Peter Huber is the author of Hard Green: Saving the Environment from the Environmentalists (Basic Books 2000), and a senior fellow of the Manhattan Institute for Policy Research.

The rich are ruining the planet. A mere 5% of the world's population lives in the United States, but Americans consume 20% to 40% of "resources" -- fossil fuels, electricity, copper, aluminum, zinc and so forth. If the rest of the world lived as we do, it would take "two planet earths" to feed and fuel it. Or so we are often told. But the facts -- the important ones -- show otherwise.

The difference between rich and poor

Our pioneer ancestors leveled some 200 million acres of North American forest for farmland and pasture. Since 1920, however, we have been reforesting the continent. For at least a century, now, the average American has eaten more food, and consumed more energy, even as the American farmer has plowed fewer acres and harvested less wood. The result has been an extraordinary environmental renaissance on our continent.

What happened? Quite simply, we learned to live in three dimensions, not just two. We learned to draw less of our wealth from the living surface of the planet, and more from its sterile depths. Cement, steel and synthetic plastics displaced hardwoods in our ships, dwellings and furniture, leaving the wood itself to the forest. Fossil and nuclear fuels displaced wood in our residential and industrial furnaces. Fertilizers, pesticides, factory farms and high-yield crops from the laboratory substituted, at the margin, for some three-quarters of the acres once needed to produce equivalent amounts of food. By extending human enterprise into the third dimension, we have painlessly retreated from the two-dimensional surface, where the rest of life dwells.

Poor countries are horribly bad at conservation because they lack the capital and know-how that we have put to such good use. For the poor, the elephant remains a mountain of meat, the whale is a barrel of oil, and the rain forest is a place to grow cassava, once the monkeys have been shot and the undergrowth cleared by fire. Despite their small appetites, developing-world countries manage to generate a lot of garbage, smoke and trash. They consume little, but they are wasteful and destructive. They use no pesticide and plow more land; they use no plastics and discard far more organic waste; they eat little meat and shoot more elephants.

What it takes

Moving our Western economy into the third dimension has required one input above all others: capital. It takes vast amounts of it to extract oil from two miles beneath Alaskan ice or Saudi sand, or to process the oil into plastics that then displace teak and ivory, or to reconfigure the genes that quadruple yields on the farm. From wood to coal to oil to uranium, the higher the technology the more capital it requires to burn it, and the less natural resource.

Resource is not what we get,it's knowing how to get it

The second crucial input to the three-dimensional economy has been knowledge. The mystery is not why we consume so many resources so fast -- from so deep in the earth ¿ it is why thousands of generations of shivering, starving humanity left so much wealth untouched. And it is not much of a mystery, at that. Oil two miles beneath Alaskan ice or Saudi sand is not "wealth" at all. It does not belong to anyone, least of all to "the world." We call such things "resources" by convention, but the "resource" is not the stuff itself; it is knowing how to get it. Anyone can gather wood and burn it -- man has been doing that successfully for tens of thousands of years. Gathering and burning uranium is much harder, but a tiny volume of it, prepared just so, can heat and light an entire city.

The happier Third World economies today are what ours were 50 years ago; the unhappier ones are what ours were some centuries earlier. Why should we expect them to be green? We weren't when we were as poor as they are. Victorian England is not a shining example of environmental rectitude for modern London. Buffalo Bill was not a paladin of wise husbandry on the American range. We have no reason to be proud of our own environmental past -- which is, by and large, the Third World's environmental present.

Finally, it is wealth -- not poverty -- that is now ending the sprawl of humanity itself. Developed-world fertility has been falling quite steadily for two centuries. In the United States, it dropped from eight children per woman to two. In what the United Nations calls the "more developed regions," the "total fertility rate" (roughly speaking, the average number of children born per woman) has fallen from 2.8 children per woman in the 1950-55 time frame to 1.6 today. That puts it well below the replacement rate. Exactly the same is now happening in developing countries as they grow wealthier. The fertility rate in India today is lower than the American rate in the 1950s. Fertility rates in most sub-Saharan African nations are falling steadily.

Parents everywhere, it turns out, respond to a simple equation: Wealth permits them to raise fewer, more robust children. Producing food abundantly, in other words, is a highly effective way to limit population. But this sequel to the Malthusian story, in which humanity halts its own genetic sprawl, takes time to play out. For most of the last two centuries, mortality rates were dropping faster than fertility rates, so population grew. But in this century, mortality and fertility came into balance. Populations in the developed world have now stabilized. They will soon begin to shrink. If the trajectories of rising global affluence and falling fertility stay on their present course, world population -- about 6 billion today -- will peak at about 10 billion in 2050, and will then start shrinking.

The real meaning of green

Green is what people become when they feel personally secure, when their own appetites have been satisfied, when they do not fear for the future, or for their own survival, or their children's. It is wealth that gives ordinary families the confidence to be generous to the world beyond. It is the rich who can be thin because they know they will always have plenty to eat. It is the rich who can cherish the wilderness because they no longer have to choose between their own survival and nature's.