On Bjorn Lomborg's use of statistics
Extraordinary claims demand an extraordinary level of documentation and supporting analysis, and warrant the healthy skepticism of those who would review or pronounce judgment on them. Bjorn Lomborg’s new book, The Skeptical Environmentalist, is missing the documentation and analysis, and the outpouring of media coverage the book has generated is missing the skepticism.
Lomborg’s extraordinary claims are that environmental quality is improving around the world, and that the environmental community is not admitting to those improvements for its own cynical reasons. Among Lomborg’s assertions that have captured media attention: Forests are not disappearing; the rate of species extinction has been wildly exaggerated; and global warming is not worth addressing and indeed will be a benefit for many.
Lomborg is entitled to his view that, as one chapter title reads, “Things are getting better.” However, his call for a more rational and scientific debate on environmental issues would be more persuasive if he cited authoritative scientific sources, quoted or paraphrased accurately, and used quantitative examples correctly — as a reader confronting a book with more than 3,000 footnotes might expect. Unfortunately, Lomborg commits just the sins for which he attacks environmentalists: exaggeration, sweeping generalizations, the presentation of false choices, selective use of data and quotations and, frequently, outright errors of fact.
For example, Lomborg asserts that “marine productivity has almost doubled since 1970.” While the tons of fish taken from the sea have indeed doubled, many marine fish stocks are now badly depleted as a result, and harvests of cod, swordfish, halibut, and many other commercially important species have crashed. There are literally hundreds of such misleading statements in the book.
Another example concerns climate, about which Lomborg’s book makes two fundamental assertions: that potential changes in the climate system are not large and that mitigation actions would be extravagantly expensive. Lomborg challenges the accuracy of models on which climate scenarios are based, asserting that global warming will not cause more flooding because the richer world of the future will protect itself.
Photo: Amanda Bicknel, FEMA.
He selectively cites economic studies to conclude, “It is far more expensive to cut CO2 [carbon dioxide] emissions radically than to pay the costs of adaptations to the increased temperatures.” Lomborg relies largely on one controversial economic model, and helps his case by representing the IPCC’s calculation of the 30-year cost of stabilizing greenhouse gas concentrations as a single year’s cost. While there can be no certainty in matters of future costs dependent on human decision-making, we can only note that multiple studies, including an exhaustive 1992 analysis by the U.S. National Academy of Sciences, have come to very different conclusions from Lomborg’s.
The consensus view of thousands of reputable scientists around the world is that human activities have clearly changed the composition of the atmosphere, have already resulted in detectable change in climate and biological resources, and are likely to result in much more rapid changes in climate than have been seen in the last 100,000 years. Lomborg dismisses this entire body of research, but it is far from clear why we should accept his own work as more reliable.
Beyond highly questionable assertions about specific environmental issues, Lomborg paints a caricature of the environmental agenda based on sometimes mistaken views widely held 30 years ago — his “Litany” — but to which no serious environmental institution subscribes today. Unlike Lomborg, leading environmental groups are well aware of current biological and climate science, and they pursue strategies based on providing information that allows people to make informed choices.
Perhaps the most troubling aspect of Lomborg’s book is what it leaves out. Readers will find no hint in The Skeptical Environmentalist of the extraordinary degree of cooperation between environmental organizations and many major global corporations — on voluntary corporate environmental reporting, on practical recycling or supply-chain strategies to reduce environmental footprints, on policy initiatives from climate to biodiversity conservation, on efforts to create markets for green power and sustainably harvested forest products.
Lomborg is apparently unaware of the rapid shift from command-and-control regulation to transparency and reporting requirements (for example, the U.S. Toxics Release Inventory has triggered far more massive, and voluntary, reductions of toxic emissions than any regulation); of the growing number of major corporations making voluntary commitments to reduce energy use, pollution, and toxic materials; of creative new policy initiatives to explore market-based strategies for solving environmental problems from air pollution to climate to habitat preservation.
It is these solution-oriented efforts that dominate the environmental agenda today and that account for the excitement and — yes — the guarded optimism that many environmental organizations feel, despite very serious challenges in the years ahead. But such efforts are not helped by a carelessly written and often inaccurate book focused on a false litany — one that essentially denies that real environmental and social challenges remain.
That denial is in itself one of the saddest aspects of Lomborg’s book, because it is only by building awareness and understanding of global environmental challenges that we can hope to solve them.