s Pulitzer Prize for general non-fiction. We talked with her about what these new results might reveal for the future of life on this planet. Is there any chance we can put the brakes on this massive loss of life? Are humans destined to become casualties of our own environmental recklessness?
The new study that's generated so much conversation estimates that as many as three-quarters of animal species could be extinct within several human lifetimes, which sounds incredibly alarming.
Yes. That study is looking at very well-studied groups of animals. They restricted themselves to vertebrates—like mammals and birds and reptiles and amphibians—and said, OK, let’s look at what is actually happening. And they document pretty compellingly that extinction rates were already extremely elevated in [the year] 1500, and are just getting worse and worse.
They’re very high figures, and people are kind of getting inured to it. Kids who are born 10, 20 years ago—they’ve grown up their whole lives with these numbers. They don’t really think, OK, well that really is fantastically unusual. (Read about a study that says extinction rates are a thousand times higher because of humans.)
People have been debating whether we really are in the throes of a sixth mass extinction. What is your opinion?
To be honest, that’s one of those debates where I think we’re focusing on the wrong thing. By the time we have definitive answers to that question, it’s possible three-quarters of all species on Earth could be gone. We really don’t want to get to the point where we definitively can answer that question.
What is clear, and what is beyond dispute, is that we are living in a time of very, very elevated extinction rates, on the order that you would see in a mass extinction, though a mass extinction might take many thousands of years to play out.
Are there habitats or species—or groups of animals that you think are especially vulnerable to the changes that are going on?
Island populations are very vulnerable to extinctions for a couple of reasons. They tend to have been isolated. One of the things we’re doing is removing the barriers that used to keep island species isolated. New Zealand had no terrestrial mammals. Species that had evolved in the absence of such predators were incredibly vulnerable. A staggering number of bird species have already been lost on New Zealand, and a lot of those that remain are in deep trouble.
So, places that have been isolated for a long time. Those are very vulnerable. Species that have a very restricted range, that exist only in one spot in the world, those tend to be extremely vulnerable. They have nowhere to go and if their habitat is destroyed, say, then they’re gone.
The human component of this story—the fact that we appear to be responsible for the sixth extinction—what is some of the best evidence for our involvement?
I don’t think there’s any dispute that we are responsible for the elevated extinction rates we see now. There are very few, if any, extinctions that we know about in the last 100 years that would have taken place without human activity. I have never heard anyone argue, “oh extinction rates, that’s just a natural thing that would have happened with or without humans.” It’s just pretty much impossible to argue that.
If we’re pulling the trigger, what did we load the gun with?
There are thousands and thousands of scientific articles that have been written about this. We loaded it with simply hunting. We brought in invasive species. We are now changing the climate, very, very rapidly, by geological standards. We are changing the chemistry of all the oceans. We are changing the surface of the planet. We cut down forests, we plant mono-culture agriculture, which is not good for a lot of species. We’re overfishing. The list goes on and on.
There’s no shortage of bullets. We have a pretty big arsenal right now. (Read about which animals are likely
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