The Habitable Planet: A Systems Approach to Environmental Science
Biodiversity Decline Interview with Jeremy B. C. Jackson
Interviewer: What is your role in studying this global problem of marine biodiversity decline?
JEREMY: From the point of view of what I actually studied – the coastal marine ecosystems – the train has left the station and it’s traveling at higher and higher speed towards destruction. How do we stop that? There’s the social dimension; there’s the scientific dimension of it. In more immediate terms, a big part of my job is to tell people what they have to do to stop the destruction and maybe make it better. It’s not my job to worry about how much that will cost. That’s their job. I firmly believe that if we don’t stop fishing in a huge proportional area of the ocean, we’re going to go past a point of no return and we’re not going to have those species anymore. And it’s not a small amount. We protect less than 1 percent of the ocean. We have to protect a third of the ocean completely from fishing. Most people don’t believe that yet. But we’ve got good, really strong scientific reasons for believing that. It’s my job to stick to my beliefs and to continue to demonstrate as a scientist that these things are true. It’s my job to show that when the seafloor is leveled by trawling that there’s an enormous loss of diversity and why that matters, and to try to calculate — because I’ll be long dead before any of that recovers — to try to calculate how long it’s likely to take for that to recover. It’s my job to figure out what are the minimum things we have to do to stop the growth of dead zones and maybe reverse them.
Interviewer: Has the biodiversity of coastal ecosystems changed?
JEREMY: Coastal ecosystems have changed extraordinarily in terms of what they look like, what the habitats are like. And inevitably that has a huge effect on the abundance of difference kinds of organisms. It’s much easier to understand if you don’t think just of numbers of species but think about what kinds of environments used to be there and have disappeared, and what new kinds of situations have appeared. So mangrove forests or sea grass beds disappear and are replaced by areas of mud or coral reefs that get overgrown by seaweed for various reasons. The really big easy-to-see changes are enormous. And associated with that, all the creatures who depend on those habitats of course change a great deal as well.
Interviewer: Why should people care about marine ecosystems?
JEREMY: The ocean is really important to people in lots of ways, many of which they may not be aware. The most obvious thing is the food we get from the ocean. The shrimp and the table fish are a very important part of our diet in the United States and in Europe, but an even greater part of the diet of people living in developing countries especially in the tropics where it really plays a major part.
Every time we have a hurricane and we see the destruction of the coastal zone and we see flooding because forests have been cut down, because salt marshes have been destroyed or mangrove forests have been lost and the level of destruction is so much greater because those natural barriers have disappeared. The recent hurricane in New Orleans and the destruction of New Orleans- a great deal of the destruction – the magnitude of what happened there is due to the fact that the lands have been drained of the natural swamp lands that surround the city and provided a kind of protection. Then there are much bigger, larger scale things that are harder to understand about how the ocean helps to regulate the climate and just everything about the world we live in, in terms of its comfort.
The ocean is remarkably important for recreation. We’re getting to the point where something like half of humanity lives within a hundred miles of the ocean. Regardless of people’s economic well being, the, ocean attracts people. It’s a zone of recreation which holds enormous importance to people. Going to the beach for people who live in a urban area, provides an opportunity to escape for a day and go to a place where you can see beyond across the street and be in the water. All of these things are parts of what the ocean really means to us.
Interviewer: If the seas are being overfished, why don’t we see fewer fish in the market?
JEREMY: The United States is still the wealthiest nation in the world. And you can buy fish for a very low price unless it’s exotic. But if you go to a Costco or a store like that and you ask the question where did that fish come from? you’ll find that very little of the fish that you buy in a store in the United States actually comes from the United States. And so, because of our economic strength, we have been able to essentially exploit the fisheries of all the other nations in the world.
We eat fish that comes from the coasts of Africa, fish that come from the Pacific Islands, fish that come from Antarctica. And we are fishing harder and harder and further and further away. As a result, people in those poorer countries, they don’t have any fish at all in many cases because we’ve essentially bought it from them, usually in ways that entail a great deal of corruption. And so we don’t feel it, because we are using everybody’s fish. But even those fish from all those other places are on the verge of being, if not completely exploited, exploited to such extreme levels that people go farther and farther to catch fewer and fewer fish.
It’s widely acknowledged that something on the order of ninety percent of all the big fish in the open ocean are gone. And, there’s no question about where they went. We ate them. They’re not gone because of climate change or something like that. And most of that happened in the last fifty years. If you think about the movie The Perfect Storm, why were those people out there in the middle of the Atlantic Ocean to be destroyed by that wave? They were out there to catch swordfish. A hundred years ago they could have caught those swordfish a mile offshore from Massachusetts or Long Island. They had to go a thousand miles to catch smaller fish because virtually all the swordfish along the coast of the United States are gone.
Interviewer: How do you know that ninety percent of large fish populations are gone?
JEREMY: The person who wrote that paper used data from the Japanese fishing industry and the fishing industry gave them the data. It’s called long-line fishing – these enormous ships go out in the ocean and trail lines with hundreds of thousands of hooks behind the ship. The lines extend out for miles and miles behind the ship. They set those lines and then they pull them and they catch fish. The Japanese are extremely good at that. And they have a massive fishing fleet. And they kept very good records.
The data that these people – a man named Ransom Myers in Canada – and Boris Worm – that they used was the catch rate from this industry. Essentially the way to think of it is for every one hundred hooks put out by one of these ships in the beginning of a fishery, they would catch ten large fish. But within about ten or fifteen years, the rate drops to one fish every hundred hooks. And that’s ten percent.
In the beginning of the Japanese fishery, they fished mostly close to home. Then they depleted the fisheries in the Western Pacific so they moved into the North Atlantic and the South Atlantic and the Central Pacific and the Indian Ocean and all of the different fisheries’ grounds around the world. And what these people documented in their paper was that in a period of twenty-five to thirty years, in the entire global ocean, the catch was depleted from ten fish per hundred hooks to one fish per hundred hooks. That’s ninety percent of all the big fish are gone.
Another way we know about the magnitude of the fish we’ve lost is this remarkable man named Daniel Pauly, who has run a large fisheries research program for a long time. They got the data from the FAO, the Fisheries Agricultural Organization, in the United Nations. They started with the Atlantic Ocean and they got this global fisheries data and they figured out a way to take these data that were essentially commercial fisheries data of how much fish was taken out of the North Atlantic in 1900, in 1950, and today. And, they made maps. The red color meant that there were lots of fish and a white color meant there were no fish. Iin 1900, all along the East Coast of the United States and Iceland and Greenland and Western Europe, it is red. And, in 2000, it’s white.
Virtually the richest fishing grounds in the world are now essential defunct. The cod of Newfoundland – there were three World Wars fought about those fish. In the Seventeenth and the Eighteenth Century those fisheries were the most important commodity in the world; the way petroleum is today, codfish was then. And those codfish are gone. And when they finally crashed, thirty-five thousand people in Newfoundland lost their jobs. They’ve never come back. That’s finished. That’s gone.
Interviewer: Is taking data from fisheries really the most reliable, scientific approach to figuring out how the fish population has declined?
JEREMY: If you wanted to know what Manhattan Island was like as a natural ecosystem, you wouldn’t go to Wall Street and survey the birds. Wall Street has changed in the last five hundred years. And in the same way, if you want to know what kind of fish or whales there were in the ocean, think about a book like Moby Dick. Think about a movie like Master and Commander. What were all those whaling ships doing out there in the Pacific Ocean? They were catching the whales that aren’t there anymore. So, you could go out and do a scientific survey of whales today. But, it wouldn’t tell you anything about the abundance of whales. It would be a stupid thing to do if you wanted to have some idea of what whales were like before since some species of whales are extinct so it would probably be difficult to survey them to determine how many of them there used to be.
This is an example of what Pauly called the Shifting Baseline Syndrome. It’s an incredibly important idea. It’s the most important idea about understanding the environment and human impact on the environment. You cannot understand a problem just by looking at the way the world is now. Everybody, when they’re a kid, thinks that natural is the way the world was when they were growing up. And then they think unnatural is the way it is when they’re old, which is why old people are more depressing than young people. But kids never learn anything from their parents. And so they go out and they make the same mistake. We’ve been doing this for tens and hundreds of generations. Our power of denial is extraordinary. Scientists, fishery scientists, talk about baselines. The baseline is the way it used to be. But, every generation of fisheries biologists makes a new baseline when they start their career. And so the fisheries biologists from thirty years ago, their baseline was maybe ten percent of the fisheries biologists’ baseline from the generation before. So when these guys wrote their paper about ninety percent of the big fish being gone, their baseline was 1950.
You can imagine how many big fish disappeared before 1950. The real title of that paper probably should have been, “Ninety-Nine Point Nine Percent Of All The Big Fish Are Gone.” But even those of us who do historical ecology, we won’t push it that far because there’s a limit to what we think we can infer safely based on really good descriptions. You know, if I ask you the question who was President of the United States during the Civil War?, you’ll say Abraham Lincoln. And then I say, Well how do you know that? And, you say, I read it in a book. Nobody would deny that. Nobody would challenge it. But if somebody came along and asked me how many fish were there during the time of the Civil War off the coast of Cape Cod and I said, oh, my God, there were millions and millions of enormous codfish, they’d say how do you know? I’d say, Well, I read it in a book and I read all these fishery statistics and I read all this stuff about how many people made their living fishing and how many boats there were. And they’d say, oh, but you’re just a biased environmentalist. You don’t really know that.
Interviewer: If the big fish that are at the top of the food chain die out, how does that affect the food chain?
JEREMY: What happens when we take away parts of the food chain is a big scientific research question. And nobody knows all the answers to that. There’s a jargon term, we call it Trophic Cascades, but the simple way to understand it is big fish eat little fish. And the big question is, when you remove the things at the top, does the next level down just take over or is the balance disturbed in some kind of way that it’s not that simple? It’s pretty clear that it’s not that simple. And it’s pretty clear that we can’t control the outcome. And it’s pretty clear that not only do we not know how to control the outcome, but we don’t even know whether it’s going to be good or bad. I mean you could argue about those big fish. It takes them a long time to grow up. It takes them a long time to make babies. Elephants don’t grow as fast as rats. You could probably get a lot more meat out of eating rats than eating elephants because they turn over faster. So why not eat the equivalent of rats in the ocean instead of the equivalent of elephants in the ocean? And that sort of makes sense, you know? Because the productivity is higher and agriculture after all exploits something like that. We exploit rapidly growing productive plants.
But that all presupposes that we can somehow maintain the system in some stable reliable way where all the production is in these lower levels- these smaller fish that are lower down in the food chain. And nobody knows how to do that. You know when we grow wheat or corn, that’s a controlled situation. When a rancher decides to have ten thousand cattle over the next couple of years, that’s a controlled situation. But fishing is hunting and gathering. It’s what we stopped doing on the land thousands of years ago. We just go out in the ocean and we do the equivalent of blowing them away. And that’s not exactly something that you can say, well, this will be stable for ten years or something. We have failed miserably at maintaining fish docks at some stable level so that we can count on exploiting them at some predictable rate. It’s not impossible, but it’s really difficult. We have these ideas like maximum sustainable yield in which we do a whole lot of mathematical calculations and we figure out what’s the production and how much can we take out. And it’s great on paper, but ideas like that assume that there’s no variability in nature. They assume there’re no bad years, there’re no storms, there’re no epidemics. And so that natural variability, with us fishing at some idealized, hopeful, wishful thinking maximum rate, has over and over and over resulted in the depletion of the stock to some much lower level. The history of fisheries is the history of sequential disasters of overfishing.
Interviewer: In addition to a decline in large fish populations, how else are marine ecosystems changing?
JEREMY: From my point of view, there are six different things that are causing the degradation of ocean ecosystems. And fishing is really only one and a half of those six. There’s the pure simple fishing taking out all the fish, the big fish, by hook and line. But one of the most important ways we fish actually is by dragging huge heavy nets across the bottom of the sea floor. It’s called trawling. And trawling is a lot like clear cutting of forests or bulldozing a forest. The destruction of the sea floor from trawling associated with fishing is at least as destructive as the simple direct fishing by hook and line. Essentially we’re turning the sea floor down to five hundred, to a thousand feet, into a parking lot…just a level bottom of what used to be a forest.
Then there’s all these introduced species. Think about the fire ants or the killer bees of the oceans. Think about kudzu vine; it strangles the vegetation of the South; Africanized killer bees that have swept into the United States. All of these incredible pests have economic costs measured in the billions or tens of billions of dollars every year. And you say, well, what does that matter- seen one barnacle, seen them all. But if one of those introduced species doesn’t have any natural enemies and it just grows out and covers everything and kills all the stuff you want, then all of a sudden you care. So introduced species are a big problem. And those are all biological things.
Then there’s the physical/chemical stuff we do that really screws up the ocean as well. We’re warming up the climate that causes things like coral bleaching. The ice is disappearing in the Arctic Ocean. You can pretty much write off polar bears in the next fifty to a hundred years. There’s a remarkable poisoning of the ocean going on. Mercury from all the coal we burn to make electricity, PCB’s… it’s just a long list of stuff which is in all that fish. My daughter, who is twenty years old, asks me is it okay to eat salmon? And, I say, well maybe once a month because it’s full of mercury and it’s full of PCB’s and it’s full of other stuff, which is really not very good from the point of view of a woman who wants to have children someday.
And the worst of all, I think, is the run off of nutrients that are going into the ocean. The miracle of the green revolution, the feeding of all the people of the world from new strains of rice and wheat and corn; we make that happen by using artificial fertilizers. And we use much more than we need to use. And so we dump all this nitrogen and phosphorous onto the land and, it runs into the ocean and, when it gets to the ocean, it fertilizes all the little microscopic plants in the ocean, what we call the plankton. And they grow in huge abundance. The things that eat the plankton can’t keep up. And so the stuff just dies without being eaten and it falls to the bottom. As it rots, it uses up all the oxygen and then there’s no oxygen. All the shrimp die, and the fish die. We call these places dead zones. The dead zone in the Gulf of Mexico is bigger than New Jersey and it’s getting bigger and bigger every year – but it’s not dead. The dead zone is full of bacteria and jellyfish and a lot of the bacteria are toxic. So they make these toxic blooms. As that water drifts into the coastal zone, it kills the fish that wasn’t killed by the oxygen disappearing. It’s pretty disgusting, right? And it’s over a large scale. There are more than a hundred and fifty dead zones in the global ocean. The Baltic Sea is a dead zone. The Wadden Sea off the coast of Germany and Holland is a dead zone. The Northern Adriatic is a dead zone. The Chesapeake Bay. Pamlico Sound- those are all dead zones. A lot of the Northern Gulf of Mexico is a dead zone. San Francisco Bay is a dead zone. And then you go to Asia, Jakarta, Hong Kong, all these places. It’s just remarkable. And so one of the big questions is, will we succeed in dumping so much extra garbage into the ocean this extra fertilizer that we didn’t really need to use, all this nitrogen and phosphorous – that we will turn the entire coastal ocean of the globe into a dead zone.
Interviewer: What are some solutions to overfishing?
One of the options to overfishing is to farm fish. And it’s a good option. There’re a lot of us that are very opposed to the destructive ways that fish are farmed but it doesn’t have to be destructive. I think that’s a battle we’ll win someday, that this activity will become much more responsible. It’s a very important and hopeful thing. Who wants to eat fish that was raised in a sewer? And nobody wants to eat fish that was raised in a dead zone either, especially because of all these toxic bacteria. It would be a kind of gastronomic Russian roulette. Sometimes it would be okay to eat the fish but other times it would kill you. So if we’re going to farm fish, if we’re going to farm oysters and shell fish and fish, we have to farm them in a clean place, just the way we want to farm our wheat and corn in a place that’s not radioactive like Chernobyl or something like that. And dead zones just don’t qualify. It would be really immoral to sell fish and shell fish raised in those kinds of environments. There’s a real economic crisis between all the food we need that’s raised on the land and all the food we need that comes from the ocean. We could solve that problem. We just have to stop being greedy. And we have to be willing to rethink the way we farm. I mean this isn’t exactly rocket science, how to fix some of these things. But from an economic point of view it’s a revolution in the way we live to address these things.
Interviewer: Are oil spills another big contributing cause to marine ecosystem pollution and biodiversity decline?
JEREMY: The issue of pollution is really interesting. Oil spills and human sewage tend to be very localized problems. When they happen on the beach of Santa Barbara with all those wealthy people there and all those wonderful seals and sea lions and birds, it’s a terrible local problem but it’s a local problem. Even the Exxon Valdez, which polluted a huge part of the Alaskan coast, was a local problem. If we wanted to worry about oil pollution, for example, oil spills are not the problem. The problem is all the oil that’s leaked from ships and runs off from the land on a routine basis, which is probably ninety or ninety-five percent of the oil pollution in the ocean: low level chronic stuff that nobody sees except a chemist. But even that is a small problem compared to, say, mercury pollution in the atmosphere, which comes from burning coal to make electricity. It goes up North in the food chains and the Arctic Ocean is polluted with incredible levels of mercury. Pollution is a huge problem.
Interviewer: What is the biggest problem for marine ecosystems?
JEREMY: All of those different issues – fishing and introduced species and warming and pollution – they’re all big problems. What we have to understand is that they all interact with each other. There is no one big problem. If I had to guess for the future, I would say we will solve the fishing problem. The reason we’ll solve it is because oil’s going to become really expensive. It’s not going to make any sense to sail all around the ocean to catch fewer and fewer fish. We’ll shift somehow to some kind of more responsible fish farming. Then fishing will become somewhat less of a problem. Pollution, and the biggest of all, dead zones, will become the really big problem. Everything I’ve been talking about is stuff that we know is happening. The really scary things for the future that one can only speculate about are how is warming and all this extra fertilization of the ocean, how is that changing the way the whole open ocean ecosystem works? Because, the open ocean ecosystem, the stuff way out there, you know, a thousand miles out or five hundred miles out, that’s where an enormous amount of the interaction between the ocean and the atmosphere takes place. We’re only just beginning to understand how the plankton communities and the biological production in the ocean affects the carbon cycle, affects oxygen production, affects the nitrogen cycle. It’s an uncontrolled experiment. And, we don’t really know the outcome.
You should talk to the few real stars in that field, someone like Penny Chisholm who only fifteen years ago discovered an organism called prochlorococcus which is responsible for most of the photosynthesis in the ocean. Nobody knew this creature existed before, because you couldn’t culture it and it was too small to catch on a filter. Tthe only way they discovered it was with genomics. And at that level of ignorance, to be messing around with the organisms that are responsible for the regulation and the modulation of the life support system of humanity is a big risk. People say, yeah, yeah, yeah, we ought to study it for twenty more years. But, I would say that we ought to get our act together pretty soon- because we’re playing with fire. And that is not an exaggeration. I mean, people would never do this if it was something that affected their immediate family. We do this stuff because it’s easy to forget it. And it’s sort of abstract and harder to understand. But it’s out there.
Interviewer: How have human activities threatened marine ecosystems through history? How have things changed over time?
JEREMY: We weren’t so good at polluting in the beginning. There weren’t so many of us. But a few people can kill off an awful lot of wildlife. I don’t think it’s controversial. There are a few people who do still. But, people came to the New World, let’s say around fifteen to twenty thousand years ago, and by ten thousand years ago there were no more mammoths and horses and giant ground sloth- about thirty different kinds of major big animals had disappeared. A lot of the people don’t believe in it and say, oh, it must have been climate. But, you know, we’d had ten big ice ages for a million years beforehand that somehow didn’t do it. And then people showed up, and there weren’t a lot of them to begin with, and all those animals disappeared.
In the beginning of our impact on the oceans, it was mostly fishing- that’s sort of a no brainer. And in the Mediterranean, where civilization began in a big scale of three thousand, four thousand years ago, we wiped out most of the big stuff more than a thousand years ago except for the migrating blue fin tuna which are now almost gone, but which persisted well into the eighteenth, nineteenth century in huge abundance. Similar things in China – the great civilizations of China did a number all the way to Australia on all sorts of creatures. One of the really interesting things about studying things historically is you can see that when Europeans discovered America, then all of a sudden we ratcheted up, with our Western technological efficiency, the rate at which all these things disappeared.
So in the beginning, it was fishing, fishing, and fishing. But, as we became more sophisticated in the way we exploited the environment, we continued to fish, but we also started to do other things that became an equivalently serious problems. I would say that the next really important thing that started to happen was local pollution from human sewage, agricultural run off, and deforestation, which had huge impacts on coastal ecosystems. In the tropics it was massive die offs of coral reefs in areas that were deforested, loss of mangroves, habitat change on the land causing equivalent habitat change indirectly in the ocean was enormous.
There’s a wonderful book called Heartbeats in the Muck, which is a history of New York Harbor. I think it’s a terrific book because in very simple terms it describes what happened to the mouth of the Hudson River and Long Island Sound and that whole area over the last five hundred years. The mouth of the Hudson was one third blocked by an enormous oyster reef that’s no longer there. After all the New York oysters were gone, then they took them from Philadelphia and the Sound. And then they took them from Delaware Bay. Then they took them from Chesapeake Bay. A former student of mine wrote a paper called, “Fishing Down The Coast,” about how the market of New York City drove the sequential extermination of oysters moving North and South from New York City over a period of two hundred years.
So fishing first. But then imagine New York City in 1870, no automobiles. There were as many horses in New York City as they were people. What do horses do? They eat hay. What do horses do? They go to the bathroom. Imagine New York City with a million people and a million horses. Connecticut, New Jersey were hay fields to feed the horses in New York City and Philadelphia. We think of Connecticut today and rural New Jersey, down state New York, the beautiful forests of those regions. They’re only one hundred years old. The automobile was good for conservation of forests in those places because we didn’t have to cut the forest down anymore to grow hay.
All of this stuff was going into the ocean. The low point for New York Harbor was around 1870 when they finally started to try to do something with the sewage and put it in barges and take it out and dump into the ocean. That was the low point for New York Harbor. And, I love this book because it’s very optimistic because, in fact, the water has gotten better and better in New York Harbor. And although, it’s still pretty polluted, it’s being turned around. But that was a very local effect. You could go thirty miles away from New York City and go to beaches that seemed to be pristine and that still had a huge percentage of their original wildlife in them.
It’s the industrial pervasive pollution which is now changing the balance. Atmospheric pollution of all those toxic things, Industrial scale nutrient pollution from agriculture, those forces ratchet up the threats to the oceans a whole order of magnitude. And, surely we are moving into an era where those kinds of pervasive pollution effects are going to become the greatest threat. But, the reason we got where we are today is because we did all that other stuff before.
Interviewer: Can you tell us a bit about the history of the oysters in the Chesapeake Bay?
JEREMY: The Chesapeake Bay is the largest estuary in the United States, and it had billions of oysters. It had all sorts of other fisheries. It had sturgeon fifteen feet long. The first major fishery of Chesapeake Bay in the seventeenth century was caviar shipped to Europe. Just a remarkably productive place. And oysters filter water. They feed by filtering all the little plankton out of the water. It has been calculated because we know how many oysters were there; we know from the industrial economic statistics how many there were that the huge abundance of oysters filtered clean all the water of Chesapeake Bay every two or three days. And they filtered it really clean. Why does the swimming pool get dirty? It gets dirty because we let all sorts of junk run into the pool. Or it gets dirty because the filter breaks. The filter of the Chesapeake Bay was the oysters and a lot of other organisms that filtered the water. We’re polluting the Bay and we’re making it a dead zone because of all the fertilizer. But we’ve been doing that for a couple of hundred years. Maybe not on such a massive scale = the deforestation and agriculture and all of that- but the Bay didn’t get really bad for all that time because the oysters were there to filter the water. So we’ve made it a lot harder to turn things around. We have to stop the pollution. But we also have to make the filter come back. And that filter used to be free. But we don’t have that anymore. Some engineer will come along and say, let’s build artificial oysters.
Interviewer: Has the biodiversity of reef systems declined?
JEREMY: We don’t really know because we know so little of the biodiversity of coral reefs. I mean the answer is certainly yes because of the extraordinary destruction of coral reefs. From the few limited studies that have been made of how many different kinds of worms or how many different kinds of small shrimp-like animals or whatever live in coral reefs, we know that the corals provide homes for all these organisms in the same kinds of ways that trees in a forest provide homes for insects. Places that used to be covered 50, 60 percent by living coral now have 1 or 2 percent, places that used to be complex three-dimensional forests now look like rubble fields, if you go out and you do little surveys, you find much fewer kinds of organism. Have they gone extinct? We don’t know.
But that’s really not the important question. The important question is: How has the functional diversity of reefs changed, whether the species have gone extinct or not? Is it a complex system that works in the kind of way that supports the healthy populations of fish that people want to be able to exploit to a degree? Is it a healthy system that protects the coastline from hurricanes and other severe storms? Does it perform all those kinds of things? There’s no doubt that in that kind of functional diversity sense, coral reefs have been very, very badly impacted in the last 50 years and longer really, but scaling up and speeding up 50 years ago. And then as global warming and disease kicked in about 20, 25 years ago, the rate of destruction was ratcheted up a whole other maybe tenfold.
Interviewer: Can you talk about coral bleaching and coral diseases?
JEREMY: We now have massive events of what we call coral bleaching. The little microbes that live in the corals are plants; they make sugar, they photosynthesize, and they feed the corals the sugar, but when the temperature is too high, they can’t do that anymore. The corals think they’re cheating and kick them out. Then if they don’t get re-infected by those symbiotic microbial organisms, they die of starvation. That’s what we call coral bleaching. In 1998, during an extreme El Nino event that affected the whole Pacific and Indian Ocean, 20 percent of all the corals in the Indian Ocean, as far as we can tell, died of coral bleaching. The Indian Ocean is as big as North America. Imagine if 20 percent of all the trees in North America died because of something that happened on a weekend in terms of climate change. These things are happening on an enormous scale.
There’s a huge argument today about the causes of the increase in epidemic disease. There’s no doubt that we are seeing epidemic outbreaks of disease that kill corals, sponges, lots of different kinds of organisms. Is it because of introduced new pathogens? I don’t believe that. Or is it because somehow or another, we’ve changed the environment in ways that have allowed these things to prosper and grow? That’s what I believe. The one bacteria that everybody, every school child knows is E. coli that lives in our intestines. If we don’t have E. coli, we die. But we can get outbreaks of E. coli that can kill us, too, if somehow or another the E. coli get out of control in our systems. I think that’s more or less what happens in coral reef ecosystems. What we’re seeing is that somehow those cascades in the food chain I was talking about, they don’t just stop at the level of fish and the things fish eat. They clearly affect everything right down to the level of bacteria and viruses. And so more and more what’s emerging is that the imbalance that happens in the populations of microbes and also of seaweeds is causing outbreak of all these diseases. Corals are suffering enormously from overfishing. They’re suffering enormously from outbreaks of disease that kill corals and other organisms. They’re suffering enormously from coral bleaching which is killing massive amounts of corals. They’re suffering from introduced species that overgrow and kill corals. They’re suffering from toxins.
Right here at the mouth of the Panama Canal, 100 years of heavy metal pollution have had huge impacts on corals. They’re suffering from all of these nutrients running off from the land and causing the explosions of plankton, the whole “rise of slime” phenomenon. I believe that the disease is a function of all of those things. It’s a function of the chain reactions in food chains. It’s a function of the introduced species. It’s a function of warming because chemical reactions happen faster when the environment is warmer. And chemical reactions include the metabolism of harmful pathogenic microorganisms. And the dead zone phenomenon happens faster in warmer water. So, all of these things are working together.
Interviewer: What is the first problem that should be solved in order to save coral reefs?
JEREMY: You remember when you were a kid, the nursery rhyme of Humpty Dumpty sat on a wall, and Humpty Dumpty had a great fall and all the king’s horses and king’s men couldn’t put Humpty Dumpty back together again. That’s it. Humpty Dumpty had a big fall. The coastal oceans are a mess and we’re running around trying to figure out how to put this egg back together again. Some people think they’re going to fix it by controlling runoff. Some people think they’re going to fix it by getting rid of disease. And some people think they’re going to fix it by stopping fishing.
The problem is they’ve got to do all those things. The $64,000 question is even if we stop doing them, can we get something back which is sort of like what we used to have? To me as a scientist, but also as a person who likes to eat fish and likes to go to the beach, the really big question is what will the oceans be like in 25 years? Will they be a nice place to go, like this place is still a nice place to go? We drove up here and you guys said, “Wow! This is beautiful.” But you know, I go in the water out here and I cry because the reef is 95 percent dead. To me, it looks like a garbage can. But to somebody who has never seen a beautiful reef before, it still looks sort of nice, you know. Will this still be f nice in 25 years or will it be truly disgusting?
Interviewer: What do you think the oceans will look like 25 years from now?
JEREMY: We had this idea of a movie that we called Escape from Malibu from this shifting baselines project we do to try and make people a little bit more aware of what’s happening in the ocean. The idea was that Malibu, where it costs $5 million for a little wooden shack to live on the ocean, that it would become such a disgusting place that the only people who live there would be the people who couldn’t afford to move to Montana or Wyoming. Everybody laughs when you say that. But, in fact, we found a place in southwest Florida which is already Escape from Malibu.
These toxic blooms happen. There’s a planktonic organism, a dinoflagellate, and it explodes in populations. I have a satellite photograph where you can see the single toxic bloom. The bottom of the picture is Mexico and the top right of the picture is the Mississippi Delta. The entire northwestern Gulf of Mexico is one toxic dinoflagellate bloom. The same species has toxic blooms on the west coast of Florida. This thing comes ashore, this bloom, and it’s very ominous looking. You could make a great movie about it because if you look at it from above, it’s this black cloud in the ocean moving ashore onto the coast. And as it moves ashore, just a little bit of breeze stirs up the water and droplets of the ocean water get into the air. They come ashore and within 24 hours the emergency rooms of all the hospitals fill up with people with acute respiratory distress, asthmatics go into crisis mode. They close the schools. They close businesses. People move away from their dream homes on the gold coast of Florida. It’s Escape from Malibu. It’s the rise of slime. The slime is moving ashore and people have to move away. And that’s not some horror movie. That’s 2006 in western Florida because of all this stuff I’ve been talking about.
So, of course, the big question is will that happen everywhere, or will it only happen in a few places, or will we get smart and figure out how to stop doing that and fix it somehow? You know, it’s sort of simple to say, “Well, we have to stop overfishing. We have to stop turning the seafloor into a parking lot. We have to stop introducing species without even trying to slow it down. We ought to really figure out how to stop global warming at least a little bit, you know, and burn coal in cleaner ways, and use less fertilizer.” What will happen if we do that? Is it too late?
I don’t think it’s too late, but if we magically stop doing that, will it go back to be the way it was before? No, because the world has changed in all sorts of ways. There are 6.5 billion people on the planet. All of this stuff started when there were a quarter of a billion people on the planet. We’re never going to go back. And maybe we don’t even want to go back to the way it used to be. There are these few little places in the ocean where it’s like pure sharks. Well, do we want pure sharks in the Florida Keys? Probably not. But we want to go back at least far enough that it won’t be a dead zone, so it won’t be Escape from Malibu, so there will be nice tasty fish to eat, and we won’t need hepatitis shots to go to the beach. And right now we need hepatitis shots to go to the beach in California. The surfers all get hepatitis shots. We really don’t have much fish left to eat. And we’re living on borrowed time because we’re eating other people’s fish. So will we be able to go to the beach? Will we be able to eat fish? Will we be able to just go swimming? Will we have protection from hurricanes? What will it be like? That’s really hard. There’s a lot of science there. We know it will be better if we stop killing fish, there will be more fish. If we stop dumping too much garbage in the ocean, the ocean will be cleaner. And it will be better. But what exactly it will be like and how well we can manage it to protect the natural biodiversity, and to still have fish to eat, and still have clean beaches to go, that’s a lot harder. And that’s what a lot of us are trying to understand.
Interviewer: Why is fishing a problem for coral reefs?
JEREMY: The reason overfishing is a problem for coral reefs is it’s just a way of disrupting the natural balance in an ecosystem. Ecosystems aren’t perfectly stable. There’s always lots of variability. Hurricanes come and go. But there is a range of natural variability in an ecosystem. And overfishing removes the most important and abundant consumers in a natural ecosystem.
Fish, of course, eat fish, but fish also eat seaweed. And seaweed is important because corals grow very slowly. They build skeletons of calcium carbonate, essentially cement skeletons. And they build those skeletons for the same reason a tree makes wood, to be able to grow up and get to the light because they need the light for the photosynthesis of the little algae in them. They’re all competing with each other and they’re growing up to get there. The hard cement skeleton is a way of doing that. But they also make a skeleton out of cement to protect them from things like parrot fish that come in and just grind them away grazing on them. For everything you invest in one thing, you have less to invest in another. They invest in this structural support and protection. And what they gain in protection they lose in growth rate. Most corals grow only a quarter of an inch to, in most cases, a maximum of an inch a year. Some very fast growing branching corals grow more than a foot a year, but that’s exceptional.
Seaweed doesn’t invest anything in that kind of skeleton. Some seaweeds do a little bit. They have limey cement-like skeletons. Other seaweeds invest in toxins. They make themselves poisonous to protect themselves. But by and large, seaweed grows faster because it invests less in protecting itself. Fish graze the seaweed. Sea urchins do, too. There are all sorts of things, most importantly fishes and sea urchins. that graze down the seaweed. If they’re not there, the seaweed grows ten times faster, 100 times faster than the corals. It grows over the corals, smothers them, and kills them.
Big fish that are predators eat parrot fish. You would think that would be good for corals because it would be killing the things that eat them. But they actually eat more seaweed than they eat coral. So killing the parrot fish might be bad for corals. If there was a population explosion of parrot fish because we ate the big fish, that might be good. But we eat the parrot fish, too. I mean we essentially, in Daniel Pauly’s great phrase, we’ve fished down the food web. We just remove one trophic level after another.
What happened in the Caribbean, what happened right out here on this reef, here was the place where it was discovered that the – you could think of it as the last living lawnmower on Caribbean coral reefs – this black spiny sea urchin were just grinding away eating the algae. Then in 1983, starting right here, there was this epidemic disease explosion that started to kill the sea urchins. Within one year, 95, 98 percent of this species of sea urchin were killed throughout the Caribbean, from Florida to Panama, to Barbados, to Cuba and Puerto Rico, all of it. I was in Jamaica at the time it hit Jamaica. Within a week, the coral reefs looked like they needed a shave. There was this fuzzy green stuff that was growing over everything. A guy named Terry Hughes, who was a Ph.D. student of mine who did some really elegant work on population dynamics of corals, he was there, he saw it, he was ready for it. He documented the changes that happened after this last important grazing animal effectively disappeared. Within a year, seaweed covered the reefs. The corals went from 50 percent living cover of corals to only a few percent living cover of corals. There was all this seaweed covering over everything. That’s why overfishing is bad for coral reefs.
The last straw was the sea urchin. The reason it’s complicated is because there’s also a balance of power. Just the way there’s a balance of power between corals and seaweeds, there’s also a balance of power between different kinds of predatory fish, and grazing fish, and grazing sea urchins. We have a couple of students at Scripps who have gone around looking at the condition of coral reefs throughout the northern Caribbean. They’ve looked at reefs in about 35 places. And among those places there are a lot of places that have been protected from fishing for more than ten years over really big areas, at least 100 square kilometers–so that’s something on the order of 25, 30 square miles. Some of these places are even bigger. There’s a place on the south coast of Cuba where for almost 100 miles it’s completely protected. And in those places, surprise, surprise, you don’t kill the fish; the fish come back. There’s lots of fish and lots of big fish. What’s really important is even though it’s very complicated and we don’t understand all the details, in those places where there’s lots of fish, there’s been a huge reduction in the seaweed. The corals haven’t come back yet because the corals grow slowly, remember. And so it’s going to take a long time for corals to come back. And, of course, there are all sorts of other problems that corals have. But at least half of that story, the elimination of the large amounts of seaweed, has been now shown effectively experimentally through the mechanism of these protected areas.
In the central Pacific, in the Line Islands, we did an expedition there, a whole bunch of scientists from Scripps and lots of other places. We went to four islands that ranged from having 10,000 people on them to no people. With all that gradient in people, there were a lot of things going on, pollution, not just fishing. But in the place with no people and no fishing – imagine you go to a place and you get in the water and practically all you see is sharks. Eighty-five percent of all the weight, what we call biomass of fish, in this place called Kingman Reef, which is a thousand miles south of Hawaii, 85 percent of the weight was sharks and big huge fish that eat other fish. Going to this reef was like getting in a time machine and going back 100 or 200 years in time. There was no seaweed on those reefs. The reef was really pink, which is healthy, because it’s the kind of cement-like — we call them coral and algae that the coral larvae like to settle on. There was lots of coral recruitment on these reefs. That reef system was healthy even though ten years before there had been a massive bleaching event that had killed off most of the branching rapidly growing corals. But the reef was recovering because the system was healthy, and recruitment was high, and disease is low. All of this is integrated and tied together, and fishing is a big part of that story.
Interviewer: What is the “rise of slime” and what causes it?
JEREMY: What I call the rise of slime is properly called eutrophication, the introduction of excessive amounts of nutrients that allow the microscopic plants in the water column, and also the seaweeds on the bottom, to grow at extraordinarily rapid rates. Normally, in a healthier ecosystem, they’re limited by the amount of nutrient that is available. Just as we put fertilizer in a field to get more corn or wheat, because otherwise we’d get a lot less corn, there’s a lot less production of these microscopic plants and of seaweeds on the bottom when there’s very low nutrient levels.
The introduction of a certain amount of nutrient can be a good thing because the productivity increases. When people want to farm fish, they want to give more feed to speed things up. But it can become a runaway process. It can get out of control. If it gets out of control, there’s far more nutrients than can possibly be used. There are far more microscopic plants and seaweed than the grazers can possibly eat. The stuff just builds up and builds up. It dies before anything eats it. It falls to the bottom. It rots. The process of rotting consumes all the oxygen. We breathe in oxygen and we breathe out carbon dioxide. We use the oxygen for our metabolism. Fish use oxygen for their metabolism. Shrimps use oxygen for their metabolism. So all the animals that normally would be using that oxygen die because this rotting of all this excess vegetation consumes all the oxygen. So there’s no shrimp. There’s no fish. And all you’ve got is jellyfish at the surface and all these microbes and there’s nothing really to graze them except the jellyfish. The whole system kicks into a different kind of producers, which is essentially microbes that don’t feed the zooplankton, that don’t feed the sardines, that don’t feed the fish we want to eat.
A dead zone is not dead, it’s incredibly alive, but it’s an ecosystem, which lacks all the kinds of animals we want, and has all the kinds of animals we don’t want, and has all these toxic microbes. Slime is a graphic way of describing a huge overabundance of all the things we don’t want, the microbes, the bacteria we don’t want. And it’s not just dead zones. The rise of slime is also disease, the excess nutrients, the excess production that fuels the wrong kinds of microbes that kill the organisms we want like corals and fish.
Ecologists talk about things that are bottom up. Bottom up means processes that are limited by the input of nutrients that allows production to occur. The ther term is top down, the predators and herbivores that control the system from above. In reality, ecosystems work in both ways. They are controlled from the bottom up by the levels of production, and they’re controlled from the top down by the control of the food chains by the consumers. A healthy ecosystem has a balance that we understand between these different top down and bottom up processes. Dead zones happen, the rise of slime happens, when we destroy that balance.
Interviewer: If biodiversity decline continues at current rates, what’s going to be left?
JEREMY: What will be left in the oceans is a lot of bacteria and a lot of jellyfish. I think about that a lot. I sometimes ask my students, “Write a paper. Who will be the rats and the cockroaches of the oceans?” – because the oceans won’t be completely dead. In my apartment in Panama City, there’s probably 100 species of animals, of different ants, and lizards, and birds that nest on the balcony, and beetles, and the occasional scorpion, and lots of different kinds of spiders. There are animals and plants that love people. Right? And rats and cockroaches are two of our least favorite symbionts. They’re symbionts with us, whether we like it or not. The question that really interests me is what will be the organisms that benefit from us? Obviously bacteria, and not very nice ones: obviously disease organisms; obviously jellyfish that clog our fishnets. We have fisheries of jellyfish now in places where there aren’t any more fish. In the dead zones, they actually fish for jellyfish and sell them to southeast Asia where people eat them. But there will be a lot of other things. Maybe some of it we’ll like. Who knows? From a scientific point of view, it’s a very cool, fascinating, fun question. But the odds are certainly that we won’t like the outcome if the creatures that will take over will be the creatures we didn’t really want to have there.
Interviewer: Given the current state of the environment, what do you see looking forward?
JEREMY: I’m pretty pessimistic. I think that there’s no doubt we’re going to see vastly more destruction. The big question is whether or not we’ll wake up to the magnitude of the threat. I have this view of how it all works – that humanity and civilization are like a bunch of people living in a castle. The walls of the castle are what we call technology. We achieve a way of life that we like and that has allowed us to prosper, and to live longer, and be healthier, and have art, and music, and all these good, cool things because of the benefits of that technology and that way of life. Nature is the thing outside the walls. People have always been mostly afraid of nature. It’s not until the advent of romanticism that we started to talk about nature as good thing. Before that, it’s kill the bears, and the wolves, and the tigers, and the lions that are bad news, and cut down the forest, which is a fearful place. Think Hansel and Gretel and all those terrifying stories that they used to read to children about nature is this dangerous place. And, of course, nature is also the place that we throw all our garbage out. It’s really interesting because economists have a name for the garbage. They call the garbage externalities and it’s all the stuff that we didn’t pay for, for what we call progress, which is all the good that we enjoy in our civilization inside the wall.
The problem is that the externalities, the garbage, is knocking down the wall. We can no longer write it off and ignore it. To me, the big question is how fast will we learn that this is happening because whenever something goes wrong, we want to fix it with another technological marvel, but that’s not going to do it. Technology is a wonderful thing and it will help us in all sorts of ways. But at the end of the day, the real problem is how we change the way we live. If we do that, then we won’t have an apocalypse. And humanity will continue. The question is when my new little granddaughter is 30 years old and thinking maybe about having children, will she want to have children? Will the world be a kind of place that she would want to bring another human being into? And what will the quality of life for my kids and my grandchildren be like? Because we’re not going to go extinct, I don’t think. Even avian influenza, if it happens, even if it kills a quarter of humanity, I don’t see us going extinct. But I can see a pretty horrible world.
I re-read The Time Machine by H.G. Wells last month. I hadn’t realized what a brilliant book it was. Because as he moves into the future, the first place he stops, there’s no wild animals left for people to eat. As he moves even further into the future, there are no people left; there’s nothing left but crabs and slime. H.G. Wells figured it out when he wrote that book, which was a potboiler, it was a best seller. He predicted it. He predicted a very gloomy world. And he was not an idiot. He was a very, very smart dude. Everybody ought to read The Time Machine. Of course, they won’t take it seriously. Oh, it’s a fantasy. But there was enormous wisdom in that book because if the world becomes a world of slime, then there’s not much room for people.
Interviewer: Can you tell us how you became interested in studying marine ecology?
JEREMY: I’m the only scientist in my family. I grew up in a family of writers, and historians, and artists. But my father was really interested in science for fun. He read a lot of physics and he read these popular books written by people like Einstein. I started reading those and I loved them. I wanted to be a physicist. And then when Sputnik went up, I wanted to be a physicist in relation to those kinds of things. Then I went to college and I discovered I was a pretty mediocre physicist. But, that was probably a really good thing because all that time my father was actually an historian and I loved history. And by accident really I became interested in historical sciences. I became interested in human evolution, anthropology, paleontology, and ecology. And what I do now, I’m really an historian who studies the history of nature for the last 25 million years or so.
When I became involved in conservation, it was because as a person in my fifties, I began to realize that all these places I had studied were really different from the way they’d been when I first started studying them, in some cases tragically so. The coral reefs of Jamaica that had been among the most beautiful reefs in the world were just covered with rotting seaweed and it was disgusting. I got really interested in how did this come to be. And it was a no-brainer that it was due to people. But to ask more subtle questions about what we do and how we do it that causes these problems. That was really interesting. So I started to delve back.
In one of these wonderful accidents of fate, my father had been a maritime historian and his specialty had been the maritime history of the Caribbean. I had worked on reefs in the Caribbean. As a kid he had read me all these stories about these English pirates in Jamaica and their descriptions of what the Caribbean was like when Columbus came or later on. So I delved into that. And, the real turning point in my life and sort of my second career as a historical ecologist was when I gave a talk to more than 1,000 coral reef biologists here in Panama when we hosted the International Coral Reef Society meetings. The talk was called ‘Reef Since Columbus.’ It was a reconstruction of what it was like here when Columbus came. After that talk to a thousand people, you could hear a pin drop because basically what I told them was they didn’t have a clue of what a real coral reef had been like. And I had managed to make it graphic enough that they couldn’t go into total denial and they had to come to grips with it. This was in the old days of color slides and no PowerPoint. I had said, “Don’t you ever use the word pristine again.” There were people who had gone around and taken pens and crossed out the word pristine on their color slides because they were embarrassed to use the word pristine. And one thing led to another.
9.1 Biodiversity Decline Video
Species are being lost at a rapid rate in rainforests and coral reefs. Yet many species still have not been discovered. Tropical scientists struggle to keep ahead of the bulldozers as they work to understand this complex ecosystem. And an ocean biologist predicts the death of life and the "rise of slime" in the sea. How can we protect the biodiversity of these vulnerable ecosystems?
Unit 1 Many Planets, One Earth
Astronomers have discovered dozens of planets orbiting other stars, and space probes have explored many parts of our solar system, but so far scientists have only discovered one place in the universe where conditions are suitable for complex life forms: Earth. In this unit, examine the unique characteristics that make our planet habitable and learn how these conditions were created.
unit 2 Atmosphere
The atmosphere is what makes the Earth habitable. Heat-trapping gases allow ecosystems to flourish. While the NOAA Global Monitoring Project documents the fluctuations in greenhouse gases worldwide, MIT's Kerry Emanuel looks at the role of hurricanes in regulating global climate.
Unit 3 Oceans
Oceans cover three-quarters of the Earth's surface, but many parts of the deep oceans have yet to be explored. Learn about the large-scale ocean circulation patterns that help to regulate temperatures and weather patterns on land, and the microscopic marine organisms that form the base of marine food webs.
Unit 4 Ecosystems
Why are there so many living organisms on Earth, and so many different species? How do the characteristics of the nonliving environment, such as soil quality and water salinity, help determine which organisms thrive in particular areas? These questions are central to the study of ecosystems—communities of living organisms in particular places and the chemical and physical factors that influence them. Learn how scientists study ecosystems to predict how they may change over time and respond to human impacts.
Unit 5 Human Population Dynamics
What factors influence human population growth trends most strongly, and how does population growth or decline impact the environment? Does urbanization threaten our quality of life or offer a pathway to better living conditions? What are the social implications of an aging world population? Discover how demographers approach these questions through the study of human population dynamics.
Unit 6 Risk, Exposure, and Health
We are exposed to numerous chemicals every day from environmental sources such as air and water pollution, pesticides, cleaning products, and food additives. Some of these chemicals are threats to human health, but tracing exposures and determining what levels of risk they pose is a painstaking process. How do harmful substances enter the body, and how do they damage cells? Learn how dangers are assessed, what kind of regulations we use to reduce exposures, and how we manage associated human health risks.
Unit 7 Agriculture
Demographers project that Earth's population will peak during the 21st century at approximately ten billion people. But the amount of new cultivable land that can be brought under production is limited. In many nations, the need to feed a growing population is spurring an intensification of agriculture—finding ways to grow higher yields of food, fuel, and fiber from a given amount of land, water, and labor. This unit describes the physical and environmental factors that limit crop growth and discusses ways of minimizing agriculture's extensive environmental impacts.
unit 8 Water Resources
Earth's water resources, including rivers, lakes, oceans, and underground aquifers, are under stress in many regions. Humans need water for drinking, sanitation, agriculture, and industry; and contaminated water can spread illnesses and disease vectors, so clean water is both an environmental and a public health issue. In this unit, learn how water is distributed around the globe; how it cycles among the oceans, atmosphere, and land; and how human activities are affecting our finite supply of usable water.
unit 9 Biodiversity Decline
Living species on Earth may number anywhere from 5 million to 50 million or more. Although we have yet to identify and describe most of these life forms, we know that many are endangered today by development, pollution, over-harvesting, and other threats. Earth has experienced mass extinctions in the past due to natural causes, but the factors reducing biodiversity today increasingly stem from human activities. In this unit we see how scientists measure biodiversity, how it benefits our species, and what trends might cause Earth's next mass extinction.
unit 10 Energy Challenges
Global energy use increases by the day. Polluting the atmosphere with ever more carbon dioxide is not a viable solution for our future energy needs. Can new technologies such as carbon sequestration and ethanol production help provide the energy we need without pushing the concentrations of CO2 to dangerous levels?
Unit 11 Atmospheric Pollution
Many forms of atmospheric pollution affect human health and the environment at levels from local to global. These contaminants are emitted from diverse sources, and some of them react together to form new compounds in the air. Industrialized nations have made important progress toward controlling some pollutants in recent decades, but air quality is much worse in many developing countries, and global circulation patterns can transport some types of pollution rapidly around the world. In this unit, discover the basic chemistry of atmospheric pollution and learn which human activities have the greatest impacts on air quality.
Unit 12 Earth’s Changing Climate
Earth's climate is a sensitive system that is subject to dramatic shifts over varying time scales. Today human activities are altering the climate system by increasing concentrations of heat-trapping greenhouse gases in the atmosphere, which raises global temperatures. In this unit, examine the science behind global climate change and explore its potential impacts on natural ecosystems and human societies.
Unit 13 Looking Forward: Our Global Experiment
Emerging technologies offer potential solutions to environmental problems. Over the long-term, human ingenuity may ensure the survival not only of our own species but of the complex ecosystems that enhance the quality of human life. In this unit, examine the wide range of efforts now underway to mitigate the worst effects of man-made environmental change, looking toward those that will have a positive impact on the future of our habitable planet.