Global deforestation: A statistical thicket


It’s all about forests: The United Nations declared 2011 “International Year of Forests”; the U.S. theme for World Environment Day on June 5 was, “Forests: Nature at Your Service.” This is an ideal opportunity to stop those barking up the wrong tree and debunk a long-running legend: the deforestation of the earth.

The lead-off sentence of the U.N. Food and Agriculture Organization’s (FAO) first survey of world forests in 1948, encapsulated the purpose, “The whole world is suffering from shortages of forest products.”

So deforestation was a concern even before mid-century. But environmental activism has since given the issue more appendages than a mother pig. This diffusion of purpose led to a conclusion in a 2000 FAO document that, “National and local forestry planning is seldom dominated by wood production and utilization,” a clean reversal since 1948.

Earth prophets have been relentless in predicting calamity. A 1979 New York Times article said, “The world’s forests are disappearing at an alarming rate, a loss that poses potentially dire economic and environmental problems for most of humanity …” The “alarming rate” description was epidemic in the 1980s and 1990s.

The alarm was partly about the demise of species; a 1985 report predicted “10 to 20 percent of the earth’s animal species” would disappear by 2000. It was also about loss of potential drugs for known and unknown ailments, unstable water supplies, increased global warming, increased soil erosion, desertification, even poverty.

Fortunately, as with so many environmental doomsday predictions, the reality is infinitely brighter. In its 1948 report, FAO estimated that the world had 4 billion hectares (a hectare is 2.47 acres) of forest. In 2010 the estimate was 4.03 billion hectares.

How did the “alarming” deforestation of four decades disappear? The answer is that FAO’s own estimates have been contradictory almost from the beginning. Two estimates given for 1963 differ by over 300 million hectares. But radical reassessment really began for the year 1990, after FAO tallied 3.4 billion hectares of forest and a loss of nearly a half-billion hectares since 1960.

FAO has repeatedly cautioned about the difficulty of estimating world forests and repeated revisions of the 1990 survey illustrate. Five FAO publications give different estimates, and the most recent (2010) listed 4.17 billion hectares of forest for 1990, the second highest estimate since 1948. The re-estimates wiped out the deforestation of 42 years.

Nevertheless, FAO continues to estimate large areas of deforestation. Its 2010 report claims: “The rate of deforestation shows signs of decreasing, but is still alarmingly high.” Eighty-three million hectares were reportedly lost in the 1990s and 52 million hectares since then.

The “alarming” loss of forest feared for so long appears to be 633 million hectares, yet hasn’t reduced the amount of forest since the 1960s. The change in forested areas reported since 1948 is not statistically significant. It is a maze of numbers, definitions and revisions that boggle the mind.

Definitions for some surveys have required that forests have 10 percent tree cover, but for others (even in the same year), 20 percent cover. Forest area in Australia almost quadrupled from 1990 to 2000 because the definition of forest was changed from 20 percent cover to 10 percent cover.

Forest clearing has occurred throughout history. Land for food has always had precedence over forests. But there are encouraging trends. Modernization and economic progress holds hope for future forests. Countries that are replenishing their forests today are those that can afford to; because they can grow more food on less land.

A recent analysis in the Proceedings of the National Academy of Sciences ties forest regeneration to economic progress. It noted the transition from net deforestation to reforestation that has occurred over the last 200 years in Europe and in America. France’s forest, for example, reached a low point of less than 15 percent of the land area in about 1830, and has since rebounded by one-third, while its population nearly doubled.

Among 50 nations currently with large forest areas, the analysis showed that every nation with a per capita gross domestic product of over $4,600 had a positive rate of forest growth.

So the good news about world forests is that, if they are declining, it is not much, and in some areas they are increasing. Europe (including the former Soviet Union) has 15 million more hectares of forest than in 1990 and China’s has grown by one-third.

Alarmed “global deforesters” can relax after 30 years, that is, if they can see the trend through the statistical thicket.

[University of Georgia Professor Emeritus R. Harold Brown is an Adjunct Scholar with the Georgia Public Policy Foundation and author of “The Greening of Georgia: The Improvement of the Environment in the Twentieth Century.” The Foundation is an independent think tank that proposes practical, market-oriented approaches to public policy to improve the lives of Georgians.]