Hot air

Global warming is not as bad as it's made out to be, argues Bjørn Lomborg. But he cherry-picks evidence to manufacture a scientific and economic consensus that doesn't exist.

By Eban Goodstein

Read more: Books, Reviews, Book reviews, Global Warming, Climate Change

Aug. 29, 2007 | The place is somewhere in Turkey, 5,200 years ago. Noah has just gotten word about an upcoming episode of abrupt climate change, and he and his family are hard at work building an ark. The plan is to take on board mating pairs of every living thing of all flesh, every creeping thing of the ground, in order, as God put it, to keep them alive.

Up walks a man who introduces himself as an adjunct professor at the Copenhagen Business School. He says, "Noah, you have to stop. We've run the numbers and they don't add up. I agree that there may be a few days of rain, but if you really want to help future generations, don't build the ark. Grow the economy!"

In "Cool It: The Skeptical Environmentalist's Guide to Global Warming," that Copenhagen Business School professor, Bjørn Lomborg, is at it again, preaching the gospel of benefit-cost analysis. His message: Don't take any serious action to stop global warming pollution because doing so will slow down economic growth that poor people need, and anyway, it's really not going to rain that hard.

Lomborg's first effort, "The Skeptical Environmentalist," made a splash in 2001 with a mixture of polemics targeted at scare-mongering environmentalists. With its voluminous footnotes, Lomborg appeared to have done his homework. But on closer examination, some of the facts were not so well supported and Lomborg was widely accused of cherry-picking to support his arguments. Eminent Harvard biologist E.O. Wilson called the work a "sordid mess."

In "Cool It," Lomborg has three messages. First, the planet will warm up no more than 4.7 degrees Fahrenheit this century, and on balance, this will be bad, but not too bad. Second, all benefit-cost models show that serious limits on global warming emissions are too costly, and therefore we should pollute with virtual impunity. And -- surprisingly -- we should invest a decent amount ($25 billion per year) in clean energy technologies now so that, starting in a few decades, we will have tools to slow down global warming just a little bit through 2100.

How much is a 4.7 degree warming? During the last ice age, a period of time during which much of North America was covered with hundreds of meters of ice, the world was only 9 degrees colder than it is today. Lomborg's world in 2100 -- what he calls the "standard" estimate from the U.N.'s Intergovernmental Panel on Climate Change -- is already halfway to a shift in temperatures of ice age magnitude, only hotter not colder, within our children's lifetimes.

To make his case that this "moderate" warming won't do too much harm, Lomborg puts much weight on the argument that as the world heats up, reductions in deaths from cold might significantly outweigh increased heat deaths. But as Frank Ackerman at Tufts has shown, such a conclusion holds only if one incorrectly assumes that people do not adapt to what Lomborg insists will be very gradual temperature changes. Here as elsewhere, Lomborg presents scientific and economic debates as much more settled than they are.

But this really is not the point. The glaring error in "Cool It," and the one that disqualifies the book from making a serious contribution, is that Lomborg ignores the main concern driving the debate. Incredibly, he never mentions even the possibility that the world might heat up more than 4.7 degrees. Although he claims IPCC science as gospel, in fact the scientific body gives no single "standard" estimate as its official forecast for this century's warming. Instead, the IPCC provides a range of up to 10.5 degrees -- more than double the number on which Lomborg bases his entire argument.

The global warming "alarmism" that Lomborg finds so distasteful is motivated by a serious, science-driven concern that hidden within our global climate system are powerful positive feedback loops. So that as we inch up from 3 to 4 and then 4 to 5 degrees of warming, we may very well cross some temperature threshold that would trigger a couple of degrees of further warming, causing a catastrophic upward spiral in global temperatures.

For example, if the Amazon heats up and dries out too much, much of it could burn down, flipping to savannah, and releasing tens of billions of tons of CO2 into the atmosphere. Similarly, as the permafrost in the Arctic melts, a huge pulse of methane may be released. The science is clear that, interacting, these and other biophysical and socioeconomic factors could drive planetary temperatures far beyond the range that Lomborg addresses. By ignoring the vast uncertainty underlying these forecasts, and every alternative outcome except his preferred "moderate" warming scenario, "Cool It" reduces to an uninteresting discussion of why folks alive today should choose 4.7 degrees of warming rather than 4.4 as the optimal outcome for our grandkids.

On sea level rise, Lomborg assures us, with serene confidence, that it will stop at a serious but manageable one foot by the end of the century. The book omits any reference to Dr. James Hansen, head of NASA Goddard's Space Research Institute at Columbia University. A growing body of research led Hansen to declare earlier this year that Lomborg's favored business-as-usual scenario "would guarantee future disintegration of West Antarctica and parts of Greenland." This in turn would guarantee a long-run, irreversible sea level rise of 20 feet or more, with the potential for a several-foot increase this century.

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