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Between now and 2050, three billion people will join the six billion-plus that already live on this planet. How will we possibly feed them? Lester Brown, population expert, founder of the environmental think tanks Worldwatch Institute and Earth Policy Institute, and a man whom the Washington Post has called "one of the world's most influential thinkers," has been consumed by this question for decades. In this sobering interview, Brown addresses this conundrum and its complicating factors, such as the falling water tables and rising global temperatures that imminently threaten our world's food supply.

Three billion more

NOVA: Some people say, "Oh, those dire predictions of Paul Ehrlich, they were all wrong." Is the population explosion over?

Brown: If we define the population explosion in terms of the rate of growth, the historical rate of growth peaked somewhere around 1970 at about 2 percent. It's now down to 1.2 percent or so. But 1.2 percent of the population the size of the world population today, 6.3 billion, still gives us some 74 million more people each year. That's less than the 85 million we were adding annually a decade or so ago, but it is still more people to feed each year.

Adding 74 million each year is equivalent to adding 2.5 Canadas each year. It's not a trivial addition to world population, particularly at a time when cropland is becoming so scarce and water shortages are now cropping up. Not only is almost all the projected population growth going to be in the developing world, but the vast majority of the nearly three billion people to be added by 2050 will come in countries where water tables are already falling and wells are going dry. That's not a recipe for economic progress and political stability.

NOVA: Can the Earth support three billion more people?

Brown: The question is, if we look at it just in food terms, at what level of living? If we're talking about living at food-consumption levels today of, say, the average person in India, then the current world harvest can support 10 billion people. But if we're talking about the U.S. level of consumption, then we're talking about a world that will support two and a half billion people.

And the question is, at what level do people want to live? We look at the poor countries and realize they're not really consuming all that much, but the bottom line is they all want to consume as we do. And what we're seeing in China today is that desire to consume being realized on a scale we've not seen before.

NOVA: Projections for world population growth have been revised downward in recent years. Why is this?

Brown: The combination of advances in living standards and broader access to family planning services are accelerating the shift to smaller families. But now just within the last few years, we've begun to see projections of population being lowered not because of falling birthrates, but because of rising death rates.

In Africa, for example, life expectancy in a number of countries was expected to reach 65 years without AIDS. With AIDS, it's now been dropped, in some of these countries, to something like 47 years, an unprecedented drop in life expectancy affecting hundreds of millions of people. This is the first time in modern history that we've actually seen such a precipitous drop in life expectancy.

“There are now 6,000 Africans dying each day from AIDS. That’s 15 fully loaded jumbo jets crashing each day with no survivors.”

The thing that's so disturbing is that we knew that HIV infection rates were rising in Africa. We knew that by the late '80s, but it's only been within the last two or three years that the international community and national governments in many of these countries have recognized the threat.

Developing trends

NOVA: The United Nations thinks that India's population will stabilize in this century, meaning that on average it will have two-child families or less. Do you think that's realistic?

Brown: When we look at India's projected population, another half billion by 2050, I have some real doubts as to whether that half billion will materialize. The question is whether it will not materialize because we get our act together and accelerate the shift to smaller families, or because we fail to do so and water shortages translating into food shortages raise the level of malnutrition and hunger. If India does not act quickly to stabilize water tables and to accelerate the shift to smaller families, we could see rising death rates because of hunger, in the same way we've seen rising death rates in recent years in Africa because of the failure to control the HIV epidemic.

NOVA: What about sub-Saharan Africa? It's in the midst of a genuine population explosion, right?

Brown: Africa's in an interesting situation, because it has the highest fertility of any region in the world, but it has also seen an extraordinary rise in death rates. There are now 6,000 Africans dying each day from AIDS. That's 15 fully loaded jumbo jets crashing each day with no survivors. Africa loses more than twice as many people from AIDS each day as we lost in the U.S. when the Twin Towers went down on September 11th.

We have not yet adequately incorporated the effects of those rising death rates in projections of future population growth in Africa. There are some African countries now in which there are actually projected declines in population once the heavy toll in human life of the HIV epidemic is taken into account. It does not now seem likely that the population growth that was once projected for Africa will materialize. But it will not materialize for the wrong reason: it is because of rising death rates, when what we desperately have wanted is for it to occur because of falling birthrates.

NOVA: What happens if countries can't stabilize their populations? Will they just eventually break down?

Brown: One of the things that's happening in the world today as our numbers have passed the six billion mark is that in order to support six billion-plus people, we are over-consuming the Earth's natural capital. Forests are shrinking, fisheries are collapsing, water tables are falling, soils are eroding, grasslands are deteriorating from over-grazing. This over-consumption of natural capital artificially inflates economic output, including food output. We are developing a bubble economy.

The worrisome thing about bubble economies is that if you can't shrink the bubble, eventually it will burst. Then you have serious problems. We've seen bubble economies develop in the high-tech stock market in the U.S. We saw the value of high-tech stocks drop by 60 percent or so. We saw this with real estate in Japan a decade ago, when suddenly the bubble burst overnight and real estate prices also dropped by 60 percent.

Grain drain

NOVA: What about the impact of growing populations on the environment?

Brown: Well, those of us who have been working on environmental issues for many, many years now have been saying for some time that if we do not reverse the environmental trends of recent decades, eventually we will be in trouble. What has not been clear is what form that trouble would take, and when it would come.

“Can the world’s farmers dig our way out of this 100 million-ton hole in 2004 and feed 70 million more people?”

My sense now is that the trouble is going to come on the food front. Half the world's people now live in countries where water tables are falling. This includes the big three grain producers—China, India, and the United States—which account for nearly one half of the world grain harvest.

Recent research at the International Rice Research Institute looking at the precise relationship between temperature and crop yields indicates that each 1°C rise in temperature above the optimum during the growing season leads to a 10 percent decline in grain yields—wheat, rice, and corn. Those results have been confirmed by crop ecologists at the U.S. Department of Agriculture.

Falling water tables and rising temperatures are two of the key reasons why the world grain harvest has not increased at all over the last eight years. And in the last four years we've run up record deficits: 93 million tons last year, 105 million tons this year. These four consecutive years of grain deficits have reduced world grain stocks to the lowest level in 30 years. The big question now is: can the world's farmers dig our way out of this 100 million-ton hole in 2004 and feed 70 million more people? They may not be able to.

NOVA: You've talked about the Green Revolution coming to a close. Why is that?

Brown: In 1965, I was invited to India as an employee of the U.S. Department of Agriculture to help review a draft of the agricultural part of the new five-year plan. I helped fashion the new program, and we did a number of things, including setting the stage for introducing large quantities of the new high-yielding wheats that were already so successful on demonstration plots in India. The result of these improvements was that India doubled its wheat harvest in seven years. No major country had ever so rapidly doubled a major food staple as India did with wheat. And since then India has more than doubled its total grain production.

But if I were invited to India today to again draft a new plan for India to dramatically expand its food production, as will be needed to feed the half billion people to be added to the current population of over a billion, I would be hard-pressed to come up with more than some relatively modest increases here and there. That's true, I think, not only for me but for almost anyone working in agriculture. We can get 2 percent here, 5 percent there, and maybe 10 percent some other place. But the doublings of grain harvests in major producing countries now appears to be history.

NOVA: Why?

Brown: The reason is we've pushed up against a biological limit. I sometimes liken it to our running speeds for the mile. By the time of the first modern Olympics in 1896 we were under five minutes. Then in 1954, Roger Bannister, an English medical student, broke four minutes. But no one ever talks about a three-minute mile, because physiologically it just doesn't appear to be a realistic prospect. Similarly with grain yields: you can double or even triple them, but then it becomes much more difficult because of physiological constraints.

NOVA: What about China? What critical problems will it face in the coming decades, and how will they affect the rest of the world?

Brown: We probably don't need to go beyond the food issue to see how what's happening in China is going to affect the rest of the world. Between 1950 and 1998, China's grain production went from 90 million tons to 392 million tons. It was one of the world's major economic achievements in the last half century. But then, after 1998, grain production started to drop. One of the reasons was because of spreading water shortages. Between 1998 and 2003, grain production fell from 392 million tons to 322 million tons. This drop of 70 million tons is greater than the grain harvest of Canada. It also exceeds the grain exports of Canada, Australia, and Argentina combined.

“Like it or not, we’re going to be sharing our food with 1.3 billion increasingly affluent Chinese consumers.”

China has been covering this downturn in its grain production by drawing down its once massive stocks of grain. But it's now reached the point where they are largely depleted, and so within the next year or two, China will be turning to the world market for massive imports of grain—40, 50, 60 million tons, more than any country in history has ever imported. And when China turns to the world grain market, it will necessarily turn to the U.S., because we control almost half of the world's grain exports.

What we're looking at is a fascinating geopolitical situation, in which we have 1.3 billion Chinese consumers who have a $100 billion trade surplus with the United States competing with us for our grain, driving up food prices, not only for us but for the entire world. Suddenly the Chinese will realize that they are heavily dependent upon the outside world for part of their food supply for the first time in their history. And we will realize that, like it or not, we're going to be sharing our food with 1.3 billion increasingly affluent Chinese consumers.

Big picture

NOVA: What will the rising affluence of such a huge number of people mean for the world?

Brown: China was once a billion poor people. But it's no longer a poor country. China produces and uses more steel than the United States. Chinese farmers use more fertilizers than U.S. farmers in total. China consumes far more grain than the U.S. does, not in per-capita terms but in total because of the sheer size of its population and because the Chinese are consuming much more per person now. So in terms of the overall economy, we're looking at some enormous growth and demands on resources.

This growth brings up the question of whether the Western industrial development model—that is, the fossil-fuel-based, automobile-centered, throwaway economy—is going to work for China. Clearly it will not. And if it doesn't work for China, it's not going to work for India or for the other two billion people in the developing world.

So while we're looking at population growth—another three billion according to the U.N. medium projections—we have to think about what that translates into if living levels keep rising in most of the world. The bottom line is we're going to have to restructure the global economy if we want to sustain economic progress, because the existing model simply will not satisfy the needs of these growing numbers without destroying its support systems, which is already happening.

NOVA: When you look at all these trends, do we still have time? Is it within our power to tip the balance to shape the kind of future we want?

Brown: Within the next few years, rising food prices may be the first global economic indicator to signal serious trouble in the relationship between us now, 6.3 billion, and the Earth's natural systems and resources on which we depend. Then the question is: how will we respond to this wake-up call? We may respond very positively. I mean, it's interesting to look back historically, and when countries or civilizations are in trouble, they may have a Nero or they may have a Churchill. You never know. In a global crisis, of course, there are a lot of leaders that play key roles.

“What we decide will quite literally shape the future course of history.”

But with the water crunch translating into a food crunch in the next few years, I think we're going to have to make some difficult choices, including on the climate front. These are not choices that can be put off for future generations to handle. We will have to deal with the issues of population growth, falling water tables, and rising temperatures one way or the other. What we decide will quite literally shape the future course of history.

NOVA: When you look at the world, what do you think are the prospects for its future?

Brown: In looking at the future, and the projected growth in population of nearly three billion more people by mid-century, at a time when water tables are falling, and temperatures are rising, making it more difficult to expand food production, then rising food prices may be the wake-up call that will force us to rethink things in a very fundamental way. And then the question is: how quickly can we change? And social change is not always that predictable.

For example, when the Berlin Wall came down in 1989, and we had a political revolution in Eastern Europe, an essentially bloodless political revolution, this was not widely anticipated. You could search the political science journals of the 1980s, and you wouldn't find a single political scientist who said, "Keep your eye on Eastern Europe, there are big changes coming there." But one day people woke up and realized that the great socialist experiment was over, that the one-party political system, the centrally planned economy, was not working.

The Berlin Wall was kind of the symbol of that change. But people woke up one morning, and even the people in power realized that the system wasn't working anymore and that change was inevitable. Something like that may come on the food front. Consider what happens if it becomes clear that rising temperatures that whither harvests—as they did in India and the U.S. in 2002 and in Europe in 2003—are shrinking harvests and raising food prices. Suddenly we'll have a massive new lobby, consumers who will want to reduce carbon emissions. Then we may see governments begin to take global warming seriously in a way that we have not up until now.

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