Statistics in the News: Chapter 19 Time Series and Forecasting

From an Unlikely Quarter, Eco-Optimism

The news from environmental organizations is almost always bleak. The climate is out of whack. Insidious chemicals taint food and drink. Tropical forests are disappearing. Species are perishing en masse. Industrial poisons pollute air, land, and water. Ecosystems are being stressed to the breaking point by the greedy, wasteful consumption of the Western lifestyle. The list goes on. Typical examples abound at the site of the Worldwatch Institute; just visit http://www.worldwatch.org.

So it is a surprise to meet someone who calls himself an environmentalist but who asserts that things are getting better, that the rate of human population growth is past its peak, that agriculture is sustainable and pollution is ebbing, that forests are not disappearing, that there is no wholesale destruction of plant and animal species, and that even global warming is not as serious as commonly portrayed.

The author of this happy thesis is not a steely-eyed economist at a conservative Washington think tank but a vegetarian, backpack-toting Danish professor of statistics who was even a member of Greenpeace not so long ago. Professor Bjorn Lomborg from the University of Aarhus arrived at this position by accident, after reading about the famous controversy (presented in the Preview of Chapter 19) between Paul H. Ehrlich, the Stanford University ecologist and author of The Population Bomb, and Julian L. Simon, the University of Maryland economist and author of The Ultimate Resource. Prof. Lomborg felt sure that Simon's optimistic contentions were "simple American right-wing propaganda." So he initiated nightly study sessions with his statistics students to debunk Simon, drawing data from reports of the World Bank, the Food and Agriculture Organization, the United States Environmental Protection Agency, the International Panel on Climate Change, and other official sources. Yet Lomborg found that most of Simon's assertions were correct!

At the same time, Lomborg's work confirms the Chapter 19 warning: "Whenever someone says, 'given present trends…variable X will do this or that,' you better watch out." Lomborg found that routine assertions made by environmental organizations, such as the Worldwatch Institute, the World Wildlife Fund, and Greenpeace, were exaggerated or outright myths. In his book, he refers to the persistently gloomy fare from these sources as the Litany. He chides journalists for uncritically spreading the Litany and the public for an unfounded readiness to believe the worst. "The Litany has pervaded the debate so deeply and so long," writes Lomborg, "that blatantly false claims can be made again and again, without any references, and yet still be believed." To understand the world as it is, he says, it is necessary to look at long-term global trends that tell more of the whole story than short-term [anecdotes] and are less easy to manipulate.

His examples include:

1) In its 1998 State of the World report, the Worldwatch Institute said: "The world's forest estate has declined significantly in both area and quality in recent decades." But the longest data series of annual figures (available from the United Nations' Food and Agriculture Organization) shows that global forest cover between 1950 and 1994 has in fact increased.

2) The same Worldwatch report claimed that due to soaring demand for paper, "Canada is losing some 200,000 hectares of forest a year." Yet the cited reference shows Canada growing 174,600 more hectares of forest a year.

3) In its 2000 report, the Worldwatch Institute cited the dangers it had foreseen even in 1984: "Record rates of population growth, soaring oil prices, debilitating levels of international debt, and extensive damage to forests from the new phenomenon of acid rain." Yet Lomborg shows that the rate of world population growth has been dropping sharply since 1964, that the price of oil--adjusted for inflation--has halved since the early 1980s, that the level of international debt has decreased slightly between 1984 and 1999, and that sulfur emissions that generate acid rain have been cut substantially since 1984 (and have done little if any damage to forests, though some to lakes).

4) According to Ehrlich in 1961, "in the course of the 1970s, the world will experience starvation of tragic proportions--hundreds of millions of people will starve to death." Yet Lomborg finds world population doubled since 1961, while calorie intake has increased by 24 percent as a whole and by 38 percent in developing countries.

5) Lomborg also takes issue with global warming predictions. Four reasons are usually cited as to how waste gases could warm the world's climate. These include the multiplier effect of carbon dioxide, the role of clouds, the effect of aerosols, and the sunspot cycle. According to the multiplier effect, as carbon dioxide heats the atmosphere a little, the air can hold more water, and that heats the atmosphere a lot more. Yet Lomborg's satellite and weather balloon data weaken the case for such a multiplier effect. And he argues that the climate model employed by the International Panel on Climate Change exaggerates the effects of greenhouse gases.

6) Lomborg portrays several other elements of the Litany as little more than myths. These include the claim that the world is about to lose half or more of its species. (The often quoted figure that 40,000 species are lost every year comes from a 1979 article by Norman Myers, an Oxford University ecologist who, without any evidence, simply speculated that 1 million species might be lost between 1975 and 2000, which comes to 40,000 a year.) Yet the International Union for the Conservation of Nature, which maintains the Red Book of endangered species, in fact concluded in 1992 that extinction figures for mammals and birds were "very small" and that the total extinction rate, out of 30 million species, was probably 2,300 a year. A far cry from what Myers, even in 1999, called "a human-caused biotic holocaust."

Sources: Adapted from John Tierney, "Betting the Planet," The New York Times Magazine, December 2, 1990, pp. 52-81, and Nicholas Wade, "From an Unlikely Quarter, Eco-Optimism," The New York Times, August 7, 2001, pp. D1 and 2.

Additional Readings:

Lomborg, Bjorn. The Skeptical Environmentalist (Cambridge University Press, 2002).
A substantial work of statistical analysis, with almost 3,000 footnotes, that criticizes false statements routinely made by environmental organizations, such as the Worldwatch Institute, the World Wildlife Fund, and Greenpeace, that are typically based on questionable "trends."