Science Talk

Are We Pushing Earth's Environmental Tipping Points?

Jon Foley, director of the University of Minnesota's Institute on the Environment, talks with podcast host Steve Mirsky about his article in the April issue of Scientific American, "Boundaries for a Healthy Planet". Plus, we'll test your knowledge about some recent science in the news. Web sites related to this episode include

Jon Foley, director of the University of Minnesota's Institute on the Environment, talks with podcast host Steve Mirsky (pictured) about his article in the April issue of Scientific American, "Boundaries for a Healthy Planet". Plus, we'll test your knowledge about some recent science in the news. Web sites related to this episode include

Podcast Transcription

Welcome to Science Talk, the more or less weekly podcast of Scientific American hosted on March 19th, 2010. I am Steve Mirsky. A team of 30 scientists from across the globe has put together a list of nine environmental processes that must remain within specific limits they say, or what they call "the safe operating space within which humankind can exist on Earth" will cease to be safe. Jon Foley, director of the University of Minnesota's Institute on the Environment and one of the group's leaders has an article on that effort in the April issue of Scientific American. We talked when we were both at the annual meeting of the American Association for the Advancement of Science in February in San Diego.

Steve:          You have this article leading off a section in the magazine and the way you approach things is through a discussion of tipping points. Let's go through them, and what do you mean by them and what the import of them is.

Foley:          Well, the idea of the article is about planetary boundaries, which is kind of a fancy way of saying two things. One is that we are approaching some limits in how our environment works that are like tipping points, they are like a cliff that you walk over and you can't come back again. Those things [are] sometimes very bad. We do not want to jump off cliffs without seeing where they are. But the other kinds of limits we are talking about are where you don't fall off a cliff, [but] you can't go back again. You suddenly end up in a one-way street, where you degraded something in the environment so much. It is effectively irreversible. You may not be off the cliff but you aren't ever going to go back to where you were before. So, this [broader] notion of planetary boundaries is something that a group of scientists around the world, led by Stockholm University and others, who had [recently] been pulling together to say, "Wait a minute. We are pushing the limits on climate change and biodiversity and land use and overdrafting water supplies and pollution levels and so on." and we thought well wait a minute, instead of adjusting all these issues independently, we need to make a map of the world, kind of showing where the edges are. You know, where the dragons on the map may be lurking if you will and that's really …

Steve:          So [that's a] reference to, maybe some of the younger people don't know.

Foley:          (laughs) Well.

Steve:          Those of us who are 400 or 500 years old like yourself know that on the old maps, where there will be boundaries, you would say …

Foley:          There will be dragons, you know, yeah.

Steve:          Right.

Foley:          Yeah, because we felt that is a [fun] metaphor because in those days, you know, we thought the world had an edge you could fall off of, and so we are kind of taking that metaphor maybe to [a] 21st-century equivalent, and we're saying, "Well, you aren't going to fall off the planet's gravity, but we may tilt our planet into a world we would never recognize, something that is so fundamentally different," and we've [kind of] fallen off the edge of the map in a sense because we can't make that world back again and we are very dangerously close to doing that.

Steve:          One of the points you make in the article is just how much of the photosynthesis that is carried on now, human beings kind of take advantage of, and it's an astounding percentage of all the photosynthesis in the world.

Foley:          Well, absolutely. There is no doubt that we live on a completely human-dominated planet. We use 40 percent of the earth's land right now in crops or agriculture. We use a lot of the world's oceans for harvesting fish and so on. And so, yeah, if we look at the photosynthesis, we are using like 30 percent to 50 percent of it depending on what numbers you look at.

Steve:          That is not 40 percent of the arable land that is 40 percent of all land.

Foley:          Yeah, all the land, everything.

Steve:          Is going into feeding ourselves.

Foley:          Yeah, yeah.

Steve:          Or feeding the animals that we then used to

Foley:          Most of it is actually for animals, yeah. It is exactly 40 percent of all of the land on earth, not counting Antarctica. But every piece of land, 40 percent of that, is already being used in one kind of agriculture or another right now.

Steve:          What are some of the other, let's talk specific[s on] some of the other tipping points that we're getting perhaps close to.

Foley:          Right. Well, the first that people are most familiar with I think is climate change. Now, yeah, there['s] some skeptics kind of on the edge of all [that] kind of stuff and there are reasons to be, you know, careful with the numbers we are using here of course. But the point is we are altering our climate; there is no way around it. The laws of physics demand that when we add greenhouse gases to the atmosphere, we are warming the planet. You can argue how quickly, how much, what it is going to do. But you can't reinvent the laws of physics. W[hat] we are finding though is that if we get to warming that is more than; right now, we warmed about, maybe six-tenths of a degree centigrade, about  [one] degree Fahrenheit warmer than we would have been. Well, that is not that much; we are beginning to see the effects where we get to be 2 or 3 degrees warmer than we have been for the last 10,000 years. That is where we started to worry about irreversible damage. Things are really bad like losing ice sheets, starting to raise sea levels, where coastlines have to be redrawn and people have to move. That is an irreversible nasty large impact you don't want. So, we think, that is a boundary we don't want to cross. We are going to have some more global warming but how much more and when this will become dangerous and irreversible is where we try to set a boundary. That's the most well known one. Another is the biodiversity loss. We are now losing species at [a hundred] to a [thousand] times faster then we should be based on the normal geologic rate of evolution in the loss of species; [a] thousand times faster. That is undermining ecosystems all over the world. We are losing critical species; think of those honeybees and you know, what is going on with them. This shows how dependent we are and that is where our ecosystem[s] are unraveling, too. Another big limit is pollution levels, especially from nitrogen and phosphorus, things that are in small amounts are very good for us, because they help fertilize our crops, but when we pollute too much more or use too much fertilizer, we can impair lakes and rivers and even degrade entire seas and coastal oceans, causing [them] to have dead zones where no fish can survive, like we have in the Gulf of Mexico.

Steve:          And have some kind of other, for example, in the Everglades [you have] cattails that move [in] and displace the native plant species and they ruin their habitat.

Foley:          [An invasive] species.

Steve:          The habitat right.

Foley:          Yeah, in my part of the world  [we have] canary grass and [purple loosestrife]; [yeah], same idea exactly. So, we are charting around, kind of, this wheel if you [will], [that you] see in the article these ideas that, well there is climate change, here is where the cliff looks like it might be; we are getting dangerously close to [it] biodiversity loss—[we're] over the cliff already on that one. Nitrogen, we have seemed to be over the cliff. We are getting close to it on phosphorus, water, land use and other things. So, I would like to imagine the metaphor like we are on top of a plateau somewhere in the desert at night, in our car, and we are driving really fast in our car, and our headlights are off, and we don't even have a map. That is a dangerous way to operate. [Wouldn't it be good] to turn on the lights and have a map [of] where you think the cliffs might be before you drive off the edge? And so, that is really the notion of these planetary boundaries—let's see where we don't want to go.

Steve:          You mentioned in the article there are some people who are, kind of, against this approach because for various reasons. Why don't you talk about some of the objections to this approach?

Foley:          Well, yeah, I've been to…

Steve:          This is really a philosophical approach as much as a scientific one.

Foley:          Oh, yeah, absolutely. I mean the brilliance of this—and I really [have to] give credit to the folks in Stockholm; [they] are really the first to push this idea forward. The response to this I think, came in three categories. One was just the normal denialist, "Oh, [wait] there is nothing wrong, don't worry about it." A kind of thing we see in climate change and other environmental issues. Well, they are demonstrably wrong, so, I don't pay attention to that too much.

Steve:          If you go to our Web site, after I post this, you will see many comments from people who will explain in great detail and with much vehemence about why you are wrong.

Foley:          Yeah, well, I would challenge them to say, "Do you obey the laws of physics?" and "Where is your data?" and [until] we see both of those, I am not that interested. But I think it is important to respond to these kind of criticisms, and to be fully honest about it. You know we have had some, well on both sides [in] climate change, we see a distortion of science happen in a very public way by people on both sides of this issue now. And [while] that is really disturbing, the essential [tenets] of the science are still sound. It's just there is a lot of fury and [light] on the edges of it right now that is not very helpful. But the basics are very sound. This is what I would argue. But the two criticisms I took really seriously [when] we [had] this paper come out were, one, "Hey by putting a boundary, like a firm boundary on the edge, are you telling people it is okay to drive up to the edge of the cliff and stop in the nick of time and everything is okay? It's okay to cut down 99 percent of the world until you hit the limit and not the last 1 percent? Is that [what you're] trying to say?" Then, of course not, we are not saying that all. We are just saying that we continue to damage the environment more and more and more. At some point, you could break the camel's back; you know that the straw finally breaks the camel's back, if you will. And that is extremely dangerous. But it is best not to put so many straws on the camels back to begin with. You don't wait till the last straw. So that is one concern we took very seriously and I understand the debate and that will be going on for a while. The other, of course, is the [more technical]  pieces of like, "Well, I don't agree with where you put this number." And we tried to err on the side of caution. If we said, "Well the boundary could be between A and B, but were closest to A, we are going to set it at A. You know we are going to put the police [tape that says 'Do Not Cross' at A, just in case. So, we are trying to be very conservative, maybe on the too-conservative point of view, but [I'd] rather do that in otherwise. So, those were the kind of two sets of reactions from our peers and other environmental folks around the world. And so we are working on that and I am trying to think about that but like you said, it is more of a mental framework and philosophical framework, than it is a specific number. We are just saying well, like the idea of a tragedy of the commons or limits to growth or something, we're trying to, you know, here's a way we can bring together a number of different conversations around this one a kind of paradigm and see if it is helpful. And I think it might be helpful. We are hoping it will be and [we] are [eager] to see what your readers think of this.

Steve:          You said that are a few of these things that we are tracking, we have already gone over.

Foley:          Yeah, nitrogen.

Steve:          Nitrogen.

Foley:          Well, that's right. In the analysis—this was [all] originally published as a scientific paper in Nature last fall and then we see it again here in Scientific American in a more a distilled form—what we show is that in terms of climate change, in terms of nitrogen pollution into our waterways and oceans, and in terms of biodiversity loss, we have already caused irreparable harm to the planet. It doesn't mean that is the end of the world, but in those three areas, maybe the beginning of the end of the world as we have known it. You could argue [on] the climate change [one], but [on nutrient] pollution we have used so much [fertilizer] and so much nitrogen compounds are loose in the environment, it is hard to recognize our coastal oceans anymore; of the species that are gone [and] that kind of thing. Our inland lakes are almost ubiquitously polluted with nutrients, and getting green and slimy where they didn't used to be. So, you know, those things are changed [so] their almost irreversible and they are going to be with us, forever now.

Steve:          So, in that case, what is the up sign to stopping? If I have already fallen off the cliff, is there something I can do to reverse my fall?

Foley:          Well, there is falling and there is throwing yourself off the cliff [as fast as you] can, because you are taking down a lot other things with it. The pollution we have nitrogen is more localized. We are seeing a lot of this in the upper Midwest in wells, near cornfields; a lot of them are polluted with nitrate. We are seeing nitrate pollution in the Gulf of Mexico and a lot of our coastal oceans near the mouth of rivers that are downstream from Big Ag production regions that use a lot of fertilizers. We can slow that; we might be able to reverse some of this damage. But it is also we have to make sure this doesn't spread to other parts of the world. So, there is another fallacy to this paper; in some ways, it would be pointed out to us, "Why are you giving us one number for the whole planet?" For climate change, that might be okay, but for pollution levels, they are often more localized, so how do you set a limit for, you know, Iowa versus, you know, Italy versus Kazakhstan. They are regionally specific in some cases. That's where more science needs to be done.

Steve:          But again, this is a framework, not a finished argument.

Foley:          No, yeah, exactly. Exactly, this was the most, we intended this to be a thought provoking piece, where we [say,] "Look, the numbers here are less important than the framework and the framework can be adapted, revised." But, you know, the idea of pulling this altogether, of wait there may be boundaries beyond which we do not want the environment to go, either because they go in to a tipping [point] and fundamentally change or because you['ve caused]  [a] near-irreversible amount of damage. And [that was really] the whole point of this, and I am hoping that this idea is useful. If it is not, we will come up with better ones, but this is the idea that we are trying to, it seemed to resonate with people across a lot of different backgrounds and disciplines. So, it began to be a framework where ecologist[s] and climate experts and chemists and other people concerned about these issues, all could say, "Hey, I see where I fit in this." And we all have a similar story, and [that] kind of tied it all together.

Steve:          What about economists?

Foley:          Yeah, well, increasingly, economists are recognizing the needs to think about living in a finite world. We based our economy forever on the idea of infinite resources, infinite frontiers and infinite exploitation and infinite substitution; that we could, well we ran out of this, we will find something else. You know, infinite growth is not really possible anymore, we are beginning to realize that. We [have] know[n] that for years but the economists are also realizing this too, which is great and so [now we have] the idea of putting a value, an economic value on the environment itself. The ecosystems have value even if we don't use them for crops or for timber; they store carbon and they regulate the water we drink from flooding or becoming polluted; the bees in the environment help pollinate our crops and so on. So, this has been a real revolution in economics to really take into account the value of a pristine environment or at least a healthy one. And so that is [a] great way to help frame these issues, because at least for me, I am not a tree hugger, I am not an environmentalist. I am an environmental scientist. I originally trained in physics and astronomy. So, I look at these things [and] say, "Well, I care about them, because this is really about people." This is about our economic security. This is ultimately about our health and our welfare and about [how] our children [are going to live] and this is a pragmatic issue. And if we can find ways that are economically and socially viable to keep our planet from going to dangerous territory all the better.

Steve:          Yeah, it is a point that you need to make over and over again, but we are not saving the planet—we are saving humanity.

Foley:          Yeah.

Steve:          If we do wind up doing the right things in improving the quality of life; because, you know, the planet's just [going to] get rid of us like a bad case of fleas. It is the people who are, and [he] used [a] construction that we don't use on this podcast to describe it. But I just wanted to say we are actually talking on February 19th. And on February 18th, the British paper the Guardian published an article, and let me quote from the article: "The cost of pollution and other damage to the natural environment caused by the world's biggest companies would wipe out more than one-third of their profits if they were held financially accountable a major unpublished study for the United Nations [has] found." Because, we never do take into account, the economic value of the environmental services that we get …

Foley:          Yeah.

Steve:          … from the natural world around us. Just in terms for example, water filtration.

Foley:          Exactly.

Steve:          Ordinarily, a city might have to pay for that and then it would be on the ledger somewhere, but if you have some kind of [a] wetlands that does it for you, it seems like it is free, but when you destroy [that wetlands], then you find out what the economic worth really was.

Foley:          Well, yeah, precisely and we have seen terrible examples of that after the Christmas day Tsunami in Asia recently where we saw, for example, a lot of people pointing out [that] places where mangroves were left intact had much less damage into the coastlines than the places where the mangroves were cleared for shrimp farms or other things. So we see, you know, environmental protection that way; we see in places [that] ha[ve] severe mud slides, [Honduras] a number of years ago after Hurricane Mitch, the areas where forests were left intact didn't see nearly as much damage. So, yeah, we have seen huge economic advantages during disasters of keeping an intact ecosystem. Just think of New Orleans and the coastal wetlands and so on after [Hurricane] Katrina. But at the same time, we also should recognize that even in the background, like wetlands, forest, healthy ecosystems and so on, are doing a lot for us, that, you know if they sent us a bill it will be a lot—one providing oxygen into the atmosphere. I like oxygen. We all need that right?

Steve:          I am breathing it right now.

Foley:          Yeah, I am a little bit anyway. And yeah, we have ecosystems [that] are storing carbon and keeping it out of the atmosphere, a lot of that actually. That's pretty helpful, that help keep[s] our climate in check. It is helping you regularly; the flow of water through our soils and rivers to keep it cleaner and so on. And also, bees you know, and pollinating insects, we've been so concerned about them disappearing in certain places in the world recently. Well, you know, this is a joke and I am not saying this, you know, maybe they just went on strike, we weren't paying them. No, of course, that is not what is happening, but again, there's been a incredible revolution [in what's] being called ecological economics, in the idea of the value of ecosystem goods and services. Like wait a minute, maybe we should not just put a fence around nature and say, "Thou shalt protect this, because it's good," but say, "Wait a minute, this is worth something, this is worth a lot. And if we have to put a dollar figure on it, so be it." There are other ways we value things; we value avoiding risks more than we value money. You know, we buy insurance, we do all sorts of things. You know, we are very risk averse in terms of things like national security and terrorism. We have spent a lot of money fighting terrorism; more than the insurance agencies would say a human life is worth, but we don't want that to happen. So, that is valuable. We have cultural amenities too like our national treasures and parks, we don't want those to go away either. So figuring what the value of these environmental services are is really important to make sure the human side of the human environment system is really represented. And that is pretty crucial I think.

Steve:          And again, this is going to be the beginning of the discussion. And are you going to actually check in with the magazine and the Web site to see?

Foley:          Yeah, I would be happy to. So, [in] a blog kind of feature or the comment section yeah, I would be very happy to see what people write in, and I will be happy to chime in if there are some constructive questions or comments that are I can respond to, and so, I will be very happy to do that.

Steve:          You can read Foley's article "Boundaries for a Healthy Planet" in the April issue of Scientific American and on our Web site—it is part of a special section called Living on a New Earth—and see a video summing up environmental boundaries on the Scientific American Web site. It is in the video area and it is embedded in the blog titled "Is the Earth Past the Tipping Point?"all at

And now it’s time to play TOTALL……. Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL……. Y BOGUS.

Story number 1: A survey of British children found that 70 percent of nine- and 10-year-olds would like to be famous for wining a Nobel Prize in science.

Story number 2: Speaking of Nobel Prize winning scientists, two Nobel physicists recently portrayed two other Nobel physicists in a production of the play Copenhagen.

Story number 3: The Large Hadron Collider will close at the end of 2011 for up to a full year for additional construction.

And story number 4: Researchers have found that you leave a chemical signature on whatever you touch that is as unique as your fingerprints.


And time's up.

Story number 1 is true: 70 percent of British nine- and 10-year-olds would like to be famous for winning a Nobel Prize in science, but among 11- to 15-year-olds, only 33 percent still share that wish, perhaps because they figured out that winning a Nobel Prize in science is no way to become famous. John Bardeen won two and I bet people would have knocked him out of the way to get a glimpse of Charo.

Story number 2 is true. Nobel Prize–winning physicists Alan Heeger and David Gross played Nobel Prize physicists Niels Bohr and Werner Heisenberg in a recent production of Copenhagen at Santa Barbara's Music Academy of the West. Stephanie Zimbalist was the female lead; you probably would remember her from the NBC series Remington Steele. See, I told you that winning a Nobel Prize was no way to become famous.

And story number 3 is true. The Large Hadron Collider will close at the end of 2011 for up to a year so that joints between the machines' magnets can be reinforced, as well as some other additional construction. Until then, the collider can't crank up to its full potential. Also, this way the LHC can't be blamed if the world ends in 2012. Because of the Mayan calendar thing. By the way on March 19th, the LHC broke its own record by creating beams of protons at an energy level of 3.5 trillion electron volts.

All of which means that story number 4, about leaving a unique chemical signature on everything you touch, is TOTALL……. Y BOGUS. But what is true is that researchers did find that you leave a unique assortment of bacteria on stuff you touch. Your bacteria will certainly be different from mine; so on analysis of the bacterial residue at a crime scene could potentially help identify a perpetrator. For more check at the March 16th episode of the daily SciAm podcast, 60-Second Science.

That's it for this episode. You can get your science news at, where you can find out how to enter our World Changing Ideas video contest and follow us on Twitter, where you will get a tweet every time a new article hits the Web site. Our Twitter name is @SciAm; I tweet as @Steve Mirsky. For Science Talk, the podcast of Scientific American. I am Steve Mirsky. Thanks for clicking on us.

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