The Conversation: Elizabeth Kolbert and Bill McKibben

Five great extinctions have occurred in the history of Earth. Now, in The Sixth Extinction: An Unnatural History, journalist Elizabeth Kolbert eulogizes the decline of a handful of species and makes the case that a new mass die-off is under way. Industrial processes that pump carbon dioxide into the ocean are making life untenable for the thousands of plants and creatures that live in its depths, especially the vast but fragile coral reefs. Whole populations of bats in the northeastern United States have been decimated by a fungus brought to New England by an unsuspecting European traveler. The great auk, an extinct bird, suffered its last stand on an Icelandic island after being relentlessly hunted for just a few decades.

By the end of the 21st century, scientists estimate that half of the world’s biodiversity will be gone. This extermination, which has the potential to be the most cataclysmic, is almost entirely driven by humans. The beginning of the sixth extinction coincided with the first traces of human life—we caused it, and we may fall victim to it as well.

Bill McKibben, a writer and the founder of, a global organizing effort to curb the advance of climate change, has argued for more than 20 years that we are approaching an environmental point of no return. In a series of best-selling books, McKibben has warned that if humanity is to survive, we must recognize that climate change is gradually making the planet uninhabitable.

In this installment of “The Conversation,” a new Prospect feature, Kolbert and McKibben discuss the scope of the sixth extinction and grapple with why raising awareness about environmental catastrophe is so difficult. Their exchange has been edited for concision and clarity. —Amelia Thomson-Deveaux

Nicholas Whitman,

Elizabeth Kolbert (left) and Bill McKibben

Bill McKibben: Of all the things I found to be haunting in the book, the one that most stood out to me was your description of walking out along the Great Barrier Reef in the darkness. What did it feel like?

Elizabeth Kolbert: That was an amazing experience, which is ironic—in reporting a book that’s just chock-full of bad news about the world, I got to go to the most spectacular, unspoiled places on the planet. One of these, as you mentioned, was a tiny island on the edge of the Great Barrier Reef. I was on this island because a team was doing research there on ocean acidification. They had a buoy out on the reef flat, where they’d collect samples. When you are out there at night and there is no horizon, there is nothing but blackness and amazing stars and your flashlight. There are animals lurking in these pools waiting for the tide to come back in so they can swim out. Enormous turtles, octopuses, these giant clams that leer at you with lurid, vividly colored lips.

McKibben: That’s such foreign fauna, especially for those of us who live in the mountains in the eastern United States. Did you have a sort of Jacques Cousteau reaction—“I love everything around me”—or is your appreciation of this kind of biodiversity more intellectual?

Kolbert: I think the alienness of that underwater world prevents us from appreciating what we are doing to the oceans, which is in some ways even more serious than what we are doing to the land. By pouring carbon dioxide into the ocean, we are doing something that may never have happened before. It has no analogue in the geological record because we are doing it so fast, acidifying the water at such an extreme rate. But we are very much land creatures, so we don’t appreciate this amazing underwater realm, and we’re not aware of what we’re doing to it.

McKibben: You were one of the first people outside the world of science to understand the full implications of ocean acidification. Do you think of us as living on a kind of ocean planet now? 

Kolbert: It’s difficult to exaggerate the significance of the oceans. If you have ever brought home a piece of coral from a trip to the Caribbean, you can imagine that if you put that in a jar of vinegar, it would dissolve. That’s an extreme example, because vinegar is very acidic, but you can imagine that long before you get to the point where coral dissolves, it becomes difficult for the coral to do its job. We are making it hard for these organisms to do what they are evolutionarily programmed to do and have been doing for hundreds of millions of years.

McKibben: The hallmark of evolutionary biology is adaptability. Is the main thing that’s different in this era the speed with which we are forcing things to adapt? Is that the single biggest new variable in this new system?

Kolbert: I once got this question from a person who said, “Well, if things start going extinct, won’t new things just evolve?” It was like extinction and evolution were a one-for-one trade. But the answer is that you can drive things extinct quickly, but it is very difficult to speed up evolution. If we were driving these changes at a pace that’s hundreds, even a million times slower, then yes, maybe most things would adapt to that, and we would get a very different world but not necessarily a humongous wave of extinctions. But otherwise you can do the math yourself.

McKibben: And in this case, we are talking about an equation where we’re not even close. It’s not like we are going twice as fast as species can adapt—we are going tens of thousands of times faster.

Kolbert: There have been moments in the past where the earth has experienced very swift, extreme changes—in a geological sense. And right now, we are in one of those moments. We are causing changes so fast that in the span of a human lifetime or a couple of human lifetimes, you can watch them happening. So part of the question for who will survive and who won’t is how fast generations are produced. If you are a microbe, you might do a lot better than an insect, which may do a lot better than a mammal. Big mammals are in serious trouble.

McKibben: In Vermont where I live, we are watching the moose, which are my favorites of all the northern mammals, being decimated.

Kolbert: Why is that?

McKibben: The single biggest problem is temperature change. Moose don’t like heat to begin with—any time it gets above 20 degrees, they’ll be looking for shade. But now ticks can live through the winter. So while any given moose generally would have 7,000 or 8,000 ticks on it, now they are finding them with 100,000 ticks. And they just can’t deal with it. The number of moose dropped by 50 percent in five years across much of the northern part of North America.

Kolbert: You also live near the epicenter of what’s happening to bats. Someone—almost certainly inadvertently—brought over a fungus that is killing off the little brown bat. One of the most ubiquitous animals in the Northeast is now listed as an endangered species in Vermont.

I visited a cave that used to be the biggest bat hibernaculum in the Northeast, with hundreds of thousands of bats. It’s now almost completely empty. One year I visited, and there were dead bats all over the ground, you couldn’t walk without stepping on them, and now it’s just this black, rich muck, which is their decomposed bodies, and these tiny little toothpick-like bones everywhere, a carpet of these bones. That’s what’s left of this incredible bat population.

McKibben: It doesn’t sound like adaptation is going to happen in the time frame we have.

Kolbert: What’s happening with the little brown bat is a case where we accidentally brought together these evolutionary lineages that have been separated for a long time, with disastrous results. Often we bring new species together and they coexist, they muddle along, but if we keep doing it over and over again, then sometimes the consequences will be bad.

McKibben: Another thing that is amazing to me is to watch things that we utterly depend on just stop working. Corn won’t tassel. It won’t set seed if it’s 95 degrees outside. It’s even affecting us. There’s a new study that says the human ability to perform outdoor work has already dropped 10 percent due to an increase in heat and humidity. It’ll be 20 percent by midcentury.

Kolbert: Different organisms have different physiological heat tolerance. One scientist whom I talked with who’s studying climate change explains that all of these species near the equator are on the move—they’re going upslope, toward the poles. But in the Amazon lowlands, where the temperatures are consistently among the highest on Earth, what’s going to move in there? We’re radically changing what is now the most biodiverse part of the world.

McKibben: But on the other hand, there are things that do extraordinarily well in the simplified world that we’re creating.

Kolbert: Wherever you have sunlight and nutrients, something will be able to survive. There’s a lot of versatility, but it won’t be what was there before, and that will have an effect of its own. Some things will do really well and some things may surprise us. We’re in uncharted territory, but we seem hell-bent on finding out what a simplified world will look like. And that’s a question I’ve got for you—what does motivate us to take action, to reverse this process as best we can? What gets people to make that step?

McKibben: That’s an interesting question to think about in terms of evolutionary biology. One would think that if our big brain were equipped to get us into this kind of trouble, it would come up with something to get us out of it.

Kolbert: But evolution is such a random process—it probably didn’t work that way.

McKibben: OK, so the hope is not that the brain is going to get us out of this mess but that maybe the human heart can. We have to hope that there is something in our culture that evolved, not biologically but culturally over time, that lets us have enough concern and compassion for the rest of creation, for things deep into the future, generations to come. But although there are lots of people engaged, there are also a very few fighting to maintain the current system as it is, who have so much money that their small numbers are offset by the size of their wallets. When you were reporting this, how did you manage to keep any sort of equanimity? You’re basically describing an impending apocalypse. What is the proper state of mind in which to contemplate an apocalypse?

Kolbert: I get asked that question all the time, and my answer is always that I don’t have a good answer. For the people involved in this research, in some ways this is a fascinating and exciting time. You’re watching natural phenomena that we should not be able to watch. But many of them are despairing. Someone told me about a party for a famous conservation biologist where they gave out party favors—things they use in the field like duct tape, rope, a bottle of rum—and someone suggested that they also give out a razor blade to slit their wrists because everything that’s happening in conservation biology is so depressing. People have already asked me what the hopeful part of my book will be, and my only answer is that it’s not there.

McKibben: What I keep finding is that these twin problems—climate change and ocean acidification—are so huge that people feel a lack of agency. They think to themselves, it’s too big, there’s nothing I can do about it, which is certainly true in an individual sense. We have been getting unremittingly bad news for 25 years, and it keeps getting worse than the scientists thought it was going to be. Have you found that scientists in this realm—who have generally been quite conservative in their estimates and unwilling to speak out much—are so shocked by what they are seeing that they’re becoming more aggressive about letting people know?

Kolbert: If you read the scientific literature, there is relentless talk about the “current mass extinction.” We have sophisticated ways of looking back through geological history and trying to tease out what the planet was like hundreds of millions of years ago, and in that context, in that sweep of history, what we are doing is so unusual. It becomes more unusual the further back you look. And if we continue on our merry path, we are going to create a level of ocean acidification that probably has not been witnessed on this earth for hundreds of millions of years.

McKibben: It’s a pretty remarkable thing to have done in a few dozen years and on a small portion of the globe.

Kolbert: It’s remarkable for having been unintentional. But now we do know what the consequences of our literally earth-changing actions have been. That is the burden of our time, that burden of knowledge. So what do we do with that?

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