Scientists are predicting a dramatic rise in global temperatures

ROSS LAVER September 17 1990


Scientists are predicting a dramatic rise in global temperatures

ROSS LAVER September 17 1990



Scientists are predicting a dramatic rise in global temperatures

In the spring of 1938, a young univer+sity science student named Kenneth Hare attended a lecture at the headquarters of the Royal Meteorological Society in London. The speaker was George Callander, a British physicist who was trying to discover the cause of a gradual warming trend in Northern Europe and North America that meteorologists began observing in the 1880s. Callander speculated that the changes were caused by increased levels of carbon dioxide, a byproduct of fossil-fuel combustion that was preventing the sun’s heat from being reflected back into outer space. It was an idea that had been circulating among scientists for decades, but Hare said that few people in the audience that night seemed impressed. “I guess you could say we were inattentive,” recalled Hare, now 71 and chancellor of Trent University in Peterborough, Ont. “At the time, I don’t think anybody thought that the topic was all that important.”

Half a century later, however, the theory that manmade pollutants are heating up the atmosphere is at the centre of an intense scientific and political debate—and prodding many governments into action. Some of the world’s most eminent climatologists now predict that the average world temperature will rise by as much as 5° C by the middle of the next century—triggering widespread droughts, food shortages and sea-level rises severe enough to inundate many low-lying coastal areas. To avoid catastrophe, they say, mankind will have to reduce sharply its dependence on oil, coal and natural gas—the fossil fuels that are the primary energy sources of modern Western economies. On the other hand, some equally qualified skeptics maintain that the potential for global warming has been blown wildly out of proportion. They argue that there is not enough scientific evidence to justify making costly and wrenching changes in our current way of life.

Experts on both sides of the controversy say that it will take years, probably decades, before they settle the scientific arguments. But in spite of the uncertainties, a broad range of environmentalists and policymakers is calling for strong action now to limit emissions of “greenhouse gases”—principally carbon dioxide, but also methane, nitrous oxide and other chemicals that trap infrared radiation close to the Earth’s surface. Political leaders as diverse as Prime Minister Brian Mulroney, Britain’s Margaret Thatcher, Soviet President Mikhail Gorbachev and French President François Mitterrand have endorsed calls for an international treaty to stabilize the global climate. Declared Kirk Dawson, the low-key civil servant who oversees Canada’s research into global warming: “If we wait for science to prove that climate change is real, it will be too late. We have to start taking action now in order to buy some time.”

According to Dawson, the potential threat of global warming is unlike any other environmental problem mankind has faced. In an effort to curb acid rain, he pointed out, governments in Canada and the United States slapped restrictions on sulphur dioxide emissions by a handful of large mining companies and electrical utilities. Similarly, halting ozone deple-

tion will require a phase-out of chlorofluoroearbons, chemicals currently produced by only a few large companies (page 70). But the threat of global warming, if real, poses a vastly more difficult—and expensive— challenge. “For the first time, an environmental issue has come face-toface with the world economy,” Dawson said. “This is not something that is going to be solved by one or two large companies. Each and every one of us will have to get involved.”

Despite his initial skepticism, Kenneth Hare long ago joined the ranks of those calling for a reduction in the worldwide output of greenhouse gases. A climatologist, Hare began to take seriously the effects of manmade pollutants on climate after learning about the results of U.S.

studies in the late 1950s that confirmed that man’s use of fossil fuels was increasing the carbon dioxide content of the atmosphere. But in spite of the growing body of research on the subject, Hare said that, until recently, few Western climatologists displayed much concern about global warming. “I had a hell of a time trying to get people interested in climate change,” recalled Hare, who helped to organize the first World Climate Conference in Geneva, sponsored by the United Nations in 1979. “For many years, I felt like I was pushing a very large ball uphill.” Gradually, though, the scientific tide began to turn. During the 1960s and 1970s, U.S. scientists began trying to represent the changing atmosphere mathematically on computers. The computer models were at best crude simulations of the real world, and the results varied. But nearly every experiment concluded that doubling the amount of carbon

dioxide in the atmosphere would produce some warming, usually between 1.5° and 5.5° C, averaged over the surface of the Earth. In 1979, Canada responded to the growing scientific concern about global warming by establishing the Canadian Climate Centre, the suburban Toronto agency that Dawson now heads. Recently, the centre published the results of its own computer model. The model suggests that global temperatures would rise by an average of 3.5° C if carbon dioxide levels double (page 68).

But the real turning point for climatologists committed to the greenhouse theory occurred in 1988. That was the year that Toronto played host to a $ 1.6-million international conference on the Earth’s changing atmosphere, attended by 330 scientists and government officials from 46 countries. By coincidence or not—scientists argue strenuously about whether global warming has already started— 1988 was also the warmest year since scientists began keeping detailed weather records in the late 1800s. Across the Canadian Prairies and the U.S. Midwest, crops withered in the fields, rivers began to run dry and, in some communities, water shortages became routine.

Amid a barrage of media coverage, the delegates in Toronto endorsed a resolution calling for a 20-percent reduction in global emissions of greenhouse gases by the year 2005. “The Toronto meeting had a major impact,” Stephen Schneider, a climatologist with the U.S. National Center for Atmospheric Research, wrote recently in his book, Global Warming: Are We Entering the Greenhome Century? He added, “Because of media attention in 1988, the issue is now firmly in the front of public consciousness.” Despite that, scientists are a long way from resolving many of the key questions that surround climate change. And skeptics point out that existing computer models do a poor job of explaining previous changes in the world’s climate. Currently, the atmosphere contains about 330 parts per million of carbon dioxide, compared with 280 parts per million in the late

1800s. According to most of the models, that should have raised the Earth’s temperature by about 2° C.

In fact, the average global temperature has risen by less than half a degree since 1880—and some scientists believe even that increase may be part of the normal historical cycle of atmospheric warming and cooling. “On past performance, the models are off by at least a factor of four,” said Richard Lindzen, a meteorologist at the Massachusetts Institute of Technology in Cambridge, Mass., and a leading critic of the global warming theory. “Either the models are totally inaccurate, or something else is delaying the response.”

Lindzen and other greenhouse skeptics do not dispute that atmospheric carbon dioxide levels are rising and that the eventual result will be changes in the Earth’s climate. But they contend that any significant warming, if it occurs at all, will not take place for hundreds of years, in part because the oceans are capable of soaking up much of the excess heat that will be trapped in the atmosphere.

Lindzen, for one, said that even if carbon dioxide levels do double within the next 50 years—as many experts predict—it would

Percentage favoring construction of more nuclear stations to replace older plants that burn fossil fuels, by region. British Columbia:.........46 Prairies:........................53 Ontario-.........................62 Quebec:..........................45 Atlantic:.......................60

Percentage willing to drive less to reduce global warming: British Columbia-..........68 Prairies-.........................64 Ontario:........................62 Quebec:..........................58 Atlantic:.......................58


A recent study by the U.S. National Academy of Sciences concluded that global sea levels would rise by 1V2 to 3V2 feet in the next century. Among the countries most vulnerable to sea-level rise are Bangladesh, Egypt and Indonesia.


The federal environment department says that people can slow down the greenhouse effect by using energy more efficiently and by planting trees—each of which absorbs more than 45 lb. of carbon dioxide in a year.

Canada is considering joining West Germany, Sweden and the Netherlands with targets to cut carbon emissions

take another 300 years before the full effect of that change would be reflected in the world’s climate. “It goes without saying that fuels we will be using 300 years from now will be nothing like the ones we use today,” he said. “Frankly, I think this will go down as one of those occasional hysterias that years from now people will laugh about.”

Another common objection to the greenhouse theory is that scientists still do not understand the full range of climatic changes that would be set in motion by higher levels of carbon dioxide. Much of the confusion centres on the role of clouds. Scientists point out that a rise in temperatures should result in increased cloudiness, because warmer air is capable of absorbing more moisture. During the day, the additional clouds could offset the greenhouse effect by shielding the surface of the Earth from the sun’s rays. But at night, those same clouds could serve as a kind of atmospheric blanket, preventing heat from being radiated away. As yet, it is unclear whether the cooling effect of clouds

during the day would exceed the warming effect they would have at night. Nor is there any proof that global warming would lower overall agricultural production. On the contrary, higher levels of carbon dioxide would likely result in increased yields of some crops, because plants feed on carbon dioxide and expel oxygen. “I don’t disagree that the surface temperature of the globe is going to warm up, even if we do not know when and by how much,” said climatologist Patrick Michaels of the

University of Virginia. “But I mean, a smart person takes lemons and makes lemonade.”

Both Michaels and Lindzen contend that many of the environmental activists who claim to be concerned about global warming have an ulterior motive: their real aim is to discourage the use of fossil fuels. “These people have been pushing for better energy policies for years, only it hasn’t worked,” Lindzen said. “So now they’re trying to frighten

the public into doing what they want. I regard that as duplicitous and silly.” Added Michaels: “Global warming is an issue whose politics have greatly outrun its science.” Among scientists who profess to be worried about the greenhouse effect, Lindzen’s and Michaels’s arguments have provoked everything from thoughtful debate to anger. Originally, Hare told Maclean’s that Lindzen is “a first-class scientist.” Later, when he learned that Lindzen had accused greenhouse theorists of pursuing a hidden agenda, Hare’s tone became markedly less generous. “That’s an insult,” he said. “It is a terrible thing to say about a fellow scientist, but Dick Lindzen has not read the literature. There is a body of expertise that he and others appear to have ignored.”

Like Hare, most environmentalists are quick to reject Lindzen’s and Michaels’s conclusions. But some activists do concede that the scientific issues that surround climate change have more often than not been obscured by politics. Indeed, Hare said that some politicians in Canada and elsewhere seem to have spoken out about the dangers of global warming simply to attract publicity and gain support from environmentally concerned voters. “Obviously, there is a lot of opportunism and personal ambition behind the environmental rhetoric,” Hare added. “It’s damn disconcerting.”

But the argument that political concerns have played a role in the greenhouse debate almost certainly cuts both ways. For his part, Michaels said that he is worried that public fears about global warming will give rise to “extremely interventionist policies” such as higher fuel taxes and tougher restrictions on industrial pollution. Similarly, the pro-business U.S. magazine Forbes warned its readers recently that concern about the greenhouse effect could transform the U.S. Environmental Protection Agency into “the most powerful government agency on earth, involved in massive levels of economic, social, sei-

entific and political spending and interference.”

So far, President George Bush has resisted calls for concrete action to limit greenhouse-gas emissions, stressing the need for more scientific research. But Bush’s cautious approach to climate change has left him clearly in the minority. The list of countries that have already announced tough targets to cut carbon emissions includes West Germany, Sweden and the Netherlands, and Canada is considering following suit later this year. As Thatcher herself put it, such measures may be the best form of insurance against an uncertain future: “Even though this kind of action may cost a lot, I believe it to be money well and necessarily spent, because the health of the economy and the health of the environment are totally dependent upon each other.” The international momentum for a treaty to stabilize the atmosphere is building. Next month, the heads of scientific and environmental agencies around the world are scheduled to gather in Geneva to review the latest research on climate warming. A week later, government officials will meet in the same city to consider possible responses—measures that could include more efficient use of fossil fuels, greater investment in alternative energy sources and a worldwide campaign to replant and preserve forests.

Meanwhile, Bush has offered to host an initial meeting of government representatives in early 1991 to begin negotiations on an international agreement on climate change. “Personally, I believe that we can ride through this problem,” said Hare, who will lead a panel on climate research at the Geneva conference. “But the future will be a lot more difficult for us unless we start to take action now.” As Hare is the first to admit, the real challenge will be to find ways of mitigating the climate-warming problem that do not seriously damage the economy.



The question has nagged climatologists for decades: how does manmade pollution influence the Earth’s climate? To find the answer, scientists at Environment Canada turned to a $20-million supercomputer housed in a government office building in the Montreal suburb of Dorval. By feeding into the computer information about the Earth’s geography, soil moisture, the role of clouds and other factors, the scientists created a mathematical climate model. Next, they asked the computer what would happen if human activity caused a doubling of the amount of carbon dioxide in the atmosphere; most experts predict that carbon dioxide levels will double within 50 years, although they note that it would likely take a century or more for the climate to show the full effect of that change. The preliminary results suggest that average year-round global temperatures would eventually rise by 3.5° C. However, the warming effect would be stronger in the Northern Hemisphere, in part because the large amount of ocean south of the equator moderates changes in temperature. The computer-generated map (below) shows Environment Canada’s projections of the possible rise in temperatures across North America.