Living Under an Angry Sun
News about the thinning ozone layer is anything but cheerful, but there are steps you can take to help
Citizens of the world, welcome to the Uh-Oh Zone. The alarming erosion of our planet's ozone layer may not kill us, but it is altering the way many of us think about the outdoors. Dire forecasts of skin cancer, cataracts and other threats to health, all caused by unfiltered solar radiation streaming in through our damaged atmosphere, are making the old phrase "fun in the sun" sound more and more like a prescription for misery.
Early this year, a modified U.S. spyplane named the ER-2 brought home some of the most disturbing evidence to date that our planet's protective ozone shield is in jeopardy. Flying over northern New England and eastern Canada, the spy-plane detected the greatest concentration yet found of an ozone-eating chemical. The atmosphere's "immune system" was in worse shape than experts suspected, Harvard University chemist James Anderson said at a briefing. "None of the news is good."
It hasn't been good for a while. A United Nations Environment Program report says a 10 percent ozone decrease will bring up to 1.75 million additional cases of cataracts every year throughout the world; the same ozone decrease will cause a 26 percent rise in nonmelanoma skin cancers, or an additional 300,000 cases a year. Ozone thinning threatens our crops, trees in our forests and plankton that supports the ocean food chain. No wonder Sherwood Rowland, the chemist who sounded the first ozone alarms back in 1974, is reported to have said, "Our research is going very well. Unfortunately, it may mean the end of the world." (There are, however, steps you can take to protect your health and that of the ozone layer; see box at right.)
The culprits in this crime against the atmosphere--well known but still at large--are a group of otherwise useful compounds called chlorofluorocarbons, or CFCs. Employed in everything from automobile air conditioners to cleaning solvents, CFCs have long been praised for their chemical stability. But that same stability means that escaped CFCs persist in the atmosphere for decades. Wafting into the stratosphere, 7 or more miles up, the compounds finally break down. But as CFCs disintegrate, they release chlorine atoms that destroy ozone molecules. The ozone destruction allows unhealthful amounts of ultraviolet radiation (UV) to reach the Earth's surface--bad news for sun worshipers.
We know very well that ultraviolet radiation causes skin cancer," says John Di Giovanna, an investigator in the dermatology branch of the National Cancer Institute. And while the nation's rising rate of skin cancer (at more than 600,000 cases a year, it is the most common cancer) can be blamed on factors like an increase in outdoor activities, destruction of the ozone shield is expected to boost disease statistics in years to come. Does that mean an end to safe tanning?
"Yes," says Benjamin Yokel, chief resident of dermatology at Johns Hopkins University Medical Center. "Any ultraviolet light that you expose yourself to willingly is an unnecessary risk."
But an angry sun means more than waning enthusiasm for the nut-brown lifeguard look. Harmful solar radiation is also believed to suppress the human immune system. Speaking to a Senate Committee last fall, Margaret Kripke, head of the immunology department at M.D. Anderson Cancer Center in Houston, warned: "Any factor that reduces immune defenses, thereby increasing the incidence or severity of infectious diseases, is likely to have a devastating impact on human health."
University of Maryland botanist Alan Teramura provides evidence of a thinning ozone layer's threat to forests. He has found that UV radiation can reduce a tree's ability to perform photosynthesis and can curb tree height and mass. Loblolly pine, mainstay of southern pine plantations, is among the most UV-sensitive of more than a dozen conifer species Teramura has studied. He has also learned that UV radiation affects crops like soybeans. The botanist believes a 25 percent depletion of ozone can result in a 20 to 25 percent reduction in soybean yield--"almost a one-to-one reduction," he says.
Teramura is concerned about effects of ozone depletion on wild, native plants. Plantation pine growers can conceivably develop plant strains more resistant to harmful radiation. "But you're not going to breed for a UV-tolerant oak-hickory forest," he says.
Researchers probing Antarctic seas have found equally disturbing evidence of our thinning ozone shield's toll on other life. Sampling single-celled algae during the (now predictable) annual thinning of the ozone layer over Antarctica, biologist Barbara Prézelin of the University of California, Santa Barbara, says she and colleagues found "the productivity of plants inside the ozone hole was about 10 percent less than outside the ozone hole."
Algae losses could mean trouble for krill, tiny animals that feed on the plants, and that themselves are food for other species. "Some people think the ozone hole was created by scientists to keep funding coming," says Pr6zelin. "But this is reality."
Most nations have agreed to stop use of CFCs by the year 2000. In February, President Bush announced that the United States will halt production of CFCs by December 31, 1995. But even with such measures, the world's enormous bank of still-escaping CFCs guarantees that ozone depletion--and scary sunshine--will be a worry for us deep into the coming century.
That leaves time to ponder whether we will act more quickly when faced with other environmental menaces. Sherwood Rowland, for one, thinks he knows the answer. Even now, notes the University of California chemist who 18 years ago predicted that CFCs were ticking bombs, some political leaders demand absolute proof of phenomena such as global warming before taking action. "The lesson is not very encouraging," says Rowland. "Faced with predictions of serious environmental problems, we will wait."
Wait, and watch, as the sun, symbol of light, warmth and of life itself, unveils its new and angry countenance.
Michael Lipske is a senior editor of this magazine.