"The ozone layer, which protects living things from the Sun's harmful ultraviolet rays, has been depleted in many areas of the globe, and at the latitudes of the United States the loss is proceeding twice as fast as scientists had expected, the [U.S.] Environmental Protection Agency announced [in April].
"The agency said the declines measured in the late fall, winter, and early spring amounted to 4.5 to 5 percent in the last decade.
"'It is stunning information,' William K. Reilly, the agency's Administrator, said in an interview after the announcement in Washington. 'It is unexpected, it is disturbing....'
"According to agency calculations based on the new ozone findings, over the next 50 years about 12 million Americans will develop skin cancer, and more than 200,000 of them will die. Under previous assumptions, only 500,000 cancer cases and 9,300 fatalities were forecast....
"Scientists say that for every 1 percent decline in the high-altitude ozone shield, 2 percent more ultraviolet radiation reaches the earth's surface. Besides skin cancer, the harmful ultraviolet radiation can cause eye cataracts. Scientists say it can also affect the human immune system adversely, that it harms the ability of phytoplankton, tiny plants at the basis of the oceanic food chain, to reproduce; that it can damage some crops and wild plants." --NEW YORK TIMES April 5, 1991, pg. 1, D1.
Thus readers of the NEW YORK TIMES in April learned that ozone depletion is now proceeding rapidly in the atmosphere above the United States. For roughly 450 million years, the ozone shield--10 to 30 miles high in the sky--has protected the surface of planet Earth from ultraviolet radiation streaming in from the sun. Now chemicals called CFCs, released from refrigerators and air conditioners, are wafting upward, destroying the protective ozone in the stratosphere, allowing ultraviolet light levels to increase on the surface of the Earth. In sufficient quantities, ultraviolet light is a potent disinfectant, killing everything it strikes.
And so a problem that only three years ago seemed confined to an ozone "hole" over the ant arctic is now recognized as a world-wide calamity that will cause skin cancer in caucasians, will cause eye cataracts and immune system disorders in humans of all races, will interfere with the most fundamental underpinnings of oceanic food chains, and will disrupt wildlife reproduction in other ways that are poorly understood. Furthermore, the problem is developing twice as rapidly as scientists had predicted just last year, indicating that scientists--15 years after the National Academy of Sciences in Washington, DC, declared this a serious problem worthy of urgent attention--do not yet understand the problem sufficiently well to predict its course correctly. In this business of dismantling the life-support systems of the Earth, we are learning as we go.
Just this year, scientists seem to be reaching agreement that ozone loss is connected to another worldwide phenomenon that was first noticed in 1989. Scientists have reported simultaneous wildlife losses in places as far apart as California, Australia, Brazil, and Europe. It may sound silly at first, but amphibians--salamanders, toads, and frogs--are declining, disappearing, and becoming extinct at unprecedented rates world-wide. Increased ultraviolet light is now thought to be one important cause, though by no means the only one.
Dr. Henry Wake, a biologist from University of California at Berkeley chaired a panel of 20 experts for the National Research Council (Washington, DC) in early 1990. Dr. Wake compares the loss of frogs to the 19th-century coal miner's canary--when the canary died, it was a warning sign that the air in the mine had grown hazardous to humans. So with frogs, says Dr. Wake: "If frogs and salamanders are dying off in synchrony [at the same time], there's a message there for us," says Dr. Wake. (NY TIMES Feb. 20, 1990, pg. C4; SCIENCE NEWS Feb. 24, 1990, pg. 116, and March 3, 1990, pg. 142.)
The truth is, amphibians are rapidly disappearing from many ponds, rivers, mountains, and rain forests around the world, including places that are not very polluted. Dr. Wake says, "They are disappearing from nature preserves in the most pristine sites of Costa Rica, Brazil, Yosemite, Sequoia and Ile Royale National Parks [in the U.S.]. Meadows where frogs were as thick as flies are now silent," he says.
Individual scientists had been noticing the decline of frogs but it wasn't until 1989 that they compared notes at a global conference and discovered that reports of local losses were coming in from all over the world. Some scientists had refrained from reporting their observations of loss and extinction for fear that younger colleagues, or even children, would find live specimens of frogs reported extinct.
All the reasons for the decline of amphibians are not understood. In some cases, it's loss of habitat. Frogs that used to live in Japanese rice paddies now find golf courses instead. In the U.S., frogs return to ponds only to find condominiums. Stocking lakes and ponds with edible fish, particularly in the western U.S., wipes out frogs when fish eat their tadpoles.
But there's something going on besides direct human intervention. Dr. David Bradford of UCLA reports that in the 1970s he found ponds in the High Sierras containing more than 800 adult yellowlegged frogs and 1500 tadpoles. In 1990, he checked 38 lakes and found frogs in only one.
A leading cause of such declines may be acid rain and acid snow. The spring thaw brings a shock of acid water into mountain streams, killing sensitive creatures in the early stages of life.
Another source of problems is pesticides, including those that are banned for sale in the U.S. but which are still manufactured here and shipped overseas. Many of them, sprayed abroad, travel on the wind and rain down on U.S. soil; some see in this an ironic and fitting gift to us from the developing world, but for frogs and salamanders it represents apolitical destruction and death.
Amphibians are particularly sensitive to chemical pollution because they spend part of their life-cycle on land and part immersed in water; furthermore, they breathe through their skin. Toxic heavy metals and pesticides building up in aquatic food chains, plus a hefty dose of air pollution may be what's killing some frogs, toads, and salamanders.
The latest information is that many researchers now believe that increased ultraviolet radiation may be affecting frogs' eggs, which float on the surface of the water, absorbing sunlight. Too much ultraviolet light evidently interferes with the ability of egg cells to multiply.
What are Humans Doing About It?
The International Union for the Conservation of Nature (IUCN) has recently set up a "Task Force on Declining Amphibian Populations," located in Corvallis, Oregon. They are developing a worldwide network of scientists who will document the destruction of amphibians as the ominous global trend unfolds. (SCIENCE Aug. 2, 1991, p. 509.)
Back in Washington, President Bush has steadfastly refused to force an aggressive phase-out of ozone-depleting chemicals. Furthermore, Mr. Bush and Vice-President Quayle recently announced they are reversing U.S. policies established to protect wetlands. Under pressure from some of the nation's wealthiest lobbyists, the Home Builders Association, Mr. Bush will open millions of protected wetlands to development. (NY TIMES Aug. 3, 1991, pgs. 1, 25.)
For its part, DuPont, the company that invented, patented, and
sold the CFCs that are bringing ruin to the Earth, has developed
only one problem in recent years: managing all the money that is
pouring in. As CFCs are slowly phased out, they become scarcer
and their price is rising on the world market. Organizations
dependent upon refrigeration are willing to pay the rising cost
of CFCs to maintain their operations, and thus DuPont is reaping
literally billions of new dollars each year in windfall profits.
(NY TIMES April 21, 1988, pg. 2F.)
--Peter Montague, Ph.D.
Descriptor terms: ozone layer; global environmental problems; epa; reilly; studies; immune system; skin; cancers; eyes; oceans; food chain; habitat destruction; cfcs; nas; amphibians; wildlife; costa rica; brazil; yosemite; sequoia; ile royale; national parks; conferences; japan; rice paddies; heavy metals; air pollution; iucn; bush administration; wetlands; home builders association; dupont;