During the past century, average global temperatures have gradually increased by about 0.5°C. Some scientists speculate that natural climatic rhythms have caused the warming trend and that the planet will eventually become cooler. But most climatologists—including Henry Hengeveld, a Toronto-based adviser to Environment Canada’s Canadian Climate Centre—now argue that the reverse is likely. In fact, Hengeveld and other experts predict that global temperatures will rise even more quickly over the next 40 years—by as much as another 5°C. They base their argument on the socalled greenhouse effect, a theory that holds that gases produced by industrial activity are accumulating in the Earth’s atmosphere and trapping heat. And, according to Hengeveld, there is new evidence to bolster the theory: scientists have established that last year was the warmest on record—and that in the 137 years for which records exist, the four warmest years all occurred after 1980. Said Hengeveld: “Something appears to be happening here that is unnatural.”
As a result, scientists around the world are expressing renewed concern about the potentially catastrophic consequences of the greenhouse effect— and are initiating efforts to halt it. According to the theory, carbon dioxide, a gas produced by the burning of such fossil fuels as oil and coal, and the emissions of chlorine-based gases known as chlorofluorocarbons (CFCs), which are found in aerosol sprays and refrigerants, act like panes of glass in a greenhouse—allowing solar radiation to penetrate the Earth’s atmosphere but preventing heat from escaping back into space.
Recent Canadian government studies suggest that if the warming trend remains unchecked, by the year 2030 the oceans would expand, causing permanent flooding in such vulnerable coastal cities as Charlottetown. At the same time, increased evaporation from the Great Lakes would dramatically lower water levels, forcing shippers to decrease their loads and increasing their costs by about 30 per cent.
In an attempt to avert such disastrous events, scientists and politicians from 37 countries are gathering for a four-day conference in Toronto later this month. Their objective: to seek strategies for addressing such problems as climatic change and ozone depletion. It follows an earlier effort—at a Montreal conference last September—to reduce CFC emissions. Scientists also link those gases to a decrease in the Earth’s ozone layer, an atmospheric shield of bluish gas that protects the planet from more than 90 per cent of the sun’s dangerous ultraviolet rays—which have the potential to destroy all life on Earth. Representatives from 24 countries—including Canada-signed a treaty in Montreal that committed the world’s industrialized nations to reduce the use of CFCs by 50 per cent by 1999. And, on June 2, the federal government announced that it would initiate regulations that would go beyond the terms of the treaty by banning all CFCs except such essential ones as those used in aerosols that propel medications.
Even in the unlikely event of immediate and massive cutbacks in the burning of fossil fuels, climatologists say that global temperatures are still almost certain to rise by a further 0.9 °C by the year 2030. That is because the world’s oceans store heat for long periods of time. Said Hengeveld: “The risks are great enough that we cannot wait to act.” Still, he added that he was encouraged by the increasingly serious attitude of both scientists and politicians to the theory—and dire implications—of the greenhouse effect.
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