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GLOBAL-CHANGE CAUSES AND REMEDIES

Up to this point, we've looked in depth at two of the most prominent issues of global change, stratospheric ozone depletion and an increased greenhouse effect. Before we take up other environmental problems, such as acid rain and air pollution, this is a good opportunity to step back and look at global environmental concerns in sum. Why are these concerns coming to the fore at this particular time in history? What can we as a species hope to do about the most pressing aspects of global change? These are the vital issues we shall examine next.

Let's discuss these global problems in terms of the number of people on the planet. If you're still wondering why the major global-change problems all seem to be arising now, a few facts will bring the fundamental reason home in a hurry.

What is remarkable about our time is the rate at which the world's population is growing. In the four seconds it takes you to read this sentence, there are 16 more people on Earth. In two days' time, the population of the planet will increase by enough people to populate another San Francisco. It took almost the entire history of the human race for global population to grow to 2 billion, a magnitude that was not achieved until the early 1930s. Since then, the rate of growth has been astounding, by any measure. The 3 billion mark was passed in 1960. Population exceeded 4 billion in 1974. The 5 billion figure was reached in 1987.

Global population in 1993 was about 5.6 billion, and the annual increase in recent years has been almost 90 million. The annual increase

is the difference between the number of people who are born and the number who die each year. So each year, nearly 90 million more people are born than die. Thus, 90 million is the net increase, not the number of births. Incidentally, if you add together the current populations of Great Britain, Ireland, Iceland, Belgium, Denmark, Norway, Sweden, and Finland—nearly all of northern Europe outside of Germany—the total is not far from 90 million. Another way to dramatize the rate at which population is increasing is to realize that the demographic equivalent of another Switzerland is being added to Earth every month.

Even if this rate of increase—this nearly 90 million per year—were to remain constant, every decade or so we would continue to add almost another billion people to the Earth. Furthermore, most of the increase today is occurring in developing countries, such as India. During 1993, India's population increased by nearly 17 million. That was more than the combined increase of Europe, the former Soviet Union, all of Latin America, and the United States. In 1993, 94% of the world's population growth occurred in developing countries. Of the 5.6 billion people on Earth, more than three out of every four people now live in developing nations.

So there you see exponential growth in very dramatic terms. It's thus no accident that the enhanced greenhouse effect, acid rain, and the ozone hole, all of which are examples of planetary consequences of human activity, are occurring now. There just are more of us now. We're also living in ways different from our forebears; in particular, we use vastly more energy. All of these facets of global change are, in one way or another, by-products of the way we live and use energy.

How many people will there be in the year 2100? Demographers estimate that, barring catastrophe, there will be at least 9 billion human beings on Earth, no matter what is done in an effort to reduce population growth. Without any real attempt at serious measures to limit population, that number might be even more. The United Nations estimated in 1982 that world population would stabilize in 2100 at a level of 10.2 billion people. Today, that estimate appears to have been overly optimistic. The U.N. now expects population growth to continue beyond the year 2200, and that the total global population will reach 11.6 billion, more than twice the number of people alive today.

Africa is the fastest-growing region, and, because today 45% of Africans are not yet 15 years old, their childbearing years are still ahead of them, and there is little likelihood that African population-growth rates

will soon decline sharply. In China, by contrast, population growth has slowed dramatically. There, the total fertility rate, the number of children borne by the average woman during her lifetime, dropped dramatically from 2.3 to 1.9 between 1991 and 1993. Much of this drop can probably be attributed to an increasingly harsh enforcement of the Chinese government policy decreeing strictly that each couple should have only one child.

If we were to assume that absolutely nothing affecting population would change, and that we would continue to experience these rates of population growth, how long could the Earth survive? The answer is that the Earth will be around, at best estimates, for several billion years. The more interesting question is: How much time do we have? "Saving the planet" is a sloppy use of language. What we're talking about is saving us.

My answer, and it is not from any special source of wisdom, is that the amount of time you have depends very much on who you are and where you live. The rich people in the developed countries have a relatively long time before they must face the consequences of a world with too many people on it, but the poorest people in the Third World are already in a disastrous situation. The Malthusian catastrophe of death by starvation and disease is already a reality. It's not happening in the fashionable neighborhoods of the great cities of Europe, Japan, or North America. It's happening in countries such as Chad, Somalia, and Ethiopia.

All of this is germane to the issues we've talked about. If the climate change that accompanies an increase in the greenhouse effect results in changing patterns of rainfall and drought, for example, the agriculture that may be best able to adapt is the well-developed agriculture of the First World, with irrigation, advanced soil science, genetically engineered crops, and the like. In regions where there's already too little food to teed too many people, and where there's no adequate infrastructure, the people and their governments simply do not have these options. There is no way for them to respond to the threats posed by climate change. Those are the areas that will be in the worst trouble.

Thus, the answer to the question, "How much time do we have?" is not a single number of years, but rather depends on several factors, just as the answer to the question, "What will the climate change be?" is not a single number, like 2, 4, or 6 degrees of warming. The answer to the

climate question involves a whole complex of issues having to do with all aspects of climate, including frequency of droughts, rising sea level, extremes of temperature, and changes in El Niños and Indian monsoons. We use temperature in this context as a metaphor; I've compared it to fever, a symptom but not a description, of a human disease.

Expressing the number of years that we have left before an overpopulation catastrophe befalls us is a useful metaphor, and a way of making these issues concrete. But the real truth is that the repercussions of excessive population are likely to be highly uneven. And that is as it has arrays been. Throughout history, ordinary people have always been more vulnerable to natural calamities than the wealthy and privileged.

Some of us like to look at this situation optimistically. We like to think ours is a savvy species, that we can fix anything. If we caused a problem, then we'll find a solution for it. If you want to think optimistically in those terms—as I do—consider this: Perhaps the very fact that the planet is so teeming with people now, and the fact that the consequences of this heavy population burden are becoming clear in so many ways, will spur us to attack the fundamental problem of how to limit the number of people on the planet. How do we, to use the catch phrase of today, design a sustainable planet? How do we reach an equilibrium?

With that in mind, let's look at how a couple of countries compare in terms of what they do to the global environment. Let's use the problem of carbon dioxide adding to the greenhouse effect as our illustrative example. If we get our energy mainly from fossil fuels, and if that energy production is the source of the CO₂ we add to the atmosphere, then one way to estimate how much a given country increases the greenhouse effect is to calculate how much energy it uses. With these assumptions, the calculation is easy to do. We'll use approximate data from about 1990. The first country we'll consider is the United States.

There were about 250 million people in the United States in 1990, and they used about 280 gigajoules of commercial energy (energy that comes from a power plant as opposed to a wood stove) per person per year (giga means billion and a joule is a metric unit). An idle person, or a conscientious person trying to conserve energy, might use considerably less, whereas someone who flies often can easily be responsible for three or four times as much energy usage as the average American. But on average, the figure is around 280 gigajoules per person. Then the

total energy usage (gigajoules per year per person, multiplied by number of people) is 280 times 250 million people, or 70 billion gigajoules per year.

Let's take another country. For India in 1990, population was about 835 million, more than three times the U.S. population. But per-capita commercial energy consumption for India was only around 8 gigajoules, compared to the U.S. value of 280. The product for India is, therefore, about 7 billion gigajoules per year, in round numbers, compared to 70 for the United States Thus, India, with more than three times the U.S. population, has only about one-tenth the U.S. effect on the environment, using the assumptions made above.

That remarkable result is at least qualitatively consistent with a number of other striking facts. For example, about 75% of the carbon dioxide put into the atmosphere now comes from rich First World countries, such as the United States, Canada, Japan, Australia, and the nations of Western Europe. By contrast, more than 75% of the world's people now live in developing countries, where per-capita energy usage is generally much lower than that in the First World. So 25% of the people are producing 75% of the problem. CO₂ is released whenever we make energy by burning fuels like coal, oil, and natural gas. To date, Indians are not for the most part driving many cars or heating and air conditioning large houses or using large amounts of electricity. Bearing in mind that nearly all the world's population growth is occurring in the Third World, the calculation of a country's CO₂ production that we just undertook should warn us about the likely future course of the enhanced greenhouse effect. It illustrates dramatically that the largest potential danger of massive additional CO₂ emissions is to be found not in the First World, but in the developing countries.

A calculation this simple can't be stretched too far. But we can test it to sec whether its consequences make sense. Certainly, if it is CO₂ that we're interested in, and if the CO₂ comes from burning fossil fuels, then our calculation is probably a pretty good first estimate, because it just says that the amount of CO₂ released is going to be proportional to the amount of energy used. It assumes that we're producing energy by burning coal, oil, and gas to make the CO₂ .

This sort of calculation does ignore the differences in CO₂ emissions among the various fossil fuels. For example, extracting a given amount of energy from coal produces more CO₂ than would be the case if you used oil, which in turn produces more than would be produced by natural gas. In fact, coal is about twice as "dirty" as natural gas, in terms

of how much CO₂ is released to obtain a given amount of energy. These differences, which stem from differences in the carbon content per unit of energy from the various fuels, are not considered in this simplified calculation, but could be incorporated (and are, by scientists) if we wanted a more accurate result.

In doing this calculation, we're assuming additionally that the adverse effect of energy production on the environment lies simply in the amount of CO₂ emitted. That is indeed going to be the product of the population times the amount of CO₂ for which each person is responsible, which we have further assumed is proportional to the energy we use. For CO₂ , the culprit we've been using as a paradigm global-change example, this is probably a fairly reasonable means of constructing a first idea of the magnitude of our contribution to increasing the greenhouse effect. Our technique, however, ignores all the other adverse environmental consequences of using fossil fuels as an energy source.

One of the advantages of a simple theoretical model, like this calculation, is that it helps to make clearer some of the things we've discussed before, and it allows us to evaluate the consequences of actions we might take. For example, the United States could make a serious effort to cut back its fossil fuel use, but even if it did so, this effort alone would not necessarily reduce the global problem in a major way. Why? Because just a slight increase in the per-capita energy consumption of developing countries with large populations could more than offset the U.S. action. As time goes on, Americans will contribute a smaller percentage of the world total of CO₂ emissions, and unilateral action to reduce U.S. emissions will have a proportionately lesser effect. Nevertheless, the United States and the other wealthy industrial countries must clearly play a leadership role if the developing nations are to avoid the inefficient and environmentally hazardous fossil-fuel route that the developed countries have generally taken.

Consider the probable future growth of population in India. If you make optimistic estimates about the success of birth control, which is a monumental problem in India—and for this purpose you can encourage birth control any way you want, through abstinence, contraceptives, or other methods—the optimistic estimates predict that India's population will reach at least 2 billion, over roughly the next century. Barring some unforeseen catastrophe, such as war or epidemic, this estimate implies that the population of India will inevitably grow by a factor of nearly two and a half, from, say, 835 million to 2 billion. It's frightening to realize that the population of the entire world in the early 1930s was

2 billion, and that the same number of human beings are now apparently destined to be crammed onto the Indian subcontinent.

Incidentally, it's now widely recognized that the key to reducing birth rates and lowering family sizes is not simply distributing condoms and birth-control pills, but also taking a range of other actions, always including educating and empowering women. Family planning must be combined with the provision of improved health care. Governments need to adopt and actively support policies that emphasize the desirability of small families, and a variety of contraceptive techniques must be made readily available. Infant mortality rates must be reduced, so that families won't produce many children in hopes that some will survive. In countries where total fertility rates are now highest, these conditions have emphatically not been achieved. It's still true today in some African nations that an average woman will bear seven or more children during her lifetime.

The great majority of the nearly 90 million people currently added each year to the planet live in the Third World, including China and India, the two countries with the largest populations. China's population is only slightly larger than India's, a little more than a billion right now. But in India there appear to be cultural barriers to population control that do not exist in China. And because there is no authoritarian central government in India, India's population may well overtake China's on the way to reaching the 2-billion mark. We're speaking about only a few decades; it need not take very long for India to become the most populous nation on Earth.

Thus, even with a relatively small increase in India's per-capita energy consumption—you needn't equip each Indian family with a large American-style house and air conditioning and three inefficient cars, but just allow it a modest increase in energy usage—the population multiplier is so great that it could easily swamp any effort to cut back fossil-fuel use in the United States, and global emissions of CO₂ could continue to increase.

What should we do about this? Once you have these kinds of numbers staring you in the face, what is the best response?

The appropriate response to the problem of climate change caused by an enhanced greenhouse effect must be global. This problem is unlike those that are solvable by relatively local means, like urban air pollution. It's also unlike global problems that have technological fixes, like ozone

depletion, which can be stemmed by eliminating chlorofluorocarbons and related compounds.

The first principle likely to earn widespread support is that we ought not to use the lack of scientific certainty as an excuse for postponing all actions. When we analyzed the various climate-model predictions and saw how broadly they differed, we could agree that the large differences among them mean that at most one of these models is right, and more likely that none is exactly right. You could ask, given that level of scientific uncertainty, can we not postpone action altogether? The plain fact is that population and fossil-fuel use are increasing in the meantime, and we would be knowingly exacerbating the problem while waiting for the scientists to understand it better.

An analogy used by Paul Ehrlich of Stanford University is this: Suppose there is only a 5% chance that the environmental change is going to be gravely serious. Suppose, that is, that the science is so uncertain that there's only one chance in 20 that we will have, for example, a catastrophic rise in sea level or a catastrophic disruption of agricultural productivity. Would you get on an airplane if the chances were one in 20 that it would crash? Probably not. An eventuality that yields such serious consequences is well worth worrying about, low likelihood or not.

A second principle with wide appeal is to take actions that have other benefits, so-called collateral benefits. By this I mean the sorts of things that people agree are "win-win" propositions, the ones that would benefit humankind even if climate change were not a concern. For example, improved energy efficiency, additional energy conservation, and increased use of renewable sources of energy are at the top of almost everybody's list. Those measures would decrease environmental damage in other ways, even if there were no serious climatic change to worry about, even if the climate turns out to be robust and resilient in ways that we have not foreseen. The process of extracting energy from fossil fuels has many other adverse environmental consequences, like smog, like tanker accidents, and like what happens to a piece of the Earth where a strip mine operates. So reducing the use of fossil fuels reduces pollution in general. It also reduces acid precipitation and deposition (acid rain and its solid equivalent), which is mainly a product of the burning of high-sulfur coal.

Depending on how you go about reducing the use of fossil fuels, you have a chance to yield some other benefits as well. For example, the

retail price of gasoline in Europe is much higher than in the United States, because gasoline is heavily taxed in Europe. The United States could consider the European stance carefully but then conclude that a $3-a-gallon gasoline tax imposed tomorrow morning in the United States would be unacceptably punitive, especially on people least able to pay it. It would be a regressive tax—the impact of sales taxes generally falls hardest on the poorest people.

But let's say the United States gradually phased in some sort of "carbon tax," and not necessarily a $3-a-gallon gasoline tax, over some considerable time, so that people got used to it. After all, Americans didn't get used to income tax immediately; it was phased in gradually over time, and now Americans think it's normal. If the United States introduced a carbon tax like that, and if it were one that people agreed was an equitable way to achieve a socially worthwhile goal, then the tax would not only motivate people to use less gasoline—by buying more fuel-efficient cars, living closer to work, walking or biking to work, car pooling, telecommuting, etc.—but it would also generate revenue. The United States could then use that revenue, for example, as is done in some other countries, to help promote mass transit, which would help relieve the burden on the people on whom the gasoline tax hits hardest. These same people might be the ones to gain the most benefit from buses, light rail, van pools, and other conveyances that could be bought with the money from the carbon tax. That's one scenario.

At the same time, Americans might find other economic benefits as well. Since a significant fraction of the fossil fuel used in the United States is imported oil, the country would decrease its trade deficit, reduce its balance-of-payments problem, and increase national security through lower dependence on foreign sources of energy. And those who would be spending less money on gasoline would have more money to spend on something else. A carbon tax might even promote activities that are healthful and socially worthwhile, too, like walking.

The rich countries generally do not have rapidly increasing populations. Some rich countries, notably Japan and certain Western European countries, have already effectively achieved zero population growth. And other countries are rather close to it. The United States, unfortunately, is an exception. In round numbers, the U.S. population is growing by about 3 million people per year. Of this number, approximately 2 million results from the excess of births over deaths, and about 1

million from immigration. In the early 1990s, the total fertility rate, the average number of children born by each woman in the United States, rose above 2.0 for the first time in 20 years. It's now about 2.1. That's regression, not progress toward a sustainable future.

For the wealthy countries, sustainable development—development that can be kept up for some considerable time—may not mean an increase in gross national product. It might mean a decrease in gross national product and an increase in quality of life.

To pick an example, if you think people are better off when they ride bicycles than when they drive cars, then every time you alter the transportation system away from motor vehicles and toward bicycles, you have increased the quality of life while decreasing energy consumption and carbon-dioxide production. That's an option that's open to rich countries.

The converse is the scary part. Even if you believe global population can soon be stabilized—and nobody thinks it can be at 6 billion, though some are sanguine about less than 10 billion—you're dangerously mistaken to think that you can enjoy perpetual economic growth based on fossil fuels as the primary energy source. If you think you can keep population constant in a country or in the world and just keep increasing the amount of fossil fuel that each person consumes, then you're being naive about the capacity of the Earth as a life-support system to handle the environmental consequences. Indefinitely continuing economic growth will require weaning humankind from its dependence on coal, oil, and natural gas.

If you agree with all that, then you'll agree that the global challenge is social and political as much as it is technological. It requires cooperation. The world has first to agree on what to do about this kind of problem, and then act on it.

When you consider the implications for our daily lives, the actions that we take individually are clearly helpful. It's helpful to use less water, bike to work, and conserve energy, and it's especially important for people in wealthy, industrialized nations to take such actions, because their per-capita energy usage is so much higher than in the developing world. People in the United States have the luxury of choosing to change their lifestyles, because few of them worry every day simply about feeding themselves. An additional benefit of taking individual action is that such action becomes an educational tool and a reminder,

just as, for a religious person, a symbol like a rosary or yarmulke does not itself guarantee a good, moral, upright, religious life but, rather, reminds the person of the value of living such a life.

Recycling, for example, has the virtue of keeping people conscious of the importance of reducing the consumption of resources. But bringing resource consumption under control on a worldwide basis also requires that world opinion have an effect on the countries with the largest populations or rates of population growth, like India and China and several other countries in Asia and Africa.

Reforestation is also on everybody's list of good things to do. Forests are wonderful things: they provide habitats for many species; and the biological diversity of the Earth is largely concentrated in the tropical forests. The numbers are very uncertain, but biologists have classified about 1.4 million species of living things. But estimates for how many species have yet to be discovered range from about 10 million up to about 30 million. So even by the most conservative estimates, there are many more species yet to be discovered and studied and classified.

Why should we worry about that? Because of both practical benefits and long-term concerns. The species of plants and animals on Earth represent a kind of genetic treasure chest. They are the bank on which evolution draws for evolving further species, and once one of them is gone it cannot be replaced. Several species become extinct every day. The loss from deforestation alone has been estimated at 4,000 to 6,000 species per year. Although less than 10% of the land area of the world is in the tropics, the great bulk of the variety of land species is there. The tropical rainforest is an especially valuable part of the world. The rainforest, which is being lost at an alarming rate, perhaps as much as 10% per decade, supports a large fraction of the plant and animal species that will be gone before we learn anything about them.

Even if you take the especially self-aggrandizing and arrogant attitude that the purpose of the Earth is simply to serve human beings, there are many good, selfish reasons for wanting to preserve biological diversity. Pharmaceuticals derived from plants and animals are an example. Foods are another.

There are other benefits from reforesting. If we reforest on a sufficiently grand scale, we help stem the increase in atmospheric carbon dioxide, with all its possible climate consequences. We also reduce air pollution. Trees do make certain hydrocarbons, but they also take in chemicals that would otherwise be pollutants. Additionally, trees are powerful controllers of the local climate. The forest is also a source of

timber, recreation, and so on. In short, reforesting, which has to be done on a very large scale to make any significant difference to atmospheric CO₂ concentrations, has side benefits that are worth pursuing, even if fixing the climate problem is not one of them.

Perhaps, then, we should carefully consider reforesting. But like recycling, reforesting is not a panacea for global-change issues. It cannot solve the problem of climate change caused by humans adding CO₂ and other greenhouse gases to the atmosphere. That problem is caused by how people live and how they produce and use energy. Solving that problem means adopting measures that promote energy efficiency, energy conservation, and a switch to renewable sources of energy, not to mention promoting reduced population. These are actions that must be taken globally and soon.

Consider the parable of the boiled frog. An alert frog dropped in a pot of boiling water will jump out. It will be shocked and traumatized, but it will survive. But if placed in lukewarm water and gradually heated, the wretched animal will adjust to the changing temperature without realizing it and end its days as frog soup. I don't know whether this is true or not; this is a parable, not an experiment that anyone has performed or should perform. The point is, the impact on the frog of a gradual warming is insidious.

Energy consumption from fossil fuels is growing slowly and insidiously too in many parts of the world. When we consider the consequences of China's industrializing on the Western model, using the centuries of coal supply that it possesses—which is both feasible technologically and tempting economically because China already owns the coal—we're recognizing that the world may be like the frog in the pan of lukewarm water that is gradually heating up. Then we'll be watching global population continue to increase and fossil-fuel use continue to increase, and the product of these two factors will increase more rapidly than either of them alone. If that pattern persists long enough, it is virtually inevitable that the carbon-dioxide increase will eventually have a substantial effect on climate.

The ultimate pessimistic viewpoint is that we as a species are incapable of change. A good many people, apparently sharing this viewpoint, claim that it's just impractical, unrealistic, and politically naive to expect people to make big changes in the way they live. They point to the U.S. auto industry, for example, as an industry on which many other industries and people are dependent, and one that historically has been based

on the production of large, fuel-inefficient cars. And they point out the dominant nature of this industry: manufacturing automobiles is the largest industry in the world, and supplying the fuel for them is the second largest. Six of the top ten industrial companies in the United States arc either oil companies or car companies, and these giants do not easily accept change.

One counterargument is that the auto industry has already dramatically changed. For example, the average new car in the United States now gets around 30 miles to the gallon, which is about double the fuel efficiency that was typical 20 or 30 years ago. And cars now feature numerous technological advances such as air bags, which we were told for years no one would buy, couldn't be produced affordably, and couldn't be made reliable. The state of the car today, with carburetors and distributors replaced by electronic fuel injectors and microcomputers, is unrecognizably different from that of only a few years ago. And recent technological developments arc setting the stage for even more rapid and innovative advances. Cars planned for the not-so-distant future may perhaps best be thought of as computers on wheels. The most imaginative of them will not be made of steel or fueled by oil products. They arc likely to be small, light, sate, and incredibly fuel-efficient compared even to today's cars. The counterargument, in short, is that change is inevitable, and the need for beneficial change spurs technological development.

Of course, energy conservation and energy efficiency are at the top of everybody's list as ways to cope with these problems. Perhaps the realization that the problems are real and that the time to act is now, not a generation or two from now, will spur progress in those areas.

At the same time, perhaps the situation will encourage us to hunt for the kind of political and technological solutions that we're finding for chlorofluorocarbons, but that, for carbon dioxide, seem still out of reach and beyond our collective vision. Can we, for example, encourage and accelerate the transition to alternative sources of energy, sources other than fossil fuels, sources that produce little or no carbon dioxide? Some energy sources, such as nuclear power, produce no carbon dioxide but have other serious side effects. As you know, there are no U.S. nuclear plants now under construction, largely because people arc worried about reactor accidents and radioactive-waste disposal. A lot of people—I'm one of them—are concerned about these aspects of nuclear power.

I'm even more worried about the proliferation of weapons-sensitive plutonium. That's a problem you can't easily avoid using conventional

reactor technology. The global population today consumes commercial energy at the rate of about 10 terawatts, or 10 trillion watts. If you were to produce all that energy in conventional nuclear plants, you would need l0,000 plants, because it takes 1,000 plants to produce a terawatt. Each such plant produces about 1,000 kilograms of plutonium every year, and it takes only 10 kilograms to make a bomb. Just ponder those numbers if you think the risks are exaggerated.

So we must face the consequences of millions of kilograms of plutonium being produced as a by-product of generating electricity from nuclear fission. Even if the reactors are fail-safe, built from passively safe reactor designs—so that you can't possibly have another Chernobyl or Three-Mile Island accident—they still produce plutonium. And a terrorist is going to hold up a truck or a train one fine day and get hold of some. That's one of the most serious concerns.

Plutonium is also incredibly unhealthy. A millionth of a gram can give you lung cancer. It's one of the most toxic substances known.

But the nuclear-weapons-proliferation issue is even more serious than the other issues. If you could somehow figure out what to do with nuclear waste, and if you could control all the other problems, then you would still have to maintain iron control over all the fingers on all the potential nuclear triggers. You really have to worry about what might happen when you start shipping substantial amounts of weapons-sensitive plutonium around the world.

There is hope in the long term for certain alternative energy sources. Nuclear fusion, one of the most prominently mentioned of these, could, in principle, allow us to tap virtually inexhaustible energy supplies with few harmful side effects. But this is a hope for the relatively distant future, not a practical reality for the present. Fusion energy is not available today. We don't yet even see a clear way to achieve it. And there is a pressing need for alternative energy sources now.

In my opinion, and that of many scientists, renewable resources such as solar, wind, biomass, hydropower, and geothermal energy are by far the best near-term hope for reducing reliance on fossil fuels. These alternative energy sources are increasingly competitive and feasible on a large-scale basis, even considering the many subsidies and policies that artificially lower the price of fossil-fuel energy by concealing its true costs. Furthermore, many renewable technologies are rapidly improving in terms of price. Even today, they are often economically competitive with energy from fossil fuels and are sometimes significantly cheaper. In

general, the benefits of switching to renewable energy sources, like the benefits of improving energy efficiency, arc far greater than most people and governments realize, and far easier to achieve.

To date, the U.S. government, in contrast to some Western European governments, has generally taken the view that it's more prudent to conduct further research and to delay the changes in the economic and social system that might result from massive changes in the way we produce and use energy. This view assumes that the risk of economic and social disruption is greater than the risk of waiting.

Many knowledgeable scientists and energy-policy experts vehemently disagree. They arc convinced that an immediate and serious effort to reduce fossil-fuel use and initiate the transition to renewable energy sources is practical, economical, and in the best interests of the country, and the world.

To close on a bright note, we belong to a species that has an incredible capacity for invention and adaptation. Many things that arc taken for granted in the world today were unforeseen only a few decades ago. Once you recognize the nature of a problem, and once you convince enough people that there's something to be concerned about, you can initiate the process of coping with it. You can begin the transition to alternative energy sources, and you can start getting governments to think about how to reduce energy use and stabilize population.

There is of course a difference between knowing what must be done and bringing yourself to do it. Alternative energy paths arc not a futuristic dream. They are available and attractive today. The global potential for improved energy efficiency and energy conservation is gigantic. Obtaining energy from renewable resources is demonstrably practical now, not at some vague future time. Done intelligently, switching from fossil fuels often actually saves money rather than costing more.

Thus, the task is in very large measure a consciousness-raising matter, in much the same way that a binding international agreement to rid the world of CFCs followed from the realization on the part of people in many countries that they all had a stake in eliminating them. Coping with the enhanced greenhouse effect and climate change is of course not as technologically simple as stopping ozone depletion, which has a single cause. But the ozone-depletion story, demonstrates the resourcefulness that people and nations can bring to bear in facing a problem, once it has been recognized as a problem, by asking the right questions and provoking the right answers.