Air pollution is not merely a nuisance and a threat to health. It is a reminder that our most celebrated technological achievements-the automobile, the jet plane, the power plant, industry in general, and indeed the modern city itself-are, in the environment, failures.

In every case, the environmental hazards were made known only by independent scientists, who were often bitterly opposed by the corporations responsible for the hazards.

If you ask what you are going to do about global warming, the only rational answer is to change the way in which we do transportation, energy production, agriculture and a good deal of manufacturing. The problem originates in human activity in the form of the production of goods.

Finally, since human beings are uniquely capable of producing materials not found in nature, environmental degradation may be due to the resultant intrusion into an ecosystem of a substance wholly foreign to it.

In nature, no organic substance is synthesized unless there is provision for its degradation; recycling is enforced.

Perhaps the simplest example is a synthetic plastic, which unlike natural materials, is not degraded by biological decay. It therefore persists as rubbish or is burned-in both cases causing pollution. In the same way, a substance such as DDT or lead, which plays no role in the chemistry of life and interferes with the actions of substances that do, is bound to cause ecological damage if sufficiently concentrated.

The environmental crisis is a sign that the ecosphere is now so heavily strained that its continued stability is threatened. It is a warning that we must discover the source of this suicidal drive and master it before it destroys the environment-and ourselves.