Is The Ozone Hole In Our Heads?

IT STARTED SMALL-MAGAZINES CALLING attacks on disposable diapers "vigilante environmentalism." It grew bolder-industry claiming that inhaling some forms of asbestos poses no real danger, and that dioxin isn't the poison it's made out to be. Now the backlash against environmentalism is in full swing. In the latest assault, ecorevisionists have been filling books, op-ed pages and radio airwaves with attacks on what many scientists consider one of the most menacing global threats, and the one on the strongest scientific footing: depletion of the planet's protective ozone layer by chlorofluorocarbons (CFCs). In a typical broadside, Garbage magazine concludes in this month's cover story, "The real [ozone] crisis ... is our gullibility." Rush Limbaugh says that anyone who claims that CFCs destroy ozone is a "dunderhead alarmist."

The ozone backlash centers on two main points: CFCs do not destroy the ozone layer, which blocks dangerous ultraviolet rays; and even if ozone is thinning, that poses no threat to human health. The revisionism thrives because it sounds plausible, even to some scientists. Derek Barton, a Nobel Prize-winning chemist at Texas A&M, signed a petition calling for the repeal of the international pact phasing out CFCs. "There's so much propaganda [around the ozone issue] that I just don't believe it," he says. "But I haven't looked into it scientifically." Yet enlisting a Nobelist gives the skeptics credibility.

If experts can't agree, what's a layperson to think? A guide to the issues:

CFCs, the Pac-Men of ozone, are heavier than air, says zoologist Dixy Lee Ray, former chairman of the Atomic Energy Commission and author of this year's "Environmental Overkill." So they could never waft 30 miles up to where ozone protects the planet from UV rays. It's true that CFCs are five times heavier than air. But air movements mix heavy and light molecules. Since 1975, researchers have collected thousands of stratospheric samples-all with CFCs.

Chlorine from volcanoes and seawater entering the atmosphere dwarfs any ozone-eating chlorine from CFCs, say ozone skeptics. But this natural chlorine dissolves in water; most falls out as rain long before it reaches the ozone layer. CFCs, in contrast, are insoluble; they reach the stratosphere and stay there for decades. Ray also claims that the "1976" eruption of an Alaskan volcano spewed 570 times the world's CFC production; unfortunately, the blast occurred 700,000 years ago. Another popular line of attack holds that Mount Erebus, an Antarctic volcano. causes the infamous ozone hole over the South Pole. But Erebus sputters rather than erupts, so its chlorine falls out as rain before it reaches the ozone layer. Even ozone critic S. Fred Singer, of the Science and Environmental Policy Project, concedes, "Most, though not all, of the chlorine reaching the stratosphere is from CFCs."

Even if the Antarctic ozone hole is caused by CFCs, say critics, that doesn't mean anyone other than penguins has to worry. "The ozone hole is real and genuine," says Singer, "but you cannot prove from existing data that global ozone depletion [due to CFCs] has occur-red" anywhere outside Antarctica. Moreover, the measured 4 to 5 percent ozone loss over the last decade, and the 8 to 10 percent drop in winter, is swamped by seasonal variations in ozone of up to 40 percent, argues Singer. Atmospheric chemist F. Sherwood Rowland of the University of California, Irvine, calls that argument "disingenuous: the ozone changes over the Northern Hemisphere are outside the range of natural loss."

If ozone loss is a danger, everyone agrees that it's because the thinner the ozone layer, the more cancer-causing UV rays reach the planet. Revisionists say there is no evidence that more UV-B is coming through and, even if it is, the extra exposure would hardly be off the charts. "A 10% increase in UV-B ... would also be experienced moving 60 miles toward the equator," writes Singer. ut that's little comfort: the southward movement of the an population has helped kin-cancer rates.) And except for one set of suspect data, says Rowland, "we have seen increases in UV-B." Smog absorbs some UV-B, periodically hiding the effects of ozone loss, but when smog is factored in, more UV-B is reaching Earth. There is a 45 percent increase in UV over part of Argentina in the summer, for instance.

Who cares if skeptics pummel ozone science? After all, the global pact calling for the phaseout of CFCs by 1996 is unlikely to change. (Ozone loss will reach 10 percent or more around the turn of the century, estimates physicist Michael Oppenheimer of the Environmental Defense Fund. Then, thanks to the CFC ban, it will recover over the next 100 to 150 years.) Yet by calling ozone science a sham, ideologues have a better chance of derailing the next environmental treaty: to control gases that trap heat in the atmosphere. As early as this week, President Clinton might unveil his long-promised plan to scale back emissions of these greenhouse gases to 1990 levels by the year 2000. If the critics are right, the globe has little to worry about. But if they win the debate and are wrong, it will be too late for repairs.