By the year 2030, the Earth's population is expected to increase to 10 billion; ideally, all would enjoy standards of living equivalent to those of present-day industrial democracies. However, if 10 billion people consume critical natural resources such as copper, nickel, and petroleum at the current per capita rates of industrialized countries, and if new resources are not discovered or substitutes developed, such an ideal would last a decade or less. Moreover, projections based on the current rate of waste production in many industrialized countries suggest that 10 billion people would generate enough solid waste every year to bury a large city and its surrounding suburbs 100 meters deep.

These estimates are not meant to predict a grim future. Instead they emphasize the incentives for recycling, conservation, and a switch to alternative materials. They also suggest that the traditional model of industrial activity, in which individual manufacturing processes take in raw materials and generate products to be sold plus waste to be disposed of, should be transformed into a more integrated model: an industrial ecosystem. In such a system the consumption of energy and materials is optimized, wastes and pollution are minimized, and the effluents of one process—whether they are spent catalysts from petroleum refining or discarded plastic containers from consumer products—serve as the raw material for another process.

Materials in an ideal industrial ecosystem would not be depleted any more than are materials in a biological ecosystem, in which plants synthesize nutrients that feed herbivores, some of which in turn feed a chain of carnivores whose waste products and remains eventually feed further generations of plants. A chunk of steel could potentially show up one year in a tin can, the next year in an automobile, and 10 years later in the skeleton of a building. Some manufacturers are already making use of "designed offal" in the manufacture of metals and some plastics: tailoring the production of waste from a manufacturing process so that the waste can be fed directly back into that process or a related one. Such recycling still requires the expenditure of energy and the unavoidable generation of some wastes and harmful by-products, but at much lower levels than are typical today.

The ideal industrial ecosystem, in which there is an economically viable role for every product of a manufacturing process, will not be attained soon; current technology is often inadequate to the task. However, if industrialized nations embrace major and minor changes in their current industrial practices and developing nations bypass older, less ecologically sound technologies, it should be possible to develop a more closed industrial ecosystem that would be more sustainable than current industrial practices, especially in the face of decreasing supplies of raw materials and increasing problems of waste and pollution.