- American Physical Society Sites
- Meetings & Events
- Policy & Advocacy
- Careers In Physics
- About APS
- Become a Member
By Greg Craven (Penguin, New York, 2009) 264 pp. $14.95. ISBN 978-0-399-53501-7.
I asked to review this book because I was curious to see what a fellow high school physics and chemistry teacher had to offer on the subject of climate change, which has captured my interest and concern ever since I worked with NSTA in the summer of 1979 to develop a curriculum about it. I was not disappointed. I was greeted by eleven engagingly written chapters presenting no “graphs and footnotes to convince you which side is right” but rather “a set of thinking tools so you can reach your own conclusion.” (p. 4)
Craven’s approach follows from his philosophy that “the real question about dangerous global warming is not, Is it true? But, Is it worth doing anything about, just in case it’s true?” (p. 11) To him the issue of climate change is one of security for the future threatened by climate destabilization. Thus, he chooses to think of it in terms of risk management, and he spends his first chapter (numbered zero and titled “Should I bother to read this book?”) making sure that his readers are “on board” with him. The key, he points out in that introductory chapter, is a decision grid, with two columns—A (“significant action now”) and B (“little to no action now”)—and two rows—whether global warming is false or true. We aren’t sure about the rows, he says, though we can estimate their probabilities, but we do have control of the columns.
Before reading Chapter 1, Craven’s readers are asked to write what they would have to see for their opinion about global warming to be changed. (If you can’t answer this, he says, your mind can’t be changed so there’s no point in reading the book.) This and the next four chapters are devoted to developing a “tool kit” (spelled out on pages 104-105) to facilitate completing the decision grid in the last half of the book. Among the tools are the realization that there cannot be a complete consensus about something scientific, though it can be well accepted or established, and strategies for avoiding “confirmation bias” (looking for supportive but not opposing evidence—it “tricks you into being wrong with confidence” (p. 65)). To guard against confirmation bias in filling out our decision grid, we also need to develop a “credibility spectrum”—a chart for each side of the issue, with spaces along a line from “most credible” to “least credible” for information from various types of sources.
In Chapter 6 Craven presents the information he has gathered from the “warmers,” his name for those who believe the climate is warming and in taking action to oppose it. In Chapter 7 he does the same for the “skeptics.” But because he feels that “the shrill urgency of the warmers . . . in Chapter 6 defies common sense (p. 149),” Craven also devotes Chapter 8 to exploring their arguments. Here he points out that “It’s not the temperature rise that gets you but what it causes.” (p. 157) More than climate change, warmers are concerned about climate destabilization, characterized by rising sea levels and attendant increased storm surges, increased range of pests and disease-spreading insects and agricultural losses and illness, changing rainfall patterns, more frequent and extreme weather events, collapse of the “conveyor belt” that keeps Northern Europe warm, and changing relationships among species.
Craven likens the global atmosphere to financial markets: both, he says, are complex dynamical systems, with many connected elements and feedback loops, which can lead to erratic behavior—i.e., destabilization. Financial markets represent experiments with our economic system, the atmosphere an experiment with our planet. Among the factors affecting feedback loops are phytoplankton, trees, the Earth’s albedo, methane hydrates, the aforementioned “conveyor,” ice sheets, and peat. Climate destabilization would be characterized by a “tipping point,” marking a change beyond which there could be no return. Craven notes the difficulty identifying tipping points due to 1) omission of positive feedback loops in climate models (because we don’t understand them sufficiently) and 2) the abruptness of climate change in the past, evidence for which has been found only since the 1990s and which is the focus of the National Research Council report, Abrupt Climate Change, issued in 2002. Before that, a 20oF temperature difference over a period of 10,000 years was believed to have occurred at a roughly constant rate over the entire time, but it is now known to have occurred in a 100-year period during those 10,000 years.
Craven uses the imagery of Abrupt Climate Change, which depicts the transition of a mechanical system from one equilibrium state to another, to represent two climate states—glacial and interglacial—between which the Earth has flipped over the past three million years, with changes between these climate states occurring over short periods of 100 years. The transition between equilibrium states is expressed as two energy wells separated by a hill. The rapidity of climate change in the past causes Craven to wonder how much human action has gone to push our present climate system up a “hill” on the other side of which is another climate system from which we can’t return and whether stabilizing our climate at an elevated average global temperature by controlling carbon emissions at present values could put us at greater risk. It also leaves him with the feeling that the IPCC model predictions are rendered even more conservative, because they don’t predict such rapid climate change in the past.
When, in Chapter 9, Craven assembles his credibility spectra for taking and not taking action on climate change, he finds that the spectrum for not taking action is sparse for the most credible types of sources—statements from professional societies and statements from organizations that contradict their normal bias. This, coupled with the strong statements for taking action from three different communities—science, business, and national security—leads him to consider that global warming is far more probably true than false, and he chooses column A on his decision grid. Chapter 10 invites readers to complete their own decision grids.
James Hansen, characterized as an accepted global warming bellweather, is cited as saying that avoiding a climate tipping point requires ending coal combustion by 2030. According to Craven, “that means we need to be on a very different track by 2015” (p. 216), unless we can bring about cultural change at the rate we geared up for World War II. Craven concedes that, unlike Hitler and Hirohito, carbon dioxide emissions are an enemy without a face to motivate us, but he feels that today’s milieu of digital communications could allow a “viral spread of the meme that we should change the question in the global warming debate from, Is it true? to, Why risk it?” (p. 222) Thus he passes the torch to achieve this to his readers. But it is now 2015, and the carbon dioxide concentration in the atmosphere is up to 400 parts per million from the 388 when Craven wrote his book. We have burned less coal, but only because we have replaced it with “fracked” natural gas, and we have increased production of another fossil fuel, oil, from tar sands and oil shale. Although more than a million saw Craven’s YouTube video (“The Most Terrifying Video You’ll Ever See”) in less than a year, are we any more culturally mobilized to oppose climate change?
John L. Roeder
The Calhoun School
New York, NY