Fire and Ice

This book puts the global warming controversy in a very small nutshell

PHOTO: MIT Press

What We Know About Climate Change

By Kerry Emanuel, MIT Press, Cambridge, Mass., 2007; 85 pp.; US $14.95; ISBN-10: 0-262-05089-7

Reviewed by M. Granger Morgan

On Amazon.com, this book looks like any other: attractive cover, nice promotional blurbs. Imagine my surprise when my copy arrived: 12 by 18 ­centi­meters, 85 pages, wide margins, and only about 140 words to the page. Still, I am a great fan of Kerry Emanuel’s previous semitechnical book, the beautifully produced Divine Wind: The History and Science of Hurricanes (Oxford, 2005), so I sat down to read the seven brief chapters with interest. I was not disappointed.

Emanuel, a professor of atmospheric science at MIT, explains how and why the climate system has varied enormously over geologic time scales, and he does so in language so clear and concise that any college grad should be able to understand. With echoes of Robert Frost’s apocalyptic poem ”Fire and Ice,” he outlines why, despite these great swings, Earth has never careened into a permanent deep freeze or become overheated, as in the case of Venus, whose surface is hot enough to melt solder.

Next comes a clear explanation of planetary heat balance and the greenhouse effect, with a discussion of the central role of water vapor and clouds, a topic too often glossed over in descriptions for lay readers. Then, using the analogy of the paths traced over time by leaves falling into a turbulent brook, chapter 3 provides a masterly explanation of chaotic systems and why there is an inherent limit to how far ahead we can forecast the weather. This chapter is less successful in moving from the moment-by-moment characteri­zation of weather to the more stable average values that make up climate.

Chapter 4, which discusses climate models, includes the only plot in the book, comparing the output of a climate model based on ”natural” radiative forcing with one to which human emissions of greenhouse gases and aerosols have been added. Only the latter successfully repli­cates the past three decades of climate records. The author conveys this conclusion clearly in a diagram (despite the reference to ”colored curves” in what is, in fact, a black-and-white plot).

Having laid out the basics, in chapter 5 the author explains why even a modest increase in average global temperature may—by melting ice sheets, thus raising sea level—intensify droughts, floods, hurricanes, and other disasters. These changes would, of course, have a profound impact on the things people value.

The final two chapters describe in a brief and balanced way the nature and sources of the political controversy that has swirled around the issues of climate science. There is a good discussion of the self-correcting nature of the scientific method, and of how virtually all serious climate scientists now agree that the average atmospheric temperature is rising and that human activities are contributing to this trend. It also makes clear that sorting out some of the additional details will probably involve uncertainties that are irreducible on the time scale of the geophysical experiment we’re running with planet Earth. There is also an appropriate, if brief, discussion of the interest-group politics that have complicated ­public discourse, notably the role played by the handful of professional deniers who are forever being quoted by scientifically naive journalists seeking ”balance.”

Unfortunately, the final 15-page afterword by two other scholars was quite a letdown and detracted from the book’s overall effectiveness. Judith Layzer, an assistant professor of environmental policy at MIT, and William Moomaw, a professor of international environmental policy at Tufts University, in Medford, Mass., note that addressing the problem of climate change will require a fundamental restructuring of our energy system. They correctly suggest that if done properly this restructuring ”could be relatively painless.” However, as at the end of Al Gore’s documentary, An Inconvenient Truth (2006), when a somewhat random list of remedies scrolls past viewers, Layzer and Moomaw bounce through a potpourri of technologies and policies. This treatment fails to paint a compelling picture of what the United States or the rest of the world should do.

The book would have benefited from a one-page list of suggested further readings and Web addresses for those who do not know their way around this subject and would like to read more.

About the Author

M. GRANGER MORGAN, an IEEE Fellow, is head of the department of engineering and public policy at Carnegie Mellon University, in Pittsburgh.

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