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Is Life on Earth Killing Us?

Encore broadcast that originally aired May 6, 2009


Is life toxic? Award-winning paleontologist Peter Ward thinks it is and has put forth a provocative theory about the unhealthy relationship between humans and other life forms and the planet in his new book The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?


Peter Ward, paleontologist and professor of biology at the University of Washington. He is author of the new book The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?

MAUREEN CAVANAUGH (Host): As politics and popular culture fully embrace efforts to go green and minimize human impact on the environment, another voice has entered the debate. It's not a voice that challenges global warming, or the power of humans to harm the environment. Rather, it challenges the very underpinnings of the environmental movement, the theory that left to its own devices nature is a self-regulating force that sustains life on this planet. Based on the record of mass extinctions in the deep history of Earth, paleontologist Peter Ward has put forth a theory that nature is not naturally good at sustaining itself, in fact, it can be very efficient at turning back on itself with extreme and lethal consequences. Ward has named his theory the Medea Hypothesis, after the Greek myth of a pitiless and vengeful woman who killed her own sons. Not exactly our typical image of Mother Nature. Peter Ward is an award winning paleontologist and professor of biology at the University of Washington. The full title of his new book is "">The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?" Peter, welcome to the show.

PETER WARD (Author): Thanks so much.

CAVANAUGH: Now I gave a brief overview of your theory but tell us more. What is the Medea Hypothesis?

WARD: Well, Medea was, as you mentioned, a very pitiless mother and I was trying to put up, I guess, an alternative to the long running Gaia Hypothesis. Gaia, named for the good mother, the Greek good mother of Earth, is an idea or a theory or a hypothesis, depending on who you talk to, that life really makes the planet better for life. That the longer life is on this planet, the better the recirculatory systems of elements, the temperature, the pH of the oceans, all of these get better and better and better, suitable for ever more life. And left to its own devices, we just get this more and more optimal world, and there are a lot of us who study deep time and also the far future so we've tried to merge the deep time geological record with what the astronomers can tell us really see a different picture. It's like nature is – certainly has no direction and it's a rather blunt, stupid instrument blundering from place to place. Even naming it Medea probably gives nature more credit than it's worth. But we do see this reversion to older times on occasion and these are called mass extinctions. Now we've all seen Bruce Willis try to save the Earth in "Deep Impact" and "Armageddon," but most of the mass extinctions weren't caused by asteroids from space as the movies would show us but rather microbial takeovers, times when oxygen has dropped. Really nasty poison-emitting bacteria begin to cover over the oceans and the subsequent emission, the very poisonous hydrogen sulfide gas, five times in Earth history, has almost ended life on this planet. So we don't see any traction at all and, in fact, the only out on this planet or any planet, because we think the same sort of manifestations will happen anywhere, is intelligence. Intelligence and engineering.

CAVANAUGH: Now I want to break this down a little bit because the Gaia Hypothesis that you referred to is the kind of thing that has really sort of given the modern environmental movement its basis, the idea that there are systems in place, nature puts systems in place that sustains life and then man comes along and disturbs those systems. Tell us why people believe in this hypothesis. What kind of systems are they referring to?

WARD: Well, the systems they do talk about mainly are the carbon cycle. As we know, carbon, which is the majority of the scaffolding of every one of our cells, is necessary to us all. And there's carbon dioxide in our atmosphere. Plants take that, turn it into oxygen as well as plant material. So without this plant cycle, cycling carbon in and out of the atmosphere, there's really no place, there's no ability to have animals on our planet nor is there oxygen which we animals all need. But on the other hand, if you look at the longterm history of carbon in the atmosphere, it's pretty interesting. It's been dropping in almost a straight line for the last 500 million years and we project forward and see when it hits zero. And it hits zero in about the same amount of time that we have had animals on this planet and the reason carbon is dropping is that animal life and plant life has been bundling up in rocks. Those rocks get out of the cycle, they get stashed away on continents, and the end of life as we know it is foreordained by life removing this carbon from the cycle. It's not inorganic, it's nothing to do with anything but life.

CAVANAUGH: I see. And so that is where you see that life turns on itself and basically brings about its own end.

WARD: Yeah, there's nothing conscious about it.


WARD: It's just that evolution has increasingly optimized the ability of certain types of life to make calcium carbonate skeletons. This requires CO2 and it's been sucking CO2 out of the atmosphere and it will be the self-limiting end of life on this planet.

CAVANAUGH: Now, Peter – Peter Ward, author of "The Medea Hypothesis," you told us – you kind of told us real quickly about some of the mass extinctions that have occurred on Earth. There have been five mass extinctions, is that correct?

WARD: Well, there was five big ones when over half the species go extinct and we paleontologists refer to those as the big five, but there's ten others that were also very catastrophic although not getting up to, say, the 50%. Of all of these mass extinctions, only one can be pinned on an asteroid impact and that's, of course, the famous dinosaur killing event. We found the crater. It is in the Chicxulub region of Yucatan Peninsula. And for a while, from, say, the year 1990 to even two years ago, we thought that every one of those mass extinctions was caused by impact but we have really sophisticated new ways of looking at rocks and we can extract molecules called biomarkers. These are the remains of cell walls, the various types of bacteria, and it's a brilliant case of microbes run wild in each of these mass extinction episodes and it's brought about first by short term global warming, second by an anoxic loss of oxygen out of very stagnant, cesspool oceans, and, thirdly, those conditions allow these poison brewing bacteria to step up and poison everything and they've done it fourteen times.

CAVANAUGH: Tell us a little bit about that cycle, that it's sort of like the reverse of life cycle that happens in the oceans when there's this overproduction of microbes and that robs the oceans of oxygen.

WARD: Yeah, the primary catalyst to all of this is extraordinary volcanism. For short periods of time, say even a half million years, the Earth spews out enormous, gigantic provinces of lava. It's not like one volcano like Mt. St. Helens. These are areas, the biggest, for instance, covers a huge area of Siberia almost the size of the continental U.S. So it's not the lava that kills things, it's the CO2, the carbon dioxide. The greenhouse gas that goes in the atmosphere. The planet warms to the point that if the poles are almost as warm as the equator there's nothing to drive ocean or air currents. When that happens, the oceans go stagnant. When they go stagnant, they lose their oxygen. When they lose their oxygen, the poison brewing bacteria take over. So it's – the volcanism or global warming starts the process but it's life that it causes the killing.

CAVANAUGH: I see. So – Well, this kind of leads to the question are we in the midst of another mass extinction by your calculations?

WARD: Absolutely. We are producing CO2 at a rate even faster than any of these past volcanic episodes. For instance, we know that there can never be sheet ice above about 1200 parts per million carbon dioxide. We're at 385 and climbing. And it may be that even at 1000 parts per million, which is someplace we will probably be certainly by 2200 but perhaps by 2150, so in a little over 100 years we may be at the same carbon dioxide level that created the conditions leading to these mass extinctions. So it's not anything that's going to happen five years after that. These are probably on millennial time scales. But then again, any species of mammal usually lasts 7 million years; we've been around a half million. Why can't we be a 7 million year animal? And if that's the case, we do have to worry about the next 1000 years, 2000, 5000 years, and this is staring us right in the face.

CAVANAUGH: All right. So it's interesting, your theory doesn't necessarily counter that of, let's say, let's call them traditional environmentalists who say that, you know, the Earth is in a bad place right now. But your tactics are different. It's not that people should stand back and let nature take its course, it's people have to do something.

WARD: Absolutely. The only way out is engineering. And by engineering, I don't necessarily mean bricks and mortar and great big metal scaffoldings. The engineering that we're going to be doing, and are doing, is going to be at the life level. People like Craig Venter are working furiously on trying to produce fuel out of microbes and food out of microbes. I was with Freeman Dyson this last weekend and his sense of things is the same thing, is that bioengineering is the engineering of the future. But there's a nastier possibility and Paul Crutzen, the Nobel Prize winning atmospheric chemist, has said if we don't get our act together, we'll have to seed or salt the atmosphere with sulfate minerals. This is what a volcano does. This will certainly reduce warming on the planet but at the same time it'll cut down crops and it'll further acidify the ocean. This is a draconian solution that we should never have to get into.

CAVANAUGH: Right now, Tyler is on the line from San Marcos. Good morning, Tyler.

TYLER (Caller, San Marcos): How you doing?


TYLER: I just wanted to say I thought it was pretty interesting that you're essentially saying, you know, the cycle of life on Earth is self-destructing in a way but renewing in a sense as well. And I find it interesting because we've heard a lot over the last few years that black holes essentially that are forming are slowly sucking in planets and giving birth to new galaxies and essentially that whole circle of life is starting over again on a much larger scale. So, good stuff.

WARD: Well, thanks so much.

CAVANAUGH: And actually you did publish a book back in 2000 called "Rare Earth: Why Complex Life is Uncommon in the Universe." So you're basically trying to find universal principles in the way that the Earth – the Earth has mass extinctions and then comes – the life comes back.

WARD: Absolutely. I'm a part of the University of Washington Astrobiology Group and it's a larger part of NASA. We're part of the NASA Astrobiology Institute. And what we're trying to do are just understand principles from Earth that apply to other planets. You know, we're finding these fabulous Earth-like planets everywhere now that we're starting to look. And the Kepler Mission is now flying. We can expect to really understand that we are not alone as an Earth-like planet. On the other hand, any planet has a series of catastrophes it probably goes through. I think the lesson that we have is the only out, the only way to extend the length of the biosphere is intelligence, just like the only way we can keep ourselves alive a lot longer than we normally would is through medicine, exercise, diet. I mean, it's exactly equivalent, what we have to do to our planet.

CAVANAUGH: I'm speaking with Peter Ward. He is the author of "The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?" And, Peter, you mentioned speaking – having – speaking to other scientists in related fields about this, how, in general, have scientists reacted to this Medea Hypothesis?

WARD: Well, it kind of goes along lines of who does and who doesn't believe that the greenhouse gases cause global warming. As you probably know, the vast majority of people do understand that carbon dioxide is a very potent greenhouse gas and yet there are still skeptics. And some of the skeptics say, no, greenhouse gases have nothing to do with it, that it's entirely cycles of the sun. And yet deep time really does show us. We can see from the rock record what past carbon dioxide levels were and we can also detect relative temperatures, were they high, were they low on the planet from geological evidence. There's really a tremendous correspondence between high CO2, no ice caps or ice sheets, and very high global temperatures. And so you would have to just invoke the most amazing coincidences to be able to say that it was every single time the sun and just by coincidence we had high CO2. So it's not as if I'm running into a lot of opposition because much of what we're talking about in this book deals with climate cycles.

CAVANAUGH: Let's take another call. Kumar is in Sorrento Mesa. And good morning, Kumar.

KUMAR (Caller, Sorrento Mesa): Good morning. Thanks for taking my call.

CAVANAUGH: You're welcome.

KUMAR: There seems to be two views here on these things we have been hearing that, you know, we've been pumping so much CO2 into air and we have to control that and try to make things better. Now there seems to be another perspective now that, you know, even if we don't do anything, nature itself has to be protected from the Earth. So how does that, in your perspective, change the green movement that we're in right now? Should it modify it? Should it be enhanced? Or, you know, we don't have to worry about it?

CAVANAUGH: Okay, Kumar, I – I – What does this do to everybody going green?

WARD: Yeah, great question. The irony of all this is the greatest danger to the long term survival in life on Earth is not enough carbon dioxide. The greatest danger to the short term human society is too much carbon dioxide. What a mess. I mean, way off in the future, we're going to look back and say, wow, I wish we had some of that CO2 that we burnt up in all that coal oil because way down the line, we're going to have to extract it from rocks. In the short term, the greatest single threat facing our society is sea level rise. I have a next book coming out in about six months or a year, are – it's about the rise of sea level, what it's going to do, what it's going to do to the Imperial Valley, to the great valley of California, what it's going to do to crops. We've got to get through this next two or three centuries. We've got to be able to engineer the atmosphere so that it allows us to keep ice sheets, Greenland ice sheets, Antarctic ice sheets. I just came back from Antarctica. I was six weeks sitting on a melting ice sheet. It's spectacular what's happening down there and very, very scary.

CAVANAUGH: And as you said before in your study of deep time, you've seen what happens when the Earth loses its ice caps, right?

WARD: Yes, we have 240 feet of sea level rise facing us if we lose the west Antarctic ice sheet. If we lose the other Antarctic ice sheets and if we lose the Greenland ice sheets – Again, an ice sheet is something that sits on continental rock. An ice cap floats on the ocean, if they melt away, there's no effect on sea level. But the ice sheets, when they melt, have a drastic and quick effect on sea level.

CAVANAUGH: I see. We have another caller. Jack is in Encinitas. Good morning, Jack.

JACK (Caller, Encinitas): Yes, hi. The way I've understood the Gaia principle is it doesn't have too much attached to it other than the concept that the Earth is a living entity and in so it being a living entity, all these dynamics that you're talking about are possible.

WARD: That's a great question. Actually, there are several flavors or varieties of Gaia. That's the strongest Gaia in the sense that Earth is alive is the brand that is the most extreme. James Lovelock and Lynn Margulis are the two who really codified Gaia, have now backed way away from that. What they support is something called optimizing Gaia where the systems produced by life and run by life optimize for the future life. But we try to – at least the Medea Hypothesis really tries to test that and we can predict that there will be a shortening of the biosphere because of the loss of CO2 that runs life because of life, and this is very anti-Gaian.

CAVANAUGH: Right. Now I'm wondering, I don't know if we've ever really mentioned this, that Gaia, the Gaia Theory's named after the Greek myth of a nurturing mother, a mother that tends well to the life that she gives whereas, of course Medea is the one who kills life that she gives. I wonder if it's possible that both the Gaia and Medea theories are partially true, that sometimes nature does actually develop self-sustaining systems and then sometimes chaos rules.

WARD: Well, you know, that's absolutely right. I'm not saying – standing up here saying I have a total replacement because there's been a tremendous scientific advance coming out of Gaia. A whole field of science called Earth systems science has arisen. But on the other hand, there's never been a viable alternative to Gaia. It's as if it sits there, doesn't have to be tested, the only game in town. And as we all know, competition sharpens everybody's game and so I'm putting a new player into this whole game here.

CAVANAUGH: Let's take another call. Andrew's in Pacific Beach. Good morning, Andrew.

ANDREW (Caller, Pacific Beach): Hi. Thanks for taking my call.


ANDREW: I'm wondering whether or not sort of making an analogy with parasites, successful parasites, don’t kill their hosts, meaning they – because if they kill their host, they die. And the analogy being if we, who depend on the Earth and its systems, are going to be successful, we can't kill those systems. And whether there's any, you know, value that can be gained from a systems level looking at those, how parasites are successful.

CAVANAUGH: Well, thank you for that, Andrew. What do you think, Peter?

WARD: Well, that's a great analogy. Good parasites don't kill but, unfortunately, evolution takes a long time and early in the evolutionary history of any parasite, they stupidly do kill. It takes a long time to finally codify within your DNA methods to extract as much blood as possible from that host and not kill it. On the other hand, we are competing with other life forms on this planet and while we may really want to do the best we can to keep the planet good for us, other organisms, including vast fleets of microbes, would rather there be no oxygen, would rather that we have a very hot instead of a cool world. They're not doing it consciously but we are competing again. And we humans, if we want to go in for the long term, we’re going to have to engineer this planet for our comfort, and we will have to do it through engineering.

CAVANAUGH: Right. I want to ask you, in the minutes we have left, about this engineering solution that you suggest. And I'm wondering, in terms of trying to slow the rise of the oceans, what kind of an engineering solution might there be?

WARD: Well, there's several of these. We – The easiest engineering solution is for us to engineer hybrids and engineer cars but especially for us to back away from this profligate burning of greenhouse gases. Chinese alone, the Indian and Chinese car factories, which are just coming online, it's not the cars that are the problem, it's the power plants needed to build the steel, melt the metal, to produce the cars. And these are all coal-fired. So we've got these huge numbers of coal-fire plants that are going to continue over the next century if we keep going as we're going to be putting greenhouse gases up. Our first engineering is to stop putting CO2 in the atmosphere and try to maintain sea level at a point where we don't need to relocate our major cities, that we don't need to relocate most of our farms. And when you think of vertical sea level rise, a meter up, three feet up, doesn't sound so much but think about this. Every three feet up causes many more feet laterally of salt moving sideways. And that salt, once it gets into the San Joaquin Valley, as it already is, can totally negate any agriculture from the San Joaquin.

CAVANAUGH: Do you think that we have a chance of stopping that?

WARD: Well, there's certainly the cautiousness we all see over the last five years, five years ago how often did you hear about global warming to the extent that you do now?


WARD: People are waking up. The other hand, the last year has seen the greatest amount of information about global warming ever and the new figures for this year just finished came in. There's been no reduction. It's 2.1% increase in CO2, 2.1 parts per million, actually. This is terrible. I mean, this means we've given it a good shot for the last year, and there's been no reduction.

CAVANAUGH: Well, even since your coming at the whole environmental cause in perhaps another direction entirely, there's a lot about your theory that environmentalists seem to be able to get behind.

WARD: Well, I hope so. I mean, in this particular case that one of the engineering solutions probably should be engineering a way that there's not so many more humans in the future. And that's certainly more than engineering, as you know. That's going to have to be a social movement. But we are at six-point-something billion, we're heading towards 9 billion. There's a three foot sea level rise already built into the system of the oceans; we can't stop it. A three-foot sea level rise intersecting a 9 to 11 billion population where we're covering over a large percentage of the near sea level farmlands and croplands, spells disaster.

CAVANAUGH: The name of the book is "The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive." And, Peter Ward, I want to thank you so much for talking with us.

WARD: Thanks for the great and very intelligent questions from you and your listeners.

CAVANAUGH: Thank you so much.

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