Courtesy: Henry Holt and Co.


Somewhere around 200,000 years ago, a new primate emerges on Earth.

“The members of the species are not particularly swift or strong or fertile,” the New Yorker’s Elizabeth Kolbert writes in her new book, “The Sixth Extinction: An Unnatural History.” “They are, however, singularly resourceful.”

It is, of course, us — big-brained, small-browed genetic mutants clever enough to outcompete animals ten times our size and gradually fan out across the globe.


Eventually, humankind invents axes, engines, cities and strip malls. We tear down forests and dig up fuel from the ground.

Other times we excavate out of curiosity, traveling backward in time through the records of bones, fossils and rocks that eventually give up clues to mass tragedies in the ancient past. Huge portions of the world’s creatures disappeared in a geologic blink of the eye.

In fact, five blinks — so far. The reasons aren’t always settled in science, but strong possibilities for the various mass extinctions include a dramatic release of carbon dioxide in the atmosphere, climatic shifts that tipped the globe into prolonged ice ages and a gigantic asteroid strike that kicked up enormous clouds of dust.

The early part of Kolbert’s new book is an exploration of this exploration of the past, telling the stories of scientists who worked to reconstruct this grim timeline of species loss. But mostly it’s scene setting for the real subject of the book, the one telegraphed in the title: The Sixth Extinction.

The salient characteristics of the latest epoch are that we appear to be living through it now — and causing it.

We’re directly destroying the habitat of millions of species as we encroach upon ever more wilderness. And humankind is fundamentally altering their natural surroundings through climate change, as the greenhouse gases from that energy in the ground makes oceans more acidic, rain forests hotter and desserts even drier, among much else.

About 10,000 species disappear from the planet each year, which is 1,000 to 10,000 times greater than the “natural extinction rate,” according to the World Wildlife Fund. The U.N. Intergovernmental Panel on Climate Change report in 2007 predicts that an increase of  3.5 degrees Celsius could wipe out 40 to 70 percent of the species assessed so far.

If carbon dioxide levels continue to climb, some models forecast as much as a 6.4 degree Celsius increase by the end of the century. That’s 11.5 degrees Fahrenheit.

“Right now, in the amazing moment that to us counts as the present, we are deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed,” writes Kolbert, author of the alarming 2006 book on climate change, “Field Notes From a Catastrophe.” “No other creature has ever managed this, and it will, unfortunately, be our most enduring legacy.”

It’s difficult to decide whether Kolbert’s convincing argument that homo sapiens are the cause of the latest mass extinction is, on balance, more demoralizing or empowering.

As the lack of any significant policy shifts on these issues underscores, climate change and deforestation are perfect examples of the tragedy of the commons. It’s in everyone’s long-term collective interest and almost no one’s immediate self interest to stop.

But if humans are the cause, it also means we, by definition, have the power to alter the outcome — more so, at least, than in the case of a six-mile wide asteroid barreling down on Earth.

“It’s an incredibly fascinating and horrifying situation we’re in. We’re this amazingly advanced, scientifically sophisticated civilization, and we have information that’s telling us that what we’re doing is very bad for us — and we keep doing it.” — Elizabeth Kolbert

Humans are, let us recall, “singularly resourceful.” Our brains are large enough to stop ignoring established science, elect leaders willing to act, dream up more sustainable means of fueling the modern world — and perhaps invent methods to mitigate the damage already done.

This being a tech publication, I focused on the latter two subjects during an interview with Kolbert last week.

She said the grave challenges before us probably can’t be solved without technical advances, specifically in the development of more efficient clean energy. But she’s dubious about the wisdom of some proposals in the realm of de-extinction and geoengineering, and stresses that the problems can’t be solved through technology alone.

The interview that follows has been edited for length and clarity.

Elizabeth Kolbert, author of "The Sixth Extinction: An Unnatural History"

Barry Goldstein / Courtesy: Henry Holt Elizabeth Kolbert, author of “The Sixth Extinction: An Unnatural History”

Re/code: When I read “Field Notes From a Catastrophe,” which came out eight years ago, I felt like it was a call to action on climate change. This book felt more like you were describing an inevitability, like vast numbers of species are as good as gone. Am I just inserting some of my own pessimism into it, or is that an accurate read of your feelings on the issue? 

Kolbert: Climate change is a pretty clear threat to human society and there are a lot of things that we could do to minimize that threat. We’re not doing them, but we could do them.

They would probably be quite useful for human society. They wouldn’t all necessarily have the same beneficial results for the rest of the species on the planet. It would really depend on a lot of other different things.

I don’t think you’re misreading either book, but I think that the difference is, are we talking about what we should be doing to improve our own situation — humanity’s situation — or what we should be doing for the other species on the plant?

Now reducing greenhouse gas emissions would have a very, very ameliorative effect for a lot of other species, but it would not solve a lot of problems confronting species.

If we came up with some great carbon free source of energy — fusion or something let’s say — it would really depend what we then did with that energy. If we used it to continue cutting down the rainforest, it wouldn’t help other species.

There are many efforts underway to save individual species, some of them, as both your and Jon Mooallem’s recent book “Wild Ones” point out, seem pretty difficult to implement on a broad scale. Are there some more fundamental, structural changes we could undertake to save a significant number of species at this point?

What conservation biologists would tell you is that, given all the changes we’ve set in motion in the world, the best thing we could probably be doing is to set aside big tracts of land. And then we would have to connect these tracts so all these species — which are on the move already, millions of them, because of climate change — have some place to go.

E.O. Wilson laid this out in his book (“The Future of Life”), he’s a big and elegant proponent.

That will not prevent extinction, but that would be our best hope for letting those species that can make it through these changes — and there’s a lot of warming already in the pipeline — make the transition.

So that’s probably what we should be doing. I have yet to hear a better solution than that. But it’s a lot easier said than done.

You mentioned the Frozen Zoo in San Diego in the last chapter, where they’re storing cell lines of endangered and extinct animals, and there are also efforts underway to bring extinct species back like the passenger pigeon through genetic engineering. I’m curious about your thoughts on these technological approaches to repopulation or de-extinction?

I just wrote a piece in which I responded or commented on the Times Magazine piece, which is a really interesting article. But I think if you really look at it in any kind of rigorous way — and a lot of people in the piece commented on this, including the head of the lab, the guy trying to resurrect the passenger pigeon — as you look at what’s involved here, we are so far from being able to do this.

You could theoretically recreate a Neanderthal too, but even if you have the genome, you don’t have the animal. An animal is more than a genome, you are more than your genome, human society  is more than the sum of all our genomes. So what are we talking about and why are we doing this?

It’s not going to be possible in the case of the passenger pigeon to bring back a flock of a billion strong, or even a couple hundred.

So what do you have? You have some curiosity that has to be kept in a zoo. I’m pretty down on the idea. I think it’s basically being done for people, not for other species or for the planet. It’s being done because we think it’s cool or it assuages our guilt.

I wonder about how useful it is to bring back a species into the same habitat that already killed it off once. 

Exactly. With the passenger pigeon you could argue, actually, a lot of the forests in the Northeast are in better shape than when the passenger pigeon died off. That’s quite possibly true.

But many people have speculated that the reason they went extinct —  one of the contributing factors was obviously the slaughter — but also because they needed these huge flocks to survive, there’s something in their mating habits. That’s why even though there were small flocks in captivity toward the end, they didn’t reproduce and we don’t have any passenger pigeons today.

But I think you make a good point. Certainly take the Sumatran rhino, which is down to about 100 individuals. Some of that is poaching, but a lot of it is habitat loss. The forests of Indonesia and Malaysia have just been mowed down. So where are you going to put them even if you could get them?

You also touch on geoengineering in that chapter, and you spent a lot of time with Ken Caldeira who in addition to his ocean acidification work, did some of the first serious modeling of the feasibility of cooling the earth by injecting sulfur dioxide into the stratosphere. What do you make of geoenginnering options — and I know that’s a wide spectrum — as potential weapons in our arsenal for combating climate change?

I’ve talked to Ken about this and he’d be the first to say: “Geoengineering might be something that helps get society through a really potentially bad patch, but it has a lot of complexities.”

It’s really clear the benefits are very uneven. There are real questions about rainfall patterns and things like that. Even if it were practically possible, which I’m going to pass over for the moment.

A scheme where we’re shooting sulfates into the stratosphere, that doesn’t deal with ocean acidification. It just makes it worse and worse.

And once you get into a situation with geoengineering, it commits you. If you were to geoengineer using sulfates and then you stopped, you’d get this fantastic and very fast run up in temperatures. So you’re committing yourself forever. And if you were also at the same time increasing the Co2 concentration in the atmosphere, then you’re committing yourself to more and more sulfate, because they have to balance out.

Paul Crutzen (who shared the Nobel Prize in 1996 for work on the “formation and decomposition of ozone”)  wrote a paper saying we may have to consider this, because we’re not doing anything else and we’re going to be so thoroughly screwed.

But it’s not something I’d recommend. I don’t think it’s the path most likely to lead to a happy outcome for people or anything else.

What ways can technology be brought to bear on these issues?

The search for a carbon-free source of energy. If you could get a breakthrough in the efficiency for solar panels, for instance, you could make a serious difference in our energy consumption and bring the cost down. Everyone could have solar panels as opposed to burning coal to make electricity.

If it became so cheap and so easy and so effective that the developing world didn’t take the development path that we did — skipping fossil fuels and going straight to clean energy — that would make a big difference. Energy technology plays potentially a huge role in ameliorating this situation.

But I don’t believe technology without thought and policy and conscious effort is going to solve all our problems. I believe, unfortunately, we’re going to have to exercise thinking and lot of self restraint and cooperation to really make a significant difference.

How much more optimistic or pessimistic are you, since the publication of “Field Notes From a Catastrophe,” that humankind will address the problem of climate change?

If you’re not more pessimistic you haven’t been paying attention to the events of the last decade. I really started to write that book basically a decade ago. At that point, scientists were saying we’re just seeing now the signal of climate change emerging from the noise. It was right at this point where the American Geophysical Union came out and said, “climate change is real and it’s happening now.” And one group after another of eminent scientists came out and said, “this is real, this is serious, we need to do something.”

But you know as well as I do that nothing has happened since then. The Obama Administration has made some laudable efforts to use regulatory power and those are not insignificant. But the basic situation has not changed. We’re still having moronic debates over the geophysics of climate change, which were actually settled over a hundred years ago.

So it’s hard to see the lack of a Kyoto Protocol, the failure of Copenhagen and the upward trajectory of emissions and come away saying, “I’m more optimistic.”

So what did you hope to accomplish with the book, do you hold out some hope that humans will wake up to the unfolding tragedy here and make more fundamental changes? 

It’s important for people to know what’s going on and to have the tools to make informed choices and to take responsibility.

Part of it is, I don’t think we should be able to say we didn’t know, because there’s a lot of information out there that scientists have that seems to me needs to get to the general public. That was really the impetus for writing the book.

It’s not that I have a solution I’m trying to work toward and just haven’t said what it is. I don’t have a solution. It’s possible that massive thinking and massive effort will yield, not a solution, but a much better future than the one we seem to be heading toward.

Sherwood Rowland, one of the scientists who discovered ozone depleting chemicals and who recently died, had a couple of great lines, including one I quoted in the book. “The work is going well, but it looks like it might be the end of the world.”

Another was, and I’m paraphrasing, “What’s the use of having predictive science if you don’t listen to the predictions?”

(The full quote goes: “What’s the use of having developed a science well enough to make predictions if, in the end, all we’re willing to do is stand around and wait for them to come true?”)

It’s an incredibly fascinating and horrifying situation we’re in. We’re this amazingly advanced, scientifically sophisticated civilization, and we have information that’s telling us that what we’re doing is very bad for us — and we keep doing it.


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