The last Earth Day of the century was observed this week. Time to look back to 1970 when it all got started. What were the realities and. fears then – and what are they today?

Thirty years ago, the environment was not in such good shape. Air and water pollution were widespread – but were gradually getting better even before EPA came on the scene in December 1970. Rivers and lakes were polluted with poorly treated sewage. Too much in the way of nutrients produced eutrophication: Algal blooms and massive fish kills; lack of oxygen and lots of stink; the Cuyahoga River caught fire; Lake Erie was dying or dead, according to some. Air pollution had actually killed people in Donora, Penn., and smog was making people sick. Acid rain wasn’t yet recognized as a problem, but sulfur emissions were already beginning to decline in response to public pressure.

And what were some of the fears? DDT was supposed to kill off the plankton in the oceans, which was supposed to stop release of oxygen to the atmosphere, and we would all – gasp – die. Supersonic transport aircraft were supposed to chew up the stratospheric ozone layer and we would all die of skin cancer; so the program was canceled.

Nuclear safety was uppermost in people’s mind, the fear of dying from nuclear explosions or at least from radiation-caused cancer. So reactor construction was fought and delayed with lawsuits, requiring costly retrofits and making atomic power very expensive. And let’s not forget the 1971 National Academy report warning of a coming ice age and predicting an imminent glacial fate for the world.

There was indeed a rich menu of disasters to choose from. By 1972, the Club of Rome study added depletion of resources: The world would run out of oil, metals, land and food before the end of the century; it made big news. Professor Paul Ehrlich preached zero population growth and predicted mass starvation, a dying ocean, cancer epidemics, and massive die-offs in cities because of air pollution all within a decade.

Today, these old fears seem quaint. How could anyone have believed them? But we now have new ones to take their place.

In 1970 also, Sen. Ed Muskie, Maine Democrat, was competing against Richard Nixon, to see who could be more environmentally correct. The National Environmental Policy Act begat impact statements and the EPA. Mr. Muskie’s Clean Air legislation managed to cripple the American automobile industry by requiring too much, too soon. (When oil prices tripled a couple of years later, Detroit nearly went out of business.) Finally, by 1974, the National Academy of Sciences produced a multivolume cost-benefit study that {surprise, surprise!} backed up Mr. Muskie –who had authorized the report through EPA. The study accomplished that goal by omitting important cost items, like inspection and enforcement, and by computing the benefits in two different ways and then adding the two numbers.

After this double-counting exercise, the total benefits became "commensurate" with the costs. (Almost) everyone seemed pleased with the outcome and hardly anyone questioned Mr. Muskie’s automobile emission limits.

Today, after the nation spent tens of billions or perhaps hundreds, the environment is in great shape. Rivers are flowing clean, with salmon returning to New England and to the Hudson. Smog is mostly gone except in a few cities like Los Angeles. We don’t hear much about acid rain. Oil is plentiful and cheap too cheap, some would say. Nuclear plants are running well; the several accidents that were predicted to happen haven’t happened. Disposal of spent nuclear fuel is a PR problem not a technical one. There is no world famine and population growth around the globe is slowing down.

But we now have lots of environmental organizations, whose existence depends on creating new fears. And EPA feels compelled to justify its ever-expanding budget. So here goes:

Pesticides and radiation fears are still going strong, with EPA stirring the pot on radon, secondhand smoke, and chemicals. Since cancer epidemics cannot be demonstrated, the catchword is "hormonal disrupters." No evidence for this, of course, except a research paper that was withdrawn after no one could reproduce its results. So it’s back to global disasters, much more fashionable and exciting than worrying about real problems, like how to dispose of growing piles of garbage.

Ozone depletion no longer seems as threatening as it did seven years ago, when CFC production was banned (in industrialized countries). I suppose that’s because no one has ever observed the increase in solar ultraviolet radiation that was supposed to lead to epidemics of skin cancers.

So now we have the fear of climate change. Al Gore, known as the "ozone man" a decade ago, is now hyping global warming, along with much of the media establishment and even some of the science crowd. The federal government is pumping $2 billion a year into global change research, but the atmosphere is not playing along. No warming trend is seen by weather satellites. And to make matters worse, a respected team of economists has just demonstrated that global warming would actually be good for you. But we have known this from the history books.

The last word on this topic belongs to the late Professor Aaron Wildavsky, who correctly typed global warming as "the mother of all environmental scares."

Will it still be there 30 years from now or will we dream up new hobgoblins to frighten the populace in surrendering their money and freedom to government regulators and international inspectors?