MS. DIANE REHMThanks for joining us. I'm Diane Rehm. For generations, conservationists have been seeking to save nature from human intervention, but many say human population projections make this goal increasingly unrealistic. A growing number of environmentalists argue our only choice will be to learn how to better coexist. Joining me to talk about conservation for the 21st century, Jason Mark, journalist and author of a book titled "Satellites In The High Country: Searching For The Wild In The Age Of Man."

MS. DIANE REHMStuart Pimm, chair of Conservation Ecology at Duke University. And joining us by phone, Ursula Heise, professor of environmental humanities at UCLA. I do invite you to be part of the program. Give us a call, 800-433-8850. Send us your email to drshow@wamu.org. Follow us on Facebook or send us a tweet. Thank you all for being with us.

MR. STUART PIMMThank you so much for having us here.

MR. JASON MARKThank you, Diane.

MS. URSULA HEISEThank you for inviting me electronically and via phone.

REHMIt's my pleasure. Stuart Pimm, I'll start with you. Let's talk about the greater sage grouse. This grouse, the Environmental Protection Agency, decided not to list on its endangered species list. Tell me why that's so important, what it means to you.

PIMMI think many of us are very concerned about the decision of the Fish and Wildlife Service not to list this species because the Endangered Species Act has been an amazing success story. It's brought our nation's bird, the bald eagle, back to nesting in every one of the 49 continental states, many other success stories. And so I think many of us are worried that this decision will not protect the bird and it will not protect the iconic landscapes of the West which it represents.

REHMDo you think it represents a larger shift in thinking on the part of the Environmental Protection Agency?

PIMMI think the issue is that we all understand we have to make deals. And this is a deal. It's a deal with landowners. It's a deal with oil interests. And so the question is, is this deal going to work. And I think many of us are cautiously optimistic that it might, but I think it's going to need very, very careful monitoring to insure that the bird doesn't decline further.

REHMBut if you're looking more broadly, not just at that particular bird, do you think that there is a shift in thinking about endangered species going on within the Environmental Protection Agency?

PIMMI think there are concerns that somehow we need a new approach to conservation. I am completely unimpressed. I think if you look at the way the federal agencies, the conservation practitioners for half a century have been doing conservation, we fully understand that we need to work with local communities. Many people who are asking for a new vision, I think, are just poorly informed.

PIMMI think the ingredients of the right vision have been there in place for a long time.

REHMTurning to you, Jason Mark. You've just written a new book titled "Satellites In The High Country: Searching For The Wild In The Age Of Man." Now, how does that fit into the overall picture of the Endangered Species Act and the actions of that administration? Do you see a new vision ahead?

MARKYeah. I think, you know, with regard to the sage grouse question that what was sort of new about it was the federal agencies, I think, finally catching up, as Stuart says, with 50 years of best conservation practices. We know now that it's not enough to try to save single species. We really need to protect and safeguard entire ecosystems, entire landscapes. And so this compromise -- and Stuart's right. It really was a compromise and, in some ways, kind of a Solomonic decision that probably didn't please most of the environmental groups and in some way, probably didn't please the natural gas, oil firms and the ranchers in the West.

MARKNobody was exactly pleased with this compromise, I think, fully. The federal agencies, though, were trying to figure out a way, yes, how do we protect an entire landscape. And as I write in the book, I think these challenges -- the conservation challenges of the 21st century are just becoming more acute than ever with 7 billion people on the planet and with, of course, global climate change.

REHMSo what are you suggesting as what you see as a shift and what you think should be a shift?

MARKSure. I think, and what I write about in the book, is that the big challenge, I think, for conservation biology -- and Stuart is quoted in my book and he was very helpful to me in kind of parsing some of these issues -- is where and in what places and what times do we decide we're going to intervene to save a certain species and where do we decide that we might have to just let evolution continue to roll.

MARKAgain, because we're going to have to make hard decisions. There are going to be winners and losers as climate change and the effects of climate change become more intense. And unfortunately, we may not be able to save everything. There are going to be hard triage decisions, I think, coming down the pike in the later 21st century and that's--the hard choices are going to be where do we decide to perhaps engage in the assisted migration of, say, the pica, a small alpine rodent.

MARKDo we decide to help the assisted migration perhaps northward or upward in slope of the white bark pine or of the Joshua tree? The changes are happening so quickly that the natural systems can't keep up with them. And so these choices are just going to get harder and harder.

REHMAnd turning to you, Ursula Heise, talk about the history of what we've chosen to conserve and how we might think about that going forward.

HEISESo I think what's interesting about the sage grouse decision is that it was a procedure whereby you don't actually impose the force of the law, but you use the possibility of using the Endangered Species Act to forge consensus, to forge a coalition around protecting vast areas across 10 western states. So bringing together federal agencies, state agencies, quite conventional mining and ranching interests, private landowners, to create a vast protected area for the sage grouse.

HEISESo it's an interesting use of the law, where you don't actually use the law itself, but you say, okay, let's try and see if we can forge a coalition here to protect the species and the ecosystems it inhabits and then if that doesn't work, the law remains as a possibility. I think that forging of consensus is what's really crucial and I think that's where the older idea of fencing off areas or restricting their uses for local communities sometimes has worked and often has not worked, especially in places such as Africa, certain places in Southern Asia and Latin America where the conservation movement, perhaps unnecessarily has made enemies of local communities and indigenous people who over the whole last century have been displaced or severely curtailed in their uses of lands that they consider ancestrally theirs.

HEISENow, Stuart Pimm is, of course, right that since the 1990s, many major environmental organizations have become better at forging these consensus deals with local communities, but we still see the conflicts going on. Elephant poaching has become, once again, a major concern in Africa. The International Indigenous Forum on Biodiversity walked out on a meeting of the Convention of Biological Diversity in 2008. So these conflicts over who decides what land gets set aside and what it's used for are, by no means, settled.

HEISEAnd that's where, I think, the sage grouse deal is promising and there's another one that has just come down in California, the Desert Renewable Energy Plan, that the BLM has just handed down, which set certain areas of desert aside for species protection and then will make other accessible for a generation of solar energy, another important environmental goal.

REHMUrsula Heise of UCLA. She's author of the forthcoming book, "Imagining Extinction: The Cultural Meanings Of Endangered Species." If you'd like to join us, 800-433-8850. Send your email to drshow@wamu.org. Join us on Facebook or send us a tweet. Stuart Pimm, you seem more concerned about the species, the individual species, than the larger landscape.

PIMMI think that's not true. You know, the Endangered Species Act says in its front page that the purpose of the act is to protect ecosystems and the species that depend on them and I think that's exactly right. I think we understand that when we're concerned about spotted owl, that we're also concerned about the forest where they live.

REHMAll right. And we'll take a short break here. Stuart Pimm is at Duke University. Jason Mark is the author of "Satellites In The High Country." We'll take a short break here. Your calls when we come back.

REHMAnd welcome back. If you've just joined us, we're talking about various approaches to saving species. There is a new debate out there as to whether our approach to focusing on individual species has been the right way in the past and perhaps now needs some tweaking. Here in the studio is Stuart Pimm of the School of Conservation Ecology at Duke University. Ursula Heise is on the line with us from UCLA. She's professor of Environmental Humanities. And Jason Mark is a journalist and editor of SIERRA magazine, author of the new book titled "Satellites in the High Country: Searching for the Wild in the Age of Man."

REHMAnd Stuart Pimm, just before the break you mentioned Africa. I know you wanted to talk further about that.

PIMMYes. I mean, Africa is a very obvious place where iconic species, such as lion, bump into some of the poorest people on Earth. So how do we manage a species like the lion. I'm very fortunate to work with a program that National Geographic has called The Big Cats Initiative. And what we help people do in Africa is to protect their cattle at night in structures called bomas. And if the lions can't get in to kill the cattle, then the people don't need to retaliate and kill the lions. And I think National Geographic's Big Cats Initiative is a model of recognizing that people do have conflicts with wildlife, and yet we can work out solutions that allow people and wildlife to coexist.

REHMJason Mark, talk about your book, when your subtitle reads, "Searching for the Wild in the Age of Man." How does that work into the environmental approach to protecting the wild in our universe?

MARKSure. I think a lot of this debate about what some have called a battle for the soul of conservation. And what is truly a debate within the field of conservation biology is being fueled to some degree by this idea that first started with Earth scientists, that we've entered a new geologic age, what's called the Anthropocene or the human age, as I say in the title, "the Age of Man. And the basic takeaway is that human and human civilizations are now the largest evolutionary force on the planet. And if that's the case, where does wildness fit and where does wilderness fit? And it's not just a question for philosophers or academics.

MARKIt really plays out again on the landscape level, where we have to make tough decisions about both sparing land -- setting some places aside for other critters -- and also sharing land, as Stuart was just talking about -- finding ways, as you mentioned in your introduction, to coexist.

REHMSo give me an example of where this is actually taking place.

MARKWhere it's playing out. I think, in large part, it often gets down to predators and large carnivores. How do we find ways to coexist with other things that are also like us, at the top of the food chain. In North America, that basically means bears, mountain lions and wolves. And if you think about the long-running, burning controversy, which I address in "Satellites in the High Country," the controversy about reintroducing wolves to the American West. It's been now a 20-year-long, running political battle -- the wolves, listed on the Endangered Species Act, pulled off the list, hunting now resuming in the Northern Rockies.

MARKI, for the book, tracked the population of Mexican gray wolves in the Southwest. There's only 106 of them in the wild and they are probably the most heavily monitored and managed wildlife on the planet.

REHMSo when you say, making room or making space or allowing man and wild animals to live together, are you saying that certain spaces simply should be designated for that wild animal and certain spaces should be kept for man?

MARKI think, again, we have to do a little bit of both. We have to both spare some land -- and, yes, that means setting aside large, intact ecosystems, again, using bedrock American environmental laws like the Wilderness Act to, for example, set aside in this country now 110 million acres of land. And at the same time, we need to find spaces we can share. You think about the comeback of the mountain lion in the American West -- mountain lions now living inside the City of Los Angeles. A mountain lion, spotted for the first time in more than 100 years in the City of San Francisco this year.

MARKWe need to find ways both, again, to coexist in some places and also to set aside those large, remote landscapes.

REHMSo how do you see the decision of the EPA not to list the greater sage-grouse as an endangered species, fitting in to your view of how man and wild creature live side-by-side.

MARKI would echo Stuart and say I'm cautiously optimistic. I think it's going to be -- and we're going to see if it works. Stuart said earlier, before we got on the air, that it's sort of like throwing the ball way down the field and hoping that someone's there to catch it in 10 or 15 years. We're going to have to see if this works. This is an attempt at sharing landscapes and, again, a compromise between the ranchers, the oil and gas interests and the environmental and conservation groups. So it's an experiment.

REHMAnd Ursula Heise, how do you see it?

HEISEWell, I think, as I mentioned, that the sage-grouse compromise is a good model for what we might do to protect relatively wild areas. And I think it's a model also for what we might want to do going forward with landscapes that are not as wild: agricultural landscapes and, indeed, urban landscapes. And I think that's where the really new and exciting movements in conservation are currently taking place. Agriculture is one of the most dangerous things for other species in the sense that we grow things for our human needs and to a certain extent sometimes create habitat. But we also destroy a lot of habitat for other species, especially with monocultures.

HEISESo thinking about ways to reform agro-ecology in various places around the globe, move away from monocultures, and make agricultural landscapes ones that are productive for humans but that also create habitat for all the non-human species -- animals and plants -- that we want to preserve. And, of course, cities are now an area where conservation is burgeoning. We have a big project afoot in Los Angeles for the revitalization of the L.A. River, that might include the reintroduction of certain native species into the L.A. River, such as frogs, turtles and snakes.

HEISEAnd so there, of course, it becomes absolutely paramount to work with the communities that live along the river to make sure that they actually want these species around and that they're willing to protect them.

REHMAnd Stuart Pimm, what are other European countries doing in this area to preserve a strong biodiversity?

PIMMI mean Europe is a very intensely populated part of the planet. I mean, it's broadly comparable to the Northeastern United States. I think the lesson that comes out of Europe is that biodiversity is really valuable to us. We want green spaces. We want nature. We want to see wildlife. And, you know, when we are setting aside our national parks -- and globally the areas set aside in national parks has tripled in 25 years -- it's a reflection of how valuable those places are. You know, when we had the last government shutdown, you'll recall, the national parks were specifically excluded, you know, because with 300 million visitors a year to our national parks...

REHMMoney.

PIMM...money. They're valuable. So I think Europeans fully understand that we have -- there has to be a place for nature. And in many cases, it's entirely economic self interest.

REHMAnd what about places like China? What about India?

HEISEBut, Diane, if I might add something to that. I think...

PIMMIndia has some amazing national parks. And it's been challenged because people were living in them. And in some cases, people were evicted from those national parks in very brutal ways. And nobody approves of that. One of my students, Krithi Karanth (sp?) , studied a park in India and realized that if you encourage people to life outside it and you give them the right incentives, that was good for the people and it was good for the national park. There are ways of making these deals work.

REHMAll right. We've got some callers. Let's go first to Carol in St. Louis, Mo. You're on the air, Carol. Go right ahead.

CAROLOkay, thank you, Diane. I so much appreciate your show.

REHMThank you.

CAROLI just wanted to make a comment about -- folks mentioned the inefficiency of the Endangered Species Act and its focus only on, you know, the narrow needs of a species. I think that's been a little bit unavoidable, sometimes for political reasons. I think the folks at Fish and Wildlife that work with the Endangered Species Act realize the broader picture. And I just wanted to mention, here -- I'm from St. Louis and I work on Missouri River issues.

CAROLAnd we have three threatened and endangered species in, along and in the river: the pallid sturgeon, piping plover (which is a bird) and the least tern. Currently, the Army Corps of Engineers is looking at these three species and trying to come up with a decision that will, what they call avoid jeopardy, and meaning avoiding hurting these species. But they're actually blocked because of some political action from looking at the broader restoration needs along the river, whereby they could look at broader habitat restoration that would not only help these three species but could also address some other needs along the river, such as reducing flood risk and providing overall habitat needs for migrating birds, et cetera, and provide recreation for folks...

REHMHmm.

CAROL...that live along the river.

REHMSure. Stuart, do you want to -- sorry, Jason, do you want to comment?

MARKWell, I guess my comment would be, again, I think the caller gets it right. You know, you've got at least three species I heard of concern in her comment. And the solution is to, again, protect and if necessary restore the entire ecosystem. I think, again, our goals are driven by wanting to save specific species. Because, you know, to cast something into the kind of great void of extinction is -- I don't think it's -- you can say it's a sin, right, to actually, you know abolish this thing forever. So that's what's driving us, this crisis in biodiversity. The solution, again, is to think about its entire needs for its entire landscapes. And that's going to have beneficial effects for a lot of other critters.

REHMBut...

HEISEBut, Jason, it's interesting to think about...

REHMShe's talking about three specific creatures. And the question becomes, do you set aside a total landscape for those creatures? Or do you focus strictly on keeping those three creatures alive?

MARKI think by doing the first thing, by setting aside the entire landscape, you will accomplish the second.

REHMAll right, Ursula, I know you wanted to jump in.

HEISEYeah, I mean, I think it's actually interesting to compare, in response to the caller's note that maybe it's unavoidable to focus on individual species, that's actually not the case in all of nature protection laws. Many countries around the world actually do not have endangered species laws. They have biodiversity protection laws. That's one crucial difference, for example, between Germany and the U.S. So it's not inevitable that we need to focus on species.

HEISEAnd in Germany, it's not the notion of wilderness that has driven conservation but the notion of Landschaft, or landscape, which in Germany has always meant culturally shaped landscapes that have existed for the last millennium or so and which often include human habitation and human transformation. So forests that were used as pasture since the Middle Ages, those are the kinds of landscapes that German conservation seeks to restore. So I think, when we talk about wilderness and about the American approach of setting aside areas, it's also worth remembering that the notion of wilderness has been most influential in the environmental movements of English-speaking settler colonies: the U.S., Canada, Australia.

HEISEAnd in other countries, there's other really powerful concepts that have shaped conservation that we might want to look at.

REHMAnd you're listening to "The Diane Rehm Show." Let's go now to Katherine in Cary, N.C. Hi, there. You're on the air.

KATHERINEHi. I'm a wildlife biologist. And what drove me into the field was the focus on habitats, not individual species. And having done policy work for about eight years in Washington, D.C., and then coming to NC State to work on my PhD, where I'm having a social-science look at how sciences can work with citizens in the decision-making process, it's become quite clear that, you know, the way we have to move forward in the 21st century is educating people.

KATHERINEYou can start with the youth, the conservation education. Letting them learn what the species are, how the strong connection with the land, like they have with their computers and their fashion, so that they know what -- how they impact the land and hopefully carry that on into the future, no matter what profession they take on. And then using citizen science research is a way to draw adults into the process so that they are a part of collecting the data that helps the scientists analyze the data. They see how the data they collected is used. And that draws -- that makes them even more connected to the animals and the landscapes with which they live to know how to alter their own lives.

KATHERINEAnd, bottom line, I think Ursula was really doing a great job of trying to provide examples of how you can have humans and wildlife coexist. You know, the Farm Bill has to be, I think, reformed where you're not looking at pockets of habitat for wildlife but you look at the entire agricultural landscape as a haven for wildlife, for instance, just, you know, a waterfowl. So that you're looking at all the areas in which the waterfowl are using, not just one particular farm, which is what the Farm Bill is focusing on.

KATHERINESecondly, I've been to a bio-reserve outside of Cape Town, South Africa, where you have a zoning level. So it is focusing on biological diversity, like people do in Germany and having the landscapes, but you've got the inner core, which is where nobody can go in. It's just for the wildlife. And then you start zoning out to having limited human actions in those environments, and then even more. So it could be, you know, winery production and tourism. And then -- so there is a way, as you recognize what the needs are of the animals.

KATHERINEBut, you know, we have to get away from focusing strictly on the environmental laws of the past. Because they are trying to bring in old landscape ideas of what we should preserve and not the new ways in which humans interact with them.

REHMAll right. And we'll address your comments after a short break. I hope you'll join us, 800-433-8850. Stay with us.

REHMAnd welcome back. Several times I made reference earlier to the Environmental Protection Agency, and of course it is the Fish and Wildlife Service in the Department of the Interior that administers the Endangered Species Act. Here's an email from Mike in Michigan, who says, I'm curious how these conservationists look at the big picture, such as not only an incredible number of human beings in the future but the understanding that due to global warming, huge and exploding populations will be displaced by geographic necessity. Jason.

MARKYeah, that's exactly right. I mean, that is clearly the biggest threat, I think, globally for conservation is the fact that species, flora and fauna, are going to be dislocated from their longtime habitats, pushed from their homes. That's what dislocation means, right, pushed from their homes, again poleward or perhaps upward in slope. And the challenge for conservation, and this kind of gets back to what the caller from North Carolina was talking about, just having the large protected preserves is essential but insufficient. In addition to having these large preserves, we're going to have to create corridors connecting wild lands, and a lot of that's going to happen on private lands, and much of that's going to have to happen on ag lands, right.

MARKWe're using roughly 40 percent of the world's ice-free surface for human use, and much of that is to feed ourselves. So we're going to have to find a way to also thread some wild (unintelligible) and wildlife corridors through agriculture and knit together spaces so that plants, animals, birds can move. And that's the great challenge is to basically connect these reserves, these refugia.

REHMUrsula?

HEISEIn 2008, the WHO pointed out that humanity now lives -- the majority of humanity now lives in cities, many of them in quite large cities. And I think that in response to the caller is actually the biggest new development that now most of Homo sapiens from now on will live in cities, and most of the population growth of the future will either start out in cities or end up there. So that makes it all the more important to think about conservation in cities, and there's really exciting new thinking occurring now in conservation about how we might rethink urban planning, how might we acknowledge that cities are already places that other species co-inhabit with us, and how can we make them even more hospitable to other species.

HEISEIn architecture, we can think about how can we reconcile the beautiful, sort of smooth, modern buildings that have no nooks and crannies, with big window fronts that are often quite dangerous for songbirds, how can we reconfigure them in such a way that they offer habitat not just for us humans but also for other species, the songbirds, the reptiles, the rodents, the insects, so that cities can become bio-cities, that cities can actually become biodiversity hot spots. I think that's a really exciting new frontier in conservation and one that will require a lot of ingenuity and innovation but where it's really exciting to think about how we can redesign urban space so that it becomes a multi-species city, not just a human city.

REHMStuart Pimm?

PIMMYou know, not only have we destroyed large areas of habitats, we have fragmented them. We've left what remains in pieces, in tatters. And one of the solutions that my group, a nonprofit called Saving Species, does is to go to the parts of the world where the greatest number of species are at risk of extinction and then help local conservation groups reconnect nature. We connect, protect and restore, CPR for Earth, by connecting the pieces, by restoring these isolated patches. And that's essential for Jason's point that we need to allow species to move, and they can't move if they're isolated from each other. You've got to create these corridors.

REHMAll right, to Phoenix, Arizona. Aaron, you're on the air, go right ahead.

AARONHi there. Mike from Michigan might have stolen a little of my thunder on this question, so I don't want to redundant. Politically, what sort of legislation would be in place to protect the deforestation that might there otherwise occur for these agricultural needs? Are there certain trump cards that the environmental movement might be holding that can prevent fast and radical change by agribusiness and, you know, resource, energy resource needs?

REHMUrsula?

HEISEI think it's crucial, again, to build consensus, to work with the owners and with the companies who are -- who own the land and to certainly educate them in good conservation science. But when you look around the world, also learn from communities that have already worked the land for millennia and then transform agricultural practices, sometimes transform them back to what they used to be when they actually did support a lot of biodiversity.

HEISEAnd so I think the crucial point here, before you bring in the law, which is important, and we certainly need regulation, is to create consensus and to bring in all the stakeholders around a certain area to create habitat that goes beyond human needs. So make sure that the human needs are fulfilled but also that we always create habitat for the plants and species on which we depend.

REHMJason, I know you have visited some of the Earth's wildest places. Talk about where they are and what you've seen.

MARKSure, so I mean, again the book "Satellites in the High Country," I set out to explore, is there anything that's still really, truly wild in the 21st century, and if so, how do we hold on to wildness as a touchstone with our relationship with the rest of nature. You know, clearly one of the kind of boldfaced names of global wilderness that I went to for the book would be the Arctic and the Arctic National Wildlife Refuge. And even there, a place that's so remote from civilization, the fingerprints of civilization are clearly, clearly on the landscape because of climate change, because of global warming, et cetera.

MARKAnd I think the takeaway there is to recognize that while we might live on what I'd call a post-pristine planet, that wildness is more important than ever, again recognizing that we need to save place for other critters precisely they're other from us, right. We just -- we don't want to live alone in what EO Wilson, the great Harvard biologist, has said, rather than the Anthropocene, we might call this the aramazoic, the age of loneliness. We don't want to be the only thing on the planet. And so I think these issues of conservation become more intense in the Anthropocene, not less.

REHMBut are there any areas truly untouched by humans?

MARKNo, I don't think so, not at this point.

PIMMBut, you know, it's a relative thing. There's still lots of the planet that is spectacularly beautiful, that gives us that enormous sense of how beautiful our planet is and what...

REHMGo ahead.

PIMMAnd how special is our responsibility of stewardship.

MARKAnd I agree with that.

REHMBeautiful but with humans as part of it.

PIMMTo varying degrees.

REHMOkay, and Ursula, you wanted to jump in.

HEISEI just wanted to point again to the importance of cultural diversity. Wildness is not the touchstone of conservation everywhere in the more. I already mentioned the German example of Luntzhoft (PH) in Latin America there. Now a very exciting experiment is under way to actually integrate thinking about the pachamama, the Mother Earth of indigenous cosmologies, into law and even into the constitutions of Ecuador and Bolivia.

HEISEIn Japan, the notion of Satoyama, the village and creek by the mountain, something akin to our pastoral, has shaped the love of nature for centuries. So I think it's important to think about these different ways of structuring the love of nature, which is not always about wildness. And it seems to me that one good way of thinking about what we might do with this planet that, as you say, Diane, has been in some sense completely transformed by humans in the sense that there is no area of the planet that's untouched by climate change and ocean acidification, would be to think about it as a matter of justice, not so much how do we preserve or restore what was there in the past but how do we right by people and by the non-humans who co-inhabit the planet with us.

HEISESo thinking about something like multi-species justice, I think, is a really productive way of framing different cultural understandings of how we live with other species.

REHMI guess the question for me is with the population growing as it is, is the human population going to crowd out the wild population? And if not, how do you prevent that from happening?

PIMMAgricultural or croplands only take up about 15, 1-5, percent of the Earth's surface. So there's an awful lot of nature out there that we use in a less intensive way. There are still large areas of forest. There are still large areas of rangeland. There's still big chunks of the Arctic. There's big deserts. There's the Tibetan plateau. There's a lot of nature left. Now with the Amazon, people think of the Amazon as a wilderness. It's full of people. And you can look at the imagery on Google Earth. You can see where people live, indigenous people live in the Amazon, because that's where the forest remains. The people look after their forest.

PIMMSo there are still a lot of opportunities to have a lot more people and look after and be good stewards of what remains.

REHMBut the world, the globe itself, is not going to grow any larger, but more and more people are going to inhabit it and not that many people are going to want to live in the rainforest. As you've all said, more and more people are going to want to congregate in urban areas. So what is that going to do as those urban areas expand and crowd out that wilderness for wild creatures?

PIMMWell, urban areas are about two percent, maybe three percent, of the planet.

REHMNow.

PIMMNow.

REHMNow.

PIMMEven if it were three or four percent, there would still be a lot of nature left. It's a matter of being smart.

REHMAre you concerned about that, Jason?

MARKWell, concerned about global human population for sure, and I think it remains an ecological imperative, and sort of Ursula would say, an issue of justice for ourselves, being able to share equitably among humans the Earth's finite resources and share equitably among the other species. We need to stabilize the population and even I think urbanization is for the most an environmental good, again because we are concentrating folks. We're concentrating our footprint.

MARKWe know that a New York City has a lighter footprint than, say, a sprawling city like a Vegas or a Houston because its functions are concentrated. So urbanization in many ways is a great boon for conservation.

REHMAll right, let's go to Suzette in Pale, Washington. You're on the air.

SUZETTEHi Diane.

REHMHi.

SUZETTEI live in an area that is heavily forested and heavily logged. It's all private timber companies, thousands and thousands of acres around me, and my question is human waste, dumping, garbage. What does the conservation projects do about that? How do they tackle that issue not only in private timberland but in parks?

REHMAnd before any of you responds, let me just say you're listening to the Diane Rehm Show. Stuart Pimm?

PIMMWhen you said that large areas of Washington were in private hands, I was surprised by that because most of the West is owned by we the people, by the Bureau of Land Management, the Forest Service. And so an awful lot of logging that has threatened species like the spotted owl has done so because it's been logging on public lands where we the people now feel that we might get a better investment in our money from having them as forests than as having them as woodchips.

PIMMIn terms of rubbish, yes clearly we, as numbers increase, and our consumer society generates more waste, we have to do something about that. I think that motivates us to be very serious about recycling.

REHMUrsula?

HEISEI wanted to come back to the question of how we think about population in relation to urban areas and to problems such as encroachment on public lands and misuse of them. The human population isn't going to keep growing indefinitely. Most projections have human populations going down after 2100. So in part it's also thinking about the next 70 or 80 years and thinking about how we're going to manage our interaction with other species during that time. After that, we might be looking a very different kind of population scenario.

HEISEAnd already now in some parts of the world, populations are going down, not up. In Japan, some parts of Europe, in Russia, the population is actually shrinking, which creates its own problems both socially an ecologically, but we might be looking at a quite different -- at a quite different scenario 100 years down the line than 50 years down the line, and that's one crucial difference, also, with what things looked like 50 years ago, or 60 years ago in the 1960s, when population growth was global.

HEISESo I think we're looking at a different future, and the crucial, the crucial question is how can we think about the cities where population will indeed keep growing for the foreseeable future.

MARKYeah, I mean Ursula is right. The long-term projections do show human population stabilizing and starting to decrease. But as Ursula points out, that's in 70 or 80 years, and 70, 80 years is a long time for a species that's on the brink of extinction. You think again about, say, the African elephant. The African elephant might now have 70 or 80 years for us to get it right. And so while I, you know, I sort of share that optimism about the long-term trends, there's stuff we've got to get right right now in 2015, 2020, et cetera.

REHMSo what can be done, say, about the African elephant?

MARKWell in that case, I mean, probably sustaining the global ban on ivory and, again, trying to reduce demand in China and demand in other countries. That's...

REHMBut that doesn't seem to have been working so well thus far.

MARKIt's been very challenging for sure, and there's cultural things to change. And what -- I think that brings us back to the point which we've sort of flirted with this entire conversation, which is at the end of the day, conservation is -- it's not a scientific problem, it's a political problem. This is a democratic debate, as with everything, and we've got to pick priorities, and we've got to make hard choices.

MARKThe science, and the great science that Stuart and his colleagues do, they inform, the educate, they lead us, they ask the big questions. But fundamentally the answers come in the political arena, where there's a contest of visions and of values.

REHMIt's got to be pretty frustrating, Stuart.

PIMMYou know, it isn't. I feel enormously empowered. I'm fortunate to work with wonderful local people in South America, in Africa, in China. I see that they're competent and passionate, and they work out local solutions.

REHMWell, I'm glad to end this conversation on a positive note. Stuart Pimm of the -- he is Doris Duke Chair of Conservation Ecology at Duke University, Ursula Heise is at UCLA and author of forthcoming book "Imagining Extinction: The Cultural Meanings of Endangered Species," and Jason Mark, who is the author of "Satellites in the High Country." Thank you all so much.

MARKThank you.

PIMMThank you so much.

HEISEThank you.

REHMAnd thanks for listening. I'm Diane Rehm.