Since scientists discovered a hole in the Antarctic ozone layer four years ago, that rip in the stratospheric fabric has become a dramatic symbol of growing concern about the Earth’s atmosphere. Last week, when scientists and government officials from around the world met in Toronto for a conference on the atmosphere, they had alarming new evidence to consider. Canadian scientists have discovered that a similar hole is developing in the Arctic ozone layer.
Ozone reduction exposes humans to increased doses of cancer-causing ultraviolet (UV) radiation from the sun. And, as a result, 24 nations agreed at a meeting in Montreal last September to cut back on the production of chlorofluorocarbons (CFCs), chemicals that are present in aerosol propellants and refrigerator coolants—and that are blamed for destroying ozone. But in Toronto, Robert Watson, a senior scientist with the U.S. National Aeronautics and Space Administration, said that scientists “may have underestimated the impact of CFCs.” He added, “Even if there is a substantial reduction in CFCs, the ozone hole will be here for at least 50 years.” But damage to the Earth’s protective ozone belt was only one of the indications of atmospheric upheaval that confronted the 330 delegates from 46 countries.
In four days of deliberations, scien-
tists discussed topics ranging from acid rain to environmental threats in the Arctic (box). But the so-called greenhouse effect—the growing threat of global overheating brought about by concentrations of manmade carbon dioxide and other pollutants in the atmosphere-emerged as the dominant topic. Until now, most scientists stopped short of tracing the severe drought afflicting parts of Canada and the United States to the greenhouse effect. But Canadian climatologist Kenneth Hare told the conference that “the greenhouse effect has shown itself,” adding, “We are indeed witnessing the beginning of the process.”
Norwegian Prime Minister Gro Harlem Brundtland called for a “coalition of reason” by governments to confront threats to the atmosphere. Brundtland added in her keynote address to the conference that the decay of the atmosphere “may be greater than any other—with the exception of the threat of nuclear war.” Scientists now predict that unless governments initiate steps to reverse the greenhouse process, the buildup of carbon dioxide from the burning of such fossil fuels as oil, natural gas and coal—as well as other pollutants-will make the surface of the planet between 1.5 °C and 4.5 °C warmer by about the year 2030.
Such an increase could raise sea levels
by as much as several feet and flood low-lying cities and land, cause inland waters to recede and turn agricultural land in some areas—including parts of the Canadian Prairies—into desert. Most scientists say that mankind could adapt and survive the change. But Hare, who is also the chancellor of Trent University in Peterborough, Ont., told the conference—which Environment Canada staged at a cost of $1.6 million—that if governments ignore the consequences of environmental changes, one result could be “the eclipse of the species.”
At the same time, evidence that a hole may be developing in the Arctic ozone layer alarmed scientists. Canadian researchers began investigating ozone levels in the stratosphere—an atmospheric layer that is located between six and 22 miles above the Arctic—in 1986 after studying earlier U.S. data on Antarctic ozone depletion. Wayne Evans, a senior experimental scientist with Environment Canada, said that by examining NASA satellite photographs of the region, scientists could see that a distinct crater-like gap had developed in the Arctic ozone layer during the late winters of 1982, 1984 and 1986. Since then, for reasons that scientists do not understand, the hole has been less pronounced. “My personal suspicion,” said Evans, “is that the Arctic ozone hole is about five years behind the Antarctic
hole. We’re going to see the Arctic hole develop quite strongly in the future.”
Scientists are already expressing concern about the danger posed by such disruptions to those ozone levels. In a complex interplay, increased methane production on the planet is raising ozone levels in the region of the atmosphere known as the troposphere — from ground level to about eight miles above the Earth—at the same time that the higher, stratospheric ozone is being depleted. Although researchers suspect that tropospheric ozone may cause respiratory diseases in human beings, stratospheric ozone depletion can cause skin cancer by letting through too much ultraviolet light.
As well, Lester Grant, director of environmental criteria for the U.S. Environmental Protection Agency, told the conference that evidence suggests ultraviolet rays may interfere with the human immune system, making people more susceptible to such infectious diseases as herpes and leprosy. Grant said that the biological processes involved bore some similarities to AIDS. Still, added Grant, “I don’t think anyone is in a position at this stage to say that increased uv radiation is responsible for AIDS.”
In the search for solutions to the looming crisis in the atmosphere, a final conference statement called for
strong measures, including a 20-percent reduction in carbon dioxide emissions by the major industrial nations by the year 2005. As well, the conference called for the development of a global legal framework to protect the atmosphere and proposed that an
international agency be established to tax fossil-fuel consumption. Some experts expressed optimism that the targets for reduced energy consumption could be met. But others said that they were less hopeful about the willingness of the major industrial
nations to cut back voluntarily on energy use. “I think we are in for a rough ride,” said Hans Martin, a Toronto-based senior adviser for Environment Canada. “But I don’t think we should think of this problem as so large that we just have to grit our teeth and watch it happen.” Inevitably, efforts to save the atmosphere will involve painful tradeoffs between economic growth and environmental safety. And as delegates met in Toronto, local politicians were embroiled with those very issues. After deciding in May to close an outmoded garbage incinerator that was discharging dioxin and other dangerous chemicals into the air, Metropolitan Toronto council gave the incinerator a temporary reprieve. The reason: officials at Toronto’s Lester B. Pearson airport, who had been unable to find an alternative method of disposing of leftover food and animal waste, faced the prospect of ordering international flights not ^ to serve meals before
0 landing in Toronto. That
1 small municipal drama only served to underscore the difficulty of the decisions that lie ahead as scientists monitor the Earth’s polluted envelope of air—and anxiously watch the polar regions for signs of further damage to the planet’s precious supply of ozone.
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