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IS THE WORLD REALLY COMING TO AN END? I began a talk at American University recently by asking how many in the audience believed that we face an imminent global ecological crisis. As a science reporter who frequently speaks on college campuses, I wasn't surprised that all the students raised their hands. I once believed that too. A generation ago brown smog clogged the air over many American cities, and Lake Erie was dying. I remember my high-school band trip to George Washington's home in Mount Vernon, Va. A sign in the Potomac River warned that contact with the water could be hazardous to your health. As a college student in the early 1970s, I read the experts who claimed that we were poisoning the biosphere, running out of resources and would soon be choking to death on pollution. The future seemed bleak. Yet some 25 years later I look around and, by and large, things have gotten better, not worse. Pollution is still a problem, but the air is much cleaner. Since 1975, sulfur-dioxide levels are down roughly 50 percent, carbon monoxide about 60 percent and smoke, soot and other particulates have been reduced some 25 percent. Water quality has also improved. The warning sign in the Potomac has been taken down. What hasn't changed are predictions of doom. Here are six popular visions of the apocalypse you may be hearing about. The evidence shows they are not true. 1) THERE ARE TOO MANY MOUTHS TO FEED. Thirty years ago biologist Paul Ehrlich predicted in The Population Bomb that "in the 1970s hundreds of millions of people are going to starve to death." Overpopulation, he claimed, would overwhelm the food supply. It didn't happen. World population has more than doubled since 1950, but food supplies have more than tripled. Life expectancy has risen from 46.5 years in 1950 to more than 64 years today. This represents the greatest increase in human welfare in history. If current trends continue, world population could top out at around eight billion in 2040. Can all these people be fed? Yes, says Paul Waggoner, a scientist at the Connecticut Agricultural Experiment Station. He estimates that if technology continues to improve at today's rate, it will be possible to feed ten billion people on roughly the same amount of land currently devoted to agriculture. As a result of improving crop yields, the area that is used to grow crops-about three billion acres globally-has increased little in the last two decades. 2. MAN-MADE CHEMICALS ARE CAUSING A CANCER EPIDEMIC. This notion became popular after Rachel Carson published the environmental classic Silent Spring in 1962 "For the first time in the history of the world," she asserted, "every human being is now subjected to contact with dangerous chemicals from the moment of conception until death." Her assertion is not true. "The vast bulk of the chemicals humans are exposed to are natural, and for every chemical some amount is dangerous," note Bruce Ames and Lois Gold, cancer |
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researchers at the University of California at Berkeley. Ames and Gold point out that "99-99 percent of the pesticides we eat are naturally present in plants to ward off insects and other predators." For example, many fruits and vegetables contain caffeic acid, peanut butter contains aflatoxin, and white bread contains furfural. All are natural carcinogens but should not scare people into giving up these foods. In addition, the human body's "defense enzymes are equally effective against natural and synthetic chemicals," according to Ames and Gold. What about the cancer epidemic? "It's not real," says Ames. While rates of certain cancers (especially those connected to tobacco) have risen over the past few decades, the rates of many cancers have declined in the United States since 1950. Plus, the increase in the number of detected cancers is due mostly to better diagnostic techniques. An article published last year in Scientific American estimated that only about two percent of cancer deaths in the United States are caused by pollution -and that more cancer is caused by lack of exercise. 3) MEN ARE BECOMING STERILE. In a recent book, Our Stolen Future, zoologist Theo Colbom warned that synthetic chemicals in the environment may be responsible for worldwide declines of 50 percent in human sperm counts over the last half-century. Among the chemicals she names is the pesticide DDT, which "disrupts the endocrine system." However, leading scientists do not accept as fact that sperm counts are declining. Rates of infertility in the United States, noted Dr. Richard Sherins in the New England Journal of Medicine, "have remained constant during the past three decades." Moreover, levels of some of the suspect chemicals have been dropping for decades. For example, one 1991 report indicated that concentrations of DDT in human fatty tissue fell from about eight parts per million (ppm) in 1970 to about two ppm in 1983. 4. EXTINCTIONS THREATEN THE BALANCE OF NATURE. In his 1979 book, The Sinking Ark, biologist Norman Myers estimated that an average of more than 100 human-caused extinctions occur each day, and that one million species would be lost by century's end. Yet there's little evidence of anywhere near that number of extinctions. For example, only seven species on the endangered species list have become extinct since the list was created in 1973. Biodiversity is an important value, according to many scientists. Nevertheless, the supposed mass extinction rates bandied about are achieved by multiplying unknowns by improbables to get imponderables. Many estimates, for instance, rely a great deal on a "species-area equation, which predicts that twice as many species will be found on 100 square miles as on ten square miles. The problem is that species are not distributed randomly, so which parts of a forest are destroyed may be as important as how much. One of the main causes of extinctions is deforestation. According to the Consultative Group on International Agricultural Research, what drives most tropical deforestation is not commercial logging, but "poor farmers who have no other option for feeding their families than slashing and burning a patch of forest." In countries that practice modern high-yield agriculture, forests are in no danger. In 1920, U. S. forests covered 732 million acres. Today they cover 737 million. Forests in Europe expanded from 361 million to 482 million acres between 1950 and 1990. In the early 1970s atmospheric scientists theorized that refrigerants called clorofluorocarbons (CFCs) - the best-known version is Freon - were percolating into the stratosphere, where they destroyed ozone that blocks damaging ultraviolet light from the sun. Indeed, it has since been confirmed that CFCs are largely responsible for the ozone hole that temporarily opens up over Antarctica every year. In 1978 the United States banned CFC's for use as propellants in aerosol sprays such as deodorants and perfumes. International treaties restricting the manufacture of CFCs and other ozone-depleting chemicals have also been adopted, and some scientists now expect levels of these damaging gases to peak at the end of this century and then begin to reverse. Although skin-cancer rates are up, the increase, according to most scientists, is attributable to life- style changes, not a thinner ozone layer. People today spend more time outside, at the beach and wearing skimpier clothing. There is more hype on this environmental issue than any other. In the late 1970's computer models predicted that because of the heat-trapping buildup of carbon dioxide in the atmosphere, the earth would warm up by several degrees over the next century. A lot of bad weather gets linked to global warming in the media, which regularly predict that more and fiercer hurricanes, longer droughts and more severe rainstorms will result. What has actually been going on? One computer model says the earth's temperature should have already increased by an easily detectable 0.3 to 0.4 degrees Celsius since 1979. Some satellite data, however, show that the earth's temperature as actually cooled slightly over the last 18 years. And despite seasonal variations, the frequency of intense Atlantic hurricanes and their maximum wind speed have not increased over the past half-century. If climate models turn out to be correct, it may be prudent to limit carbon-dioxide emissions in the future. But many experts feel there is no need to rush into drastic action. "We have a decade or so to collect data and refine our models before we might have to act," says Jerry North, professor of meteorology at Texas A&M. There is also time for scientists to develop less carbon-intensive energy technologies, which we can switch to later at a lower cost. "Even though it will disappoint many of you, the evidence is that you have a very bright future." This is how I finished my presentation at American University, eliciting a few chuckles from the audience. On a more serious note, I asked the students to consider a radical proposition: Economic growth and technological progress are not enemies of the environment but are perhaps its best friends, since they allow us to reduce humanity's foot- print on the natural world. High-tech agriculture boosts farm productivity, which means a cheaper food supply and more land spared for nature. Better sewage treatment means that our rivers and streams can run freer of pollutants. Catalytic converters on cars and better filters on power-plant smokestacks have greatly reduced smog, smoke and soot in the air. But only rich societies can afford to pay for these. In the end, the best environmental program of all is the promotion of prosperity.
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