Global Problems of Population Growth

MCDB 150 - Lecture 24 - Population and the Environment

Chapter 1. Course Retrospective [00:00:00]

Professor Robert Wyman: [Video clip] Well I think you got the message. I was actually going to show you--this is the end of the course. Let me show you--[at] the beginning of the course a little video, but it was not in the right format. It shows our favorite dung beetles copulating. It's very graphic and it looks just like humans, the same rhythm and everything, same motions. The message of the course was, this is what this course has been about: start with insects doing their thing and you end up with humans doing their thing, and in between nothing really has changed.

The desire to engage in sex has not changed, the quest for status which determines [access to] sex. We've had this over and over again in the course and I hope you realize by now that we've discussed so much from the Princeton project and other projects [about] how much social acceptance is an important part of fertility. That people determine their own fertility a lot because of what is the acceptable norm in the community. Aside from the direct status of having a lot of sons, a big family gives you big status, because of protection and political power from the large family and economic security. But it's all tied in with status.

I think I mentioned to you that, for instance in Bangladesh, they looked at fertility as a function of religiosity and one factor that had some effect was the religiosity of the particular family, but the much bigger effect was the religiosity of the community. It's all community acceptance. It's all status and we just--that comes directly from the chimpanzees. Of course you're aware that a vast percentage of human consumption, and the richer you get the greater it is, is status consumption. The only difference between a Mercedes and a Ford is basically status and that kind of thing.

You've also seen that between groups, the hostility between groups has not--basically not changed since chimpanzees. The maltreatment of females, the battering of females among chimpanzees, the battering of females among humans, it's all stayed about the same. I could have shown you that video, you would have gotten the message that--and also why this is a biology course, or at least part of the reason, is because the fundaments of almost everything that we've talked about are the same set of behavioral propensities that are apparently wired into us in some way since our chimpanzee days.

This last--this video that you did see, the main point is that the situation we are in now with respect to population is totally unprecedented in the history of humanity, there's just never been anything like it. You also know something about the future--

Student: Professor Wyman, what year was that video made?

Professor Robert Wyman: What?

Student: What year was that video made?

Professor Robert Wyman: That video was made in--I wrote that down--I think 1990 and the projections--the actual numbers are pretty good for their projection. This is not a new video and I'll show you the situation.

Chapter 2. Population Projections [00:10:26]

What's usually--these are the projections that the UN has put up for the future of population. I think I showed you--early in the course when I was discussing quantitative methods, the US Census Bureau projection and that more or less mimics this one. The UN shows you that there's a range, they do not know what's going to happen, and so they give you a range of possibilities for the future and they do not call them predictions at all, they are simply projections. Meaning that if X, Y, Z, P or Q happens then this will be the course of population but they don't say which of these things is going to happen, if any of them.

What would you consider in terms of say fertility? What would you consider the most conservative projection? We know what's happened in the past, we know what the status is today, how should we make our future projection, fertility staying the same, fertility going up, fertility going down?

Student: Going down.

Professor Robert Wyman: Thinks down, okay. The UN, that's one of the projections. To my mind, the most conservative projection is that whatever we're at today that's where we continue to be at. In the sense, that's what I think conservative means that you preserve what's been in the past. Well that's this projection that the fertility that the world is at today continues just as it is.

The projection that's carried out to 2050, and assuming that [fertility] stays where it is, it will be--the population will be 12 billion. We're now about 6.7 billion. The population will be not quite double what we are now, and [will be] rising ever faster. That's the status quo assumption. The other assumptions are optimistic that things will--that fertility will come down. They're not unreasonable assumptions and the reason why some of you chose fertility coming down because fertility has been coming down.

It's not a crazy presumption, but how much is [fertility] going to come down? The UN gives you three possibilities. This projection, which they call the high projection, assumes that fertility will come down another half of a child. Right now this was based on the average fertility between 2000 and 2005, it was about 2.8 children, 2.85 children, and they're presuming in this projection that it'll come down another half a child for every--the average for everyone on earth to 2.35, still above replacement level fertility. With that degree of optimism, fertility comes down another half a child, population keeps increasing, not as fast as this, and by 2050 we get to roughly 11 billion and it's pretty much going up in a straight line.

Now you can get a little bit more optimistic and say, well it's going to come down a whole child's worth, and that's this scenario here. Now we're at 1.85, the whole world has come down to a quarter--replacement level fertility, as you know, is 2.1 children, so 1.85 is a quarter child below replacement fertility. You can decide for yourself how much optimism is involved in assuming that's going to happen. If that's the case, then population is like nine billion in 2050, and continuing up, but clearly beginning to level off at that time. Now they get really optimistic and they do this line. And that's--[fertility] drops a child and a half in this short amount of time and goes down to 1.35 children, way below replacement fertility, and that's for the whole world.

The assumptions are--these are the UNs own statement of its assumptions. The constant fertility one, fertility remains constant at an average of more or less 2.8 or 2.85. The high fertility assumption: they're calling a reduction from the [current] fertility to 2.35 children. Medium: 1.85. 1.35. And then they have a really miraculous assumption, the instant replacement assumption, which they don't bother to graph, which is each country, immediately, like tomorrow, comes down to just the birthrate that will replace its population, no more and no less.

What should we notice about these things? Obviously they're pretty arbitrary assumptions. No one knows what's going to happen in the future. No one claims to know what's going to happen in the future and it's a sign that we don't--we just don't know enough about this issue. I mean I've told you a lot of--the basic stuff that's known. We do not know enough to really predict.

We asked, at the beginning of the course, the middle and the end of the course, why has fertility been coming down? What are the determinants of fertility? You've gotten a whole lot of answers. If we knew the answer for sure we would be able to predict, but the future is not terribly predictable. These are projections not predictions. We've got a huge range there from about eight billion to about 12 billion, that's an uncertainty, and in the not terribly distant future, of 50%. That's a very large degree of uncertainty.

Only the most optimistic assumption, this last one, only the most optimistic projection has population decreasing by 2050. All the other assumptions show it continuing to increase right through 2050 with no statement about what might or might not happen beyond that. In the medium variant, this is the one that they call the medium variant, and because they use that word, 'medium' the press sort of takes this as, well, the most likely or something. The UN does not say anything about the likelihood of any of these estimates, but take your choice.

In this rise that we're now increasing at, from 1970-up to 2007 [now], the average rise was about 78 million a year. In this scenario by 2050 it's--the population is still increasing by 30 million a year, so that's their medium variant as far out as they're willing to even project, not predict, but even to project, population is still increasing by 30 million a year. I keep saying these are optimistic, remember none of these assume that fertility starts rising again.

We have indeed had a fall in fertility. And there are certainly reasons to believe that if the world--we've had a fall in fertility and we've also had really rather great progress in the world, say since the end of World War II. I mean people are staying alive, they're getting more educated, all parts of the world China, India, Indonesia, are just unbelievably richer than they used to be, although still very poor and pockets of real poverty exist. I mean most of the world has just improved tremendously, both in the rich countries in the West, Japan and in the poor countries.

If you had to choose a date that you would like to be alive, but you couldn't choose who you would be or where you would be, the only reasonable date to choose is now. Because the average human being on earth was worse, worse, worse going back as far as you want. Now, if you could choose to be a rich person, that's maybe another story. But if you just would be randomly set down anywhere, you would choose to be now. So things have been getting better, there's no question about it.

If things continue to get better--it's very reasonable to presume that one of these, maybe not this curve but one of these more optimistic curves might take place. There are a lot of reasons why things may not continue to get better. In the paper that [I assigned]--segments of a paper that I wrote, I list a number of them.

Chapter 3. Factors Affecting Future Population [00:19:54]

One that I listed there was an economic collapse, and I was talking about the fairly small economic collapse in Asia in 1997 which had just happened at about that time. I did not envision, as did no one, we have really now a global kind of mega-crash and will we recover or not, who knows. If economic progress is one of the things that's required or economic increase is one of things that's required for population to keep coming down, then the global economy - who knows what's going to happen. It may very well turn around.

Religious fundamentalism is another thing that we know. It's not a particular religion Christianity, or Islam, or Judaism that matters, but it is the religiosity, the degree to which people are religious in whatever their religious tradition is. That latter makes a difference. Religious fundamentalism is basically increasing all across the world, including the United States, of course. I read an article that, Notre Dame is one of the great Catholic Universities in America and the priests, a number of the priests--of the order that founded Notre Dame and still run it, didn't want--President Obama was invited to be the speaker at graduation this year and the priests didn't want him to be because he's pro-abortion.

The conservatism in--at one end of the spectrum of all religions is there and increasing. You see the Taliban is at one end of the Islamic spectrum, they are powerful--increasingly powerful not only in Afghanistan but now in Pakistan. I don't know if you've been reading the newspapers, but they have now taken a provincial big city or capital, it was only like 13--30 miles or something from Islamabad, the capital of Pakistan so they're increasing.

The population of Orthodox Jews in Israel, because they reproduce so much faster than everyone else, is very close to overtaking the population of more moderate Jews. The Palestinians and the Orthodox Jews in Israel are having a battle to see who can increase their fertility fast enough to sort of out-reproduce the other.

Another factor is the decline in support for international family programs. As you're undoubtedly aware, the population explosion which was a very hot issue for the press and for all kinds of activist organizations in the 1960s and 1970s has just fallen off the map. Our own school of Environmental Studies here, Forestry. does not have a single person that pays any attention to human population. Courses like this are taught basically nowhere else, very few places elsewhere.

Environmental organizations won't go near the population issue and so government is not under any pressure from the citizens are reducing their support of family planning. This has already happened in large degree, as well as a lot of other good programs, and with the economic problems of all governments now it's going to fall even further.

Student: Don't economic problems exacerbate social problems that governments would want to control their fertility?

Professor Robert Wyman: Very good statement, so do economic problems exacerbate social problems so that people will want to more control their fertility?

Student: Or the government has a much more vested interest to control fertility.

Professor Robert Wyman: What you say is reasonable, but the opposite of everything that we've sort of said in the course. When things are getting better, that when people come from being--except for land availability that--when infant mortality goes down people reduce their birthrate. When education is available people reduce their birthrate. When countries get richer people reduce their birthrate. So, No. it's exactly the opposite of--you should definitely take that away from this course - that good things happen when things are already getting better.

The reduction in fertility goes along with, I didn't say caused, but goes along with an improvement in every kind of condition that you can count. When the economy goes--in the 1997 Asian crisis, a lot of women working in the cities and were working at factories at sewing and so forth, not having children. They lost their jobs, they went back to the villages and guess what they did? They started having children. It's improvement in a situation that gets fertility down.

Student: To go along with that question, maybe because it's more of a short-term economic decline it's more of a shock and more of a depression that might cause people to temporarily reduce--

Professor Robert Wyman: Okay excellent, her question was, because this is a short term, more of an economic shock than a depression, maybe people will temporarily reduce their fertility. That's a wonderful observation. Economists really don't know how to answer that. When I started teaching this course I taught--co-taught it with a professor of Economics and he was teaching sort of the economic determinism, This is really what he believed. He thought that, as countries come up economically, fertility will come down more or less automatically. He was of the mind that development is the best contraceptive. I've shown you--since then the data has shown, I think clearly shown, that's not the case but that was his belief then.

Then comes this 1997 economic collapse in Asia and I go up to this professor, who I was not teaching with anymore, and I say--I say to him 'gee here's this economic collapse in Asia, what do you think will happen?' He said to me, 'I think fertility will go down, which is what you're saying because conditions are getting worse,' and what you're saying. I was shocked and I said, 'but, and I won't tell you his name, but that's exactly the opposite of what you taught in the course.' What he said to me was, 'I think the theory is flexible enough to accommodate both results,' which means the theory didn't predict anything. If you can predict this and then the opposite it doesn't predict anything.

So we don't know that answer to this. I mean, first of all, we don't know if this is a temporary economic collapse. I mean we hope it is, but no guarantees. The data to figure out the difference between what's short term, which is undefined, and what's long term, which is undefined, very difficult to do; you may be right you may be wrong. I think we just can't be certain about that.

Of course, the other factor which could cause things to go to hell in a hand basket is environmental collapse. As the environment gets bad, if things start getting used up, if people really start starving or lose--not having water or whatever the environment will do first, and we'll talk maybe a little bit about what might happen first. Then, again, things could go backwards very, very fast. None of this is--are predictions that I'm saying.

I'm just saying that here's all this optimism, all of these except the top--the constant one, all of those are optimistic presumptions that may take place. But there's just as many reasons to think that, no, things will turn around and fertility will go back up. We just don't know the future. We CAN say that, by almost any kind of reasonable assumption, for the next 40 years at least, we're in for a very significant increase in population that is going to happen.

Chapter 4. Population and Environmental Impact [00:28:13]

How does one--trying to make this lecture at least somewhat about the environment. How does one relate this population increase to environmental destruction to decay of the environment? This is not an easy question. There's so many variables between human population and environmental destruction that it's hard to pick out what's just due to the population.

The simplest statement that you can make is that the total human environmental footprint, footprint is an idea come up by I guess some en--I don't know. Is there a name attached to who came up with the use of the word footprint? Anyway, the idea of the total environmental impact of an individual, a city, a country, an industry, whatever, the environmental footprint is what's said. In the simplest way of thinking about it, the environmental footprint is proportionate to the number of people. Each of the people on earth have an average footprint, the more people, the bigger the footprint. And that holds at any level, any assumptions you want to put on it. More people, bigger footprint, so that's fairly obvious.

It doesn't tell you an awful lot and so, many years ago, a guy named John Holdren proposed a sort of expansion of that idea and he is now Obama's--the Director of the Office of Science and Technology, just recently appointed by President Obama. So, at least now, you have someone in power who thinks about population. What he came up with was this equation, the impact, the environmental impact, he breaks it down and he says you don't have to worry only about population but how rich is that population, there's a difference between rich people and poor people. What about the technology involved?

Affluence is that we clearly know that rich people consume a lot more than poor people, between the poorest groups on earth and the richest there's a factor of something like 40 depending on how poor you want to go and how rich you want to go. That number can be almost anything, but 40 is a reasonable number to keep in mind, so affluence is certainly important. The amount of money your population has. And technology, so nowadays if we want to knock down a forest we use bulldozers and chainsaws, chainsaws that will cut down a 40 foot tree with one swipe. Clearly that technology allows you to have a much greater impact than if you're going out there with a little hand hatchet, or maybe even a stone ax to try to chop down your tree. The amount of technology that one has clearly makes a tremendous difference on how much destruction you can do.

What you should notice is that like all--so this is symbolized by IPAT, the impact is population, affluence, technology all multiplied together. You should keep in mind that this is a tautology. Tautology means something which is always true, the equation is always true, and you just see that from--you define population just people, affluence is the income per person, the number of dollars that person has, and technology is defined in this nice way of the impact per dollar spent.

That's the--how you're defining these terms, how you're measuring these terms, and you'll just notice that if you cross multiply the persons and persons cancel out, the dollars and dollars cancel out, so your equation ends up that the impact is equal to the impact. That's the sign of a true equation, true of hitting all--it's a tautology, it's always the case.

I should show you that, for instance, this is a standard thing out of Science magazine, one of their stories about population. What are they doing: impact, here's the first thing, they list impact per dollar. In this case, the impact they're interested in is carbon. So, they're talking about the carbon budget, they even use the word budget for that and it's for each US dollar.--This is a global figure they're going to give, you but they're calculating it in US dollars. For each dollar spent on something in the world how much carbon is used? So that's kilograms of carbon per dollar and it's about now about a quarter and it's changed somewhat over time but not enormously, so it's gotten better. This is--the lower the number the better that for each dollar of stuff that you buy there's basically less carbon used to make it. This kind of way of thinking about environmental impacts is now actually rather standard and you really can't avoid this kind of thinking.

One of the real important things about this, that people make mistakes on all the time, is that the factors multiply. That you don't add the population plus the affluence, plus the technology, you multiply them. One of the--there's a very important book, I think it's called Something New Under The Sun, and the guy who wrote it, Yale tried to hire him as our environmental historian. He was adding these factors and making all kinds of totally wrong conclusions, saying that, well the rate of growth of affluence is so much and the rate of growth of population is so much, so this one is more important than that one; just saying utter nonsense because he didn't realize the importance of the fact that--anything per capita is multiplied by the total population to get your global impact.

The global impact is something, you're interested in the total impact, the total amount of carbon dioxide, you're not interested so much in how much carbon dioxide I put into the air but how much the six, seven billion of us put into the air.

Now the equation looks simple and it's always true, and yet it's not as straightforward as one would like, because people take something beyond the tautological fact of it being true. What this--as I've described it, what this makes you think is, well, an increase in population is always bad, it always increases the impact, an increase of affluence is always bad, it always increases the impact, and improvement in technology is always bad, it increases the impact. That's not true.

As people get richer, as affluence goes up, they tend to spend a somewhat larger fraction of their income on environmental issues. That once you have a nice house and a nice car, and nice school, and nice clothing you may actually want to breathe nice air, and look at something green and have a park to go walk into. So rich people do indeed spend more than poor people on environmental issues, so affluence can work both ways and that's very important to remember.

However you have to step back a little bit and say, well in the world what fraction of our increasing affluence have we actually spent on the environment? We have spent a very small fraction of it, so in fact, the overwhelming, dominant effect of our affluence has indeed been to have a greater impact on the environment and we've ameliorated that a little bit. I mean very noticeable, the rivers in America, we are a rich place, rivers are really--a lot of rivers have been cleaned up, a lot of smog has been cleaned up, so we have made progress in certain very visible ways.

We've exported a fair amount of our environmental concerns to other parts of the world by having them manufacture stuff and bringing it in here, and knocking down their forests to bring in wood and so forth, and the Chinese and the Japanese have done just the same kind of thing.

Similarly, with technology, it doesn't always work one way. Yes, technology allows you to blow off a mountain top to get some coal. You've seen these horrific pictures of West Virginia and so forth where a more or less beautiful mountain that's covered in trees is just gone, and all that mountain top becomes slag and pollutes rivers and acidifies rivers and does horrible things, and you have this ugly, scarred-up land, so technology does that.

But also improvement of technology. Begins with the mining of copper; when you replace copper wires with fiber optics, they're made of glass and glass is made from sand and the harvesting of sand doesn't do an awful lot of environmental destruction. So, that's an improvement in the environment and there's a number of examples of that. Again you have to ask--cars are--our current push now to make cars that use less gas. So the good that it does use, it gets you how many--to drive a mile you use less gas, not enormously less, but somewhat less.

Technology can help you, and again the standard question is, has our improvement in technology over the last 20, 30, 40, 50 years, whatever time window you want to deal with, has this allowed us to do more environmental destruction of the earth or have we used enough--a big enough fraction of it to improve the environment. Our efficiency of use of the environment, that the things have gotten better and the answer is: there's no question about what's happened.

You see in this, again this is more CO2 stuff, that here is the sources of CO2 addition into the air, which is a very good index of what's happening in the total economy. What you see is the land use, so land adds into the CO2 by--where deforestation and using wood for timber and everything. The amount--the land use, the changes in land use has not enormously changed.

The width of that line is more or less the same over time, so the change in land use is putting about the same amount of carbon into the air as before. There's a little bit of other emissions which we don't have to worry about, but fossil fuel combustion has just gone up, up, up, and up. Whatever the balance of our affluence and our technology, whatever the balance, well we can see that is the balance of our use between using it to ameliorate the environment versus messing up the environment and we'll come back to this slide if we have a chance.

The--in terms of the efficiency, that first factor, not the first factor, the dollars per carbon use that is here. Actually the carbon use per dollar is quite interesting; it has been coming down. From 1970 it was about a third of a kilogram of carbon per dollar and that's come down to now something like a quarter of a kilogram per dollar spent, and that's just carbon, so you multiply that by almost four if you want to measure in CO2 because carbon is about one quarter of each CO2 molecule. It's basically--we know for each dollar spent we put out two pounds, a kilogram of carbon, so every time you go and buy something just give them a $1 and say that's two pounds of carbon I'm putting into--of carbon dioxide I'm putting into the atmosphere. It's a not crazy way of thinking about things.

What is worrying people now is that this has been a pretty good decline, but actually this is now turning out to be more significant than people thought. The rate of decline here, that's decline in efficiency of use of carbon, was about 1.3% a year. It's no longer declining and this seems to have continued. It's now going up by 0.3%, 3/10ths of a percent a year, so it looks like the--that we've picked the easy apples, the low hanging fruit as they say, in improving our carbon efficiency and now we may be getting worse again.

Chapter 5. Population and Land Scarcity [00:41:17]

All of that is about how to think--now one of the ways of putting in a quantitative view of the relationship between population and the environmental impact. There are many, many other considerations with the relationship between population and impact. One is the expansion of humans into almost every habitat on earth. There's almost no limit to this so I'll show you some limiting--some extreme cases of this.

What's going on? It's something that Malthus talked about. Remember we described what Malthus said, he's living in England just about 1800 and the population was increasing. What did they do? There was farmland, the best farmland was already farmed, but as there were more farmers, the farmers had to move onto more marginal land, less good land.

What he was thinking was that if there's a law of diminishing returns, that you have farmers on good land, they're producing so much per farmer and it's fairly good. England was not a very poor place. As population increases they have to move onto drier land, swampier land, hillier land, and the production per farmer, for these new farmers, is less than those that had the best land. While the total production grows, and remember Malthus showed a linear rise in total production, that with new people total production grows but population is growing like this.

Since each new person produces less than an old person, he has to farm on worse land than the earlier farmers, the average productivity goes down. That is a thing that has happened all through history. Of course humans when they have a choice of land, when they're not crowded, when nobody else is standing around they choose the best land, the easiest to get along with, to survive in. Then what happens is people move out into less good land.

The pictures I'm going to show you are from Niger which is in Sahel, just south of the Sahara Desert, it actually sticks up into the Sahara Desert, and this is a province of Niger called Azawakh. It's a huge province because there's not many people there, it's a big thing right on the edge of the Sahara. The population is 50,000 people. In the dry season they have two wells in the whole--for that whole huge territory, for that whole--for all those 50,000 people there are only two wells and only one of them works regularly.

During the rainy season and this is what it looks like in that country. They have, you can see, there's no water, nothing growing in the ground, some of the trees that can survive, grass doesn't survive this, it's too small and it loses water, it's gone. Trees can store water basically and survive fairly long periods of drought, so you get some what's called scrub forest.

In the wet season they're very joyous, they have lots of water, they drink lots of water, but this is the amount of water that they have and the people use it for all their functions. The animals, I don't know if you can see an animal back here, the animals use it to drink and relieve themselves and here's girls washing in this water. This is in the good time of the year; this is the water that they have to survive on.

The dry season is nine months long. You have some rain, not a lot, but some rain for three months, then the dry season is nine months long, and then this is the labor value of children. These young girls must travel 35 miles to one of the two wells that are available and that's the average, depending on where they live, that they have to walk--no mechanized transport, they walk 35 miles and they can carry back only enough water so their families can drink one glass a day. Remember we used to be told, it's now shown not to be not really scientific, drink eight glasses of water every day; they're living on one-eighth of that amount of water.

You have to ask yourselves, why do people live in such a God forsaken place? This life is so hard and so miserable, and what is the answer? The better places have somebody on them already. The story, if you can do the sort of anthropological history, is virtually always that this tribe at one point lived in some much nicer place. Some tribe got more populous, got stronger in one way or another was more vicious, and they got pushed out of what was their original, aboriginal fairly decent land onto more marginal land. While they may have been living now for hundreds of years, in a sense, it's not their own choice to live on such a miserable part of the world. When you read I think in the--The War Before Civilization, I gave you some readings in this book which calculated all the violence, it describes some people that had been pushed out into these marginal lands by stronger people, so it gives you a number of examples of that.

Of course the big example, the big modern example is in America, that the European settlers pushed the American Indians, the Native Americans into horrible lands. The stories of pushing the Cherokees from nice farmland and nice productive land in say North Carolina and putting them into Oklahoma which was half dry, or the Apaches and various Indians pushed them off into the desert. You go see how miserably a lot of the American Indians now live in the Navajo reservations and so forth, and say, my God, why do they want to live there? They don't. They didn't want to live there, they weren't given a choice, and they were pushed out.

We're talking about dryness which is one of the things that people just absolutely can't exist without water so this is really the border of existence. But, where it's very wet--you remember you read in Bangladesh that people living on the mud flats and the monsoon season comes in, the water rises or a flood comes, and they're just washed out. Those people didn't choose to live there, there's no land anywhere else, and so they do whatever they can. The Eskimos that live up on the polar ice cap, there are some Eskimos that are constantly--apparently constantly on the ice cap and don't have a base on land.

When we think of people living in these very marginal circumstances, one attributes them then to these famines; people who live in this region have famines every so often. There's great drought, as you know, right now. Parts of Africa have terrible drought. California has a terrible drought, the Colorado River Basin is having drought. So, when this happens, it's always when--the people get into great trouble and they can easily starve to death and some advanced countries may, or may not, send them food, and sending them food has its own problems.

It's always attributed to environmental variability, to climatic troubles. No one ever asks the question, why have these people been pushed into this incredibly inhospitable region? I mean part of the ecology of that region is you're going to have droughts every so often and sometimes they're going to last for years and be very severe. In California, the drought in California has now lasted for years.

Chapter 6. Population and Water Scarcity [00:49:55]

Everything in the environment, the relationship between the population and environments is circular. That people affect the environment and the environment comes and bites them back, it comes back to them. Water is one of the key things and probably what will give out first when we really reach the environmental limit, it will almost certainly be fresh water. There is a lot of information that you can get on this very easily, it's not secret at all. There are two sources of water that humans can use, which is fresh water. You can desalinate salt water but the energy costs are enormous so it's not--unless you're an Arab and sitting on an oil well you really can't do it in any reasonable way.

There's renewable water, which is rain water. When it rains, that is renewable. There's this cycle of it goes up into the atmosphere and comes back down as rain. So you have renewable water coming eventually into rivers and in one way or another you tap the rivers. Then there's mined water, when you mine it just like you mine coal, you dig down and you suck up the water. The greatest productivity of a lot of the farm regions of the world comes from mined water. So--the Midwest of the U.S., especially as you get further west in it, does not have enough rainfall, so they use mined water.

You probably have heard that the reason they can use mined water is that underlying on our Midwest is what's called the Ogallala aquifer. Ogallala is the name of one of the Indian groups that used to live there, the Ogallala aquifer. The farmers all over the west there just sink down a tube and suck up the water. Well you have to think of--being a scientist you always want to know how why, where, all this kind of stuff, and since a kid you read about Artesian wells, and wells to underground water. Then, eventually, you ask yourself, how does water get into rock?

The reason is it drips in there. The Ogallala aquifer actually filled from the melt-off of the last ice age. Apparently the peak of the last ice age was about 18,000 years ago and then it took about 8,000 years to melt until something like 10,000 years ago, those are very approximate numbers. For 8,000 years ice was melting, the ground was soggy, and drip, drip, drip. Rock is never totally solid, there's always somewhere, some little crack and the water slowly drips through the cracks and goes in it. Any kind of--When the rocks get folded, there's caverns in there and any kind of space eventually water will find its way in.

If you ever paid attention to the roof on your house, you know that water gets in, no matter what you do. It's the filling of these aquifers. I don't know--I can't remember when that ice age started, but something that took 8,000 years to fill, but that depended on a glacier which was there for the previous 10,000 years. So, we're talking about a resource that is one of the shorter term resources and it's something like it fills in 20,000 years. Now we're sucking it up in decades and it's very much going way down.

There were some slides, and the reason I was a little late, I could not find the slides this morning, I had them yesterday and I don't know where they went, so I didn't put them on but they showed some interesting kinds of things. That when you're sitting on top of this aquifer you've got the rock and the water, water is incompressible so it holds up the rock. You suck out the water there's now a space there, and what happens, the rock starts crumbling and falling down. What happens is the land actually falls.

In the pictures that I could not find, show first from Houston, Texas a farm there and it's--shows you a pump, it's just a concrete platform with a pump, and you know where the land was and then the land is several feet beneath that. The land is just shrunken, has collapsed. And the second picture I want to show is in Galveston, Texas not so far from Houston, now the land has fallen, again all due to irrigation, but they're near the sea so the salt water has come in and now what used to be good agricultural land is now flooded with the Gulf of Mexico. Are you from that region? She was shaking her head, as maybe she knows.

The most impressive picture comes from the San Joaquin Valley of California. Now, you know probably--That's where all our fruits and vegetables come from, that's a huge source of American food supply. Probably almost all of you today have already today eaten something that was farmed in the San Joaquin. Anybody from that part? Nobody from--we don't have enough farmers at Yale. Well this is a picture of a pole that they put in to measure the drop of the land.

What you see is this very large pole and a man, the man is sort of down here. What the pole is, is the top of the pole is where the land was in--I can't remember like 1957 [1925] or something like that and the land has dropped 30 feet in that time and the man is now 5.5 foot man or a six foot man, is a small fraction of this pole. It's really a shocking kind of photo, and of course the agricultural activity in the valleys of California has only increased since then. The amount of water pumped has increased and the land keeps falling at a very noticeable rate, so it's a very graphic thing.

Now, from when you suck out the water, it takes quite a while for the rock to sort of collapse and fall down because it's got some structural strength to it. If you can see how the much the land has fallen, you can just imagine how much the water table itself has fallen, many times more than the actual land has fallen. In some places you can measure this fairly readily. In parts of Texas and Arizona water tables have dropped hundreds of feet, even in northwest of Chicago there's been a 200 to 300 foot drop in the water table, just sucking it out.

Three quarters of Texas' irrigated area water tables are falling and this is true all over the world. I mean the United States is very technological so we do a lot of drilling, but the north China plain, which is, again, where the wheat in China is grown, drops 40 inches every year. Tamil Nadu in India, southern India, another very productive part of the world, 100 inches a year the water tables are falling.

There's a study that just came out--in February, which measures the groundwater levels that are coming--of the water coming out of the Himalayas. So, the Himalayas, as you know, sit right in the center of Asia and the Yellow River and the Yangtze River sort of feed China, and you have the Helmand River feeds Afghanistan, the Indus River feeds Pakistan and the Ganges River feeds north India and you've got the Ganges goes into Bangladesh, the Brahmaputra, the Meghna all feed the Bangladesh area, then you have the Mekong, and the Salween, and the Irrawaddy, which do Vietnam and Thailand, and Cambodia, and Burma, so all of these come out of the Himalaya mountains.

What's happening? The groundwater in these regions is going down 2 to 4 meters a year so that's 6 to 12, 13 feet every year the water table goes down. Venice is sinking for similar reasons; it's much smaller, only 9 inches in the whole century. Bangkok is sinking 13 centimeters a year.

Mexico City--I hope I have those slides here. Mexico City is sinking in a drastic way there's very--since it's so prominent there's very good data from Mexico City. Mexico City put in a subway, a wonderful subway, if--I had a young lady with me when I was in the subway; aside from getting squeezed you get groped in the Mexico City subway. They laid it flat, but now with the ground--the sucking out of the water the ground is sinking and it doesn't sink evenly, so now the subway is like this and some of it that was underground is now above ground because the ground has just sunken away from the subway.

The sewers and the water supply have exactly the same problem. Water--in Mexico City, the city itself has sunk 30 feet from when the subway was originally put down. Water pipe that was laying flat on the ground in 1934 is now 26 feet over everyone's head and some suburbs are sinking about two feet every year.

Student: How come all this stuff doesn't also just sink down evenly?

Professor Robert Wyman: Because it's all--it's uneven and I don't really know the answer to that. The question is why doesn't everything sort of just sink evenly? It just doesn't happen, so a flat subway ends up like this.

Student: Like the pole in California, why doesn't it just sink to the ground? What is it attached too?

Professor Robert Wyman: I don't know how they arranged that pole, you would think everything would sink, yes I don't know. They may--I don't know, just don't know the answer.

In Mexico City the water supply, as more water is pumped, of course the city--the rate of pumping is faster, the city sinks faster and there's--the pipes eventually get twisted and they rupture so there's now 40,000 repaired--ruptures that they repair each year and many more that they--they're not even reported and they don't get around to repairing them.

Apparently one-third of the water in the system leaks out, and a lot of the city lies below the sewer lines now, so the sewage doesn't leave the city any more, it collects in pools, and they have now had to construct vast pumping stations to pump it out--the sewage back out from these pools. They have--they're building a whole new, much deeper sewage system, they're building 124 miles of 80 foot sewers. That's enough of that. I think you get the message here. Let me have a few more minutes.

Chapter 7. Final Thoughts on Population and Environment [01:01:41]

I put in your reading and just something that you may think, well, why did he put that in, is how much is being paid for caviar and fish and things like that. Its part of a longer piece that I'm not going to have time talk about, but there's a lot of fish in the sea, but there's a lot of people that want to eat fish, so fishing is one of those industries that's really just cleaning out the sea of fish.

When there were small boats, things were okay, the fish could regenerate. But now Korea, and East Germany, and Japan have these huge, huge ships that have miles--their nets are miles and miles long and they just suck everything out of the sea so the fish are disappearing. You'd think that economically that as the fish disappear, and even when they can't reproduce themselves, it would get the--uneconomical to catch the fish anymore.

In actual fact what happens is that, in the fishing, there's presumably good fish that people like to eat, and what happens is, as those get fished out you go down to the next level of fish. If you've been going to restaurants a while you see this, every couple of years there's some new fish on the menu that I've never heard of. Have you had that experience? That's because the fish that you ate two or three years are now gone because they've been fished out, so the quality of the fish goes down and down.

If people have money, they still want to buy the better quality fish and it turns out they will pay almost anything for this better quality fish. What happens is then, instead of the economics working for you, that as it gets more expensive to catch fish, you let off on the fish, the price of the fish goes up, so that it's still worthwhile to catch those fish. What happens then that the--because of that economics, the pressure to catch these fish to extinction keeps up there and some of the outrageous prices that I gave you, that's the point of that kind of stuff.

What you should realize is that environmental destruction is essentially--most of it--a lot of it is irreversible. Loss of species is irreversible, I mean if you want to wait hundred million years, yes species will differentiate and you'll get new species but that's basically irreversible. Things like fishing out various species in the sea so that they don't recover is an irreversible kind of thing.

Loss of habitat is generally irreversible. I think I described to you northeast of Brazil where, or all of Brazil, all of any jungle region where the whole ecosystem is kept going by the amount of fungi that recycle the nutrients in the jungle. When you cut down the trees the sun beats down, kills the fungi, you no longer have this mat of fungi, so now something falls into it, it doesn't get decomposed, the nutrients don't go back into the trees. The whole land dries out and becomes what they call laterite which is hard soil, hard like rock soil, and it's not clear that that ever, ever can recover.

Fish stocks. The cod stocks declined like 20, 30 years ago and they really have not come back, even though they've really cut down the fishing and banned it mostly, they're not coming back. There's apparently too small of a population for the reproduction system to work well. Because this is irreversible, because--this is a very important point, because environmental damage is irreversible as population increases. As the world economy increases, the pressure on the environment gets worse and worse.

You can imagine a nice scenario where eventually population comes down and maybe some of the pressure is let off. But, what you'll have to worry about is that peak because the things that are going to disappear irreversibly, your species, your habitat, your so forth depend not on the level now, but on the maximum demand. That once the maximum--When and if the maximum demand comes off it's ok. What we have to worry about is this peak size of population and other demands on the environment. it's this peak size that becomes important.

We've seen the great range of variability in the UN projections. We could reach a peak at a billion more people, or two billion, or three, or four, or five, or six, or seven, or 12, or who knows how many more billions and which of those curves happens is not going to be a random event. It depends on what humans do right now. Because of momentum, the people that are born now are going to have children and they're a cumulative factor in the environment.

So whatever the birth rate now is, whatever the population growth rate is now, if that eventually stops there's still momentum for another 100 or 150 years. I showed you the data from various countries showing that, even after they reach replacement level fertility, their population grows for another 100 years or so forth. Again, what we do now determines the maximum environmental destruction that's going on.

I think one of the most important points is that environmental solutions are difficult. It is not an easy job to fix the environment. Like global warming, there's huge arguments whether we should try to prevent or should we just try to adapt it, and I think half your courses in the Forestry School are, 'No. It's better to let it happen and it's going to be cheaper to adapt to it." And the other half of the courses are saying "It's a horrible thing, we've got to try to prevent it."

Mostly, like using solar power, wind power--the costs--nuclear power even, the costs are so very high that with current technology the alternatives are really not feasible. What's happening is, China is building a new coal plant every week. They would love to reduce their pollution. They've done whatever they can. But their population is still growing, they have that huge poor population, they need the energy. They have no choice now but to build power plants. What do you tell the Chinese to do? No, you people should keep being poor, don't build the coal power plants. Well we don't say that and they're not going to do it anyway, because their people demand some decent standard of living, which requires energy. So the CO2 in the air goes crazy.

There are no easy fixes for the environment from that kind of side. It's a really very hard job. The only success that one could really claim in the last say 50 years for what you might call the environmental movement is the population, is on the population front. You've seen, I've shown you many, many times that around the third world, up until 1950, 1960, the birthrate was six, seven, eight people--children per woman and now it's dropped to below half that, in fact to about 2.8. So it's something like less than half of that; enormous progress in that area.

I've shown you again in many different ways that people want fewer children in every country, every developing country of the world. You ask, how many they want and--you find out how many they have. In every country the number that they're having is above what they want and massive effects. There's usually--like Bolivia which is not one of your most advanced countries, and universally around the world 70%, 80% of the women want to not have children. 70% just totally don't want it; another 10%--well not in the next two years.

The technology we have, condoms are not wonderful, birth control pills are not wonderful, and they're not wonderful, but they're good enough to do the job. Population is the rare issue where a lot has been done and a lot can be done. We don't have to win the hearts and minds of the people; they're already telling us they want fewer children than they're having.

We don't need new technology. It's dirt cheap compared to the--compared to getting rid of carbon in the atmosphere or reducing it. It's dirt cheap, I mean a cycle of pills on the world market is $0.80, a diaphragm is a $1.25, I mean we're talking dirt cheap. The medical knowledge to provide these things is almost at the barefoot doctor level so you don't need very highly trained personnel, and as I mentioned to you, labor and even educated labor in the developing countries is cheap.

Of all the possible things one can do to improve the environmental situation, it looks to me like encouraging the continued decline of fertility is the easiest thing. You don't have to spend a lot of money, most of the people in the world will be 'Yeah, rah, rah, I want that,' and we've seen from Ryerson's lecture here that with a very little bit--I mean he puts on one soap opera which runs for two, three times a week for like a year which is significant but very small intervention and very cheap, and the number of people going to family planning clinics doubles and triples and it just--an incredible amount of progress with a very small input, so this is a very, very doable thing.

We have a long way to go. The fertility, as I've said, has come down from six, seven, and eight to 2.6 as a global average but 2.6 is still a 30% increase every generation. Population growth, I've just showed you is about a billion people every 13 years now. It's still very high. Bringing it down further is probably the only feasible, reasonably realistic thing that one can do to massive--I mean the environment is going to hell at such a massive rate -- we need some massive change and I don't think anything else comes close to what you can do with population.

I challenge the environmentalists all the time, and I say, look every 13 years there's another billion people. Add up all the environmental--all that conservation, that environmentalists have ever done, all the restoration, add that up and compare that to a footprint of a billion people in 13 years. It's not in the same--you're just not in the same ballpark and yet that message doesn't get through.

There's a wonderful quote, and this is (maybe the--cameras don't even want it), that Peter Beard, who's one of the most famous conservation writers in Africa and he's very outspoken and does not use polite language all the time. This is a quote from him,

"I broke my ass to do these conscientious books." He did all kinds of books on the environment in Africa. "But the public's not getting it at all. You show them photographs of 30,000 carcasses with the ivory tusks still in place," that's elephants--30,000 ivory elephants, "And the tusks are still in place and they try to tell you that we should prosecute poachers" as if that was the issue. "Doesn't anyone realize that people are hungry and using these animals for food? People still think its wild Africa. Doesn't anyone realize that this is all about population pressure? What the"--and he uses the 'F' word, "What the 'F's' going on out there in the CONservation word?" He capitalizes "con" as for con job, "Nothing but lies, fundraising lies."

I think we are--I mean he overstates things, and as you know, that's one of my pedagogical tools is to engage somewhat in overstatement. You remember it though. The whole environmental movement has got its head in the sand about the one thing that could really probably make a big difference.

Just to conclude, the earth is in a big race. I've shown you population is increasing, environmental problems are increasing, but fertility is coming down. Depending on how these two countervailing forces work, in the future we will either come to a smooth landing, a soft landing, that fertility will come down fast enough that takes the pressure off the increasing environmental issues, or it won't, or population won't come down fast enough. Then we're off into who knows what.

That's I think what to take away from this course, the tremendous race between the increase of population, a billion people every 13 years, the decline in fertility, a decline since 1960 in about 40, 50 years declined to more than half. How is that race going to be won and what are we--which side is going to win that race and what can we politically--what can we do about it?

Have a good summer and have a good test.

[Applause]

[end of transcript]