Greenhouse Science


The Heated Debate: Greenhouse Predictions Versus Climate Reality, by Robert C. Balling Jr., San Francisco: Pacific Research Institute, 181 pages, $21.95

Carbon Dioxide and Global Change: Earth in Transition, by Sherwood B. Idso, Tempe, Ariz.: IBR Press, 292 pages, $19.95

Scientific Perspectives on the Greenhouse Problem, by Robert Jastrow, William Nierenberg, and Frederick Seitz, Ottawa, Ill.: The Marshall Press, 254 pages, $22.50

Global warming is often heralded as the gravest crisis facing the world. A recent trip to Borders, the largest book store in Indianapolis, failed to turn up a single statement in any book that global warming may not mean apocalypse. The store did have several books devoted exclusively or largely to global warming, and all contained rather extreme statements of disaster.

Paul and Anne Ehrlich say in Healing the Planet: "Global warming is probably the greatest single environmental threat to the security of the United States and all other nations." Michael Oppenheimer and Robert Boyle write in Dead Heat: "Humanity is hurtling toward a precipice. Left unchecked, the emissions of various gases, particularly carbon dioxide…are likely to alter the Earth's climate so rapidly and so thoroughly as to destroy much of the natural world and turn the world that we call civilization upside down."

Likewise Sen. Albert Gore (D–Tenn.), in his newly released Earth in the Balance, describes global warming as "the most serious threat that we have ever faced." In his dust-jacket endorsement of Gore's book, Bill Moyers claims, "In this eloquent and unusual memoir of discovery Al Gore faces honestly the unremitting evidence of science."

But it is precisely science that is frequently overlooked in public environmental debates. And nowhere is this trend more pronounced than in the controversy over global warming.

Take, for example, a 1990 survey of 100 Alabama professionals (doctors, attorneys, and college professors). Ninety-five said that Alabama had warmed over the last two to four decades and that the warming was associated with the greenhouse effect. The state has actually cooled significantly Since 1935.

Little known to the general public, there is a raging scientific debate about virtually every aspect of the global-warming scenario. The three books under review attempt to bring that debate before the intelligent layman and to consider the scientific evidence. All three books are lucid and accessible. While complementary, these books differ in the questions they address and the answers they offer.

Robert C. Balling's The Heated Debate is the newest and hence the most up-to-date. Director of the Office of Climatology at Arizona State University, Balling shows how the climate seems to be evolving on the basis of the climate record. His book contains 53 charts and graphs and is filled with information; yet it is presented in an easy-to-read, straightforward way that judiciously offers both sides of every argument. When the data conflict, Balling acknowledges the uncertainty. But most of the data do paint a coherent picture of where we may be headed. Aaron Wildavsky's foreword is argumentative in a way that Balling's text never is.

Sherwood Idso's Carbon Dioxide and Global Change has been out for three years but has gotten little attention. This lack of response is unfortunate, because Idso's book deserves much better.

Of these three books, Idso's has the most-detailed discussion of global-warming theory. He describes simply and yet in detail the profound uncertainties regarding the historical climate record and the causal connection between carbon dioxide and temperature. His analysis of the shortcomings of climate models is also the most definitive. While occasional scientific jargon may impede a quick reading, Idso's book is so interesting and rich in detail that it is well worth the effort. In addition, about half of the book consists of footnotes to sources, so Idso's grasp of the literature cannot be questioned, and any interested person can find out more about the relevant issues.

Scientific Perspectives on the Greenhouse Problem, by Robert Jastrow, William Nierenberg, and Frederick Seitz, is the weakest of the three books. Jastrow and his colleagues actually wrote only the first part of the book, and that part is the best. They argue that the facts don't support the theory of global warming and speculate that solar activity may explain temperature variations. The second and third parts of the book consist of articles by other authors regarding the greenhouse debate and tend to be dry and uninteresting.

The greenhouse-effect theory is that carbon dioxide and other chemicals released into the air trap heat from the sun, raising the earth's temperature and causing a variety of severe ecological problems. Inland droughts, more-intense tropical storms, the melting of the polar ice caps, and the slow inundation of low-lying areas are the main problems scientists foresee if the emission of greenhouse gases continues.

These predictions are almost entirely the result of complex climate models that try to simulate the earth's weather systems. Both Idso and Balling describe in detail the many reasons for being skeptical about the reliability of these models.

Above all, the models cannot assess accurately the effects of clouds. Balling shows that clouds may warm or cool the climate, and it is unknown which is more likely to happen in a world with increased greenhouse gases. Other factors that the models ignore or inadequately consider include the effects of oceans, sea ice, snow cover, sun activity, and pollutants that scientists acknowledge cool the atmosphere.

Because of changing ideas about these and other variables, model predictions have often been inconsistent and have tended to change over time. For example, the amount of sea-level rise predicted by the models has declined substantially. The 1980 estimate by two well-known greenhouse theorists that the greenhouse temperature increase would raise sea levels by 25 feet over the next 150 years has been abandoned. Both Balling and Jastrow and company state that, at most, a foot rise is now expected. Indeed, a report in the December 1991 edition of the scientific journal Geology (too recent to be mentioned in any of these books) stated that rising temperatures would most likely lower sea level by increasing the buildup of ice and snow.

Of the three books, Balling's is the best for testing the model predictions against the climate record. His research (cited in detail) tries to show the extent of consensus between the modelers and those scientists who focus on historical climatic data.

Despite the shortcomings in the models, their predictions fit some of the existing climate record. Cloud cover and precipitation have increased, as many modelers thought they would. But the area of prediction in which the models conflict most with the known climate record is the one most central to the greenhouse scare: temperature.

Balling admits that the record as we have it shows a global temperature increase over the last century, though one considerably less than the 0.5 degree Celsius commonly asserted. Since the models would have predicted a temperature increase of about one degree Celsius during that time based on the increases of greenhouse gases, they are off by a factor of more than two. Moreover, the models suggest that the greatest warming would be over the polar regions. But the Arctic has experienced significant cooling since 1940, contradicting the model predictions. Furthermore, the best temperature records are from the United States, and they show no warming and even a slight cooling from 1920 to 1987.

Although Balling seems willing to ascribe part of the asserted worldwide temperature increase to the greenhouse effect, Jastrow and his colleagues are not. They point out that most of that rise predated the principal increase in greenhouse emissions. When the emissions went up sizably starting about 1940, the temperature actually declined dramatically until about 1970. And the hyper-precise temperature measurements taken by satellites show no upward trend in the 1980s either. (In fact, as John Christy of NASA has noted, the satellite data reveal no statistically significant temperature trends from 1977 to 1991.)

Balling isn't as skeptical of global warming as Jastrow and his colleagues are. But he shows that the warming will primarily affect the minimum temperature level. In other words, winter nights at high latitudes won't be as cold as they might have been absent greenhouse gases. After his book was typeset, a major study published in December 1991 in Geophysical Research Letters confirmed the research that Balling cites. Thomas Karl and a team of scientists showed that across the Northern Hemisphere the main effect of warming has been to push up daily minimum temperatures rather than increasing daily high temperatures. This result also does not accord with the models, which do not differentiate between daytime and nighttime.

If the main consequence of the greenhouse effect is to raise minimum temperatures, the result could be beneficial. There would be less thermal stress on plants and animals, and plants would have longer growing seasons.

While Balling makes these points in a cursory way, Idso, who has conducted numerous studies in this area, elaborates upon the benefits that plants will reap from the increased concentration of atmospheric carbon dioxide. Plants will be considerably larger and more productive: Idso's research suggests that the harvestable yield from plants will increase by 30 percent if carbon dioxide doubles. Plants will use water and nutrients more efficiently and will be better able to handle environmental stress. They will be able to grow in desert areas where they cannot easily grow at present and grow more fully in other regions, thereby reducing topsoil erosion.

Despite the differences in their approaches, the authors of these three books have one thing in common: All have been criticized and ridiculed for adding an unpopular dimension to the global-warming debate. Scientific American and Science routinely publish articles about environmental dangers and give little or no attention to those who call them into question. Idso told me that the same articles he writes that are accepted for publication by more-sophisticated scientific journals are rejected by Science because of their point of view.

Last year, scientists at a Norwegian institute submitted a paper to Nature calling certain carbon-dioxide measurements into question. The paper was rejected because of its implications for the theory of global warming. The reviewer noted that "the Greenhouse Effect research carried out during the last 30 years cannot be wrong."

Thus, in a curious way, those who make alarming statements about the greenhouse effect are right, for there is indeed much at stake. But the question is not whether the earth is on the verge of environmental collapse brought on by global warming, which it is not. The question is whether politics will so invade science that scientific judgment will be lost and courses of action will be taken so hurriedly and unwisely that we will imperil the civilization the alarmists profess they wish to protect.

David A. Lips is a program officer at Liberty Fund Inc. in Indianapolis.