To the Editor:

In “Greenhouse Anxiety” [July], Jeffrey Salmon argues that many scientists have wildly exaggerated the threat posed by global warming, thereby stirring disproportionate concern among policy-makers and providing fodder for environmentalists who are supposedly hellbent on slashing fossil-fuel use at any cost. But the fragmentary picture of global-warming science he presents is extremely misleading. His dismissive attitude on the wisdom of actions to mitigate greenhouse-gas emissions contrasts sharply with independent multidisciplinary assessments.

Mr. Salmon cites cautionary statements from Frank Press, president of the National Academy of Sciences, and Robert White, president of the National Academy of Engineering. But he fails to note that both signed a letter to the then-President-elect George Bush in 1988 which opened with the following sentence: “The problem of global environmental change is now widely recognized as one of growing urgency that will require responses by your administration.” The letter called for efforts to reduce reliance on fossil fuels. Mr. Salmon also fails to mention that the National Academy of Sciences elaborated on these concerns in its 1991 report, Policy Implications of Greenhouse Warming. The most comprehensive multidisciplinary assessment of global warming to date, this report was produced by a panel chaired by Daniel J. Evans, former Republican governor of Washington, and included, among others, Robert A. Frosch, vice president of General Motors Research Laboratories; William D. Nordhaus, professor of economics at Yale; and Sir Crispin Tickell, former UN ambassador from the United Kingdom. These people are not screaming radicals of the environmental movement; nor are they ivory-tower scientists without a notion of the practical implications of their proposals.

Among the report’s conclusions were that “despite the great uncertainties, greenhouse warming is a potential threat sufficient to justify action now.” The panel also concluded that “substantial mitigation [of emissions] can be accomplished at a modest cost. In other words, insurance [against undesirable levels of warming] is cheap.”

Mr. Salmon’s discussion of technical points is also selective to the point of inaccuracy. Global-warming concerns are soundly based on a variety of findings; comparison of the warming of the past 100 years with the predictions of global-circulation models is only one type of evidence, and not a very useful one, as I will explain.

Among the outcomes that the greenhouse-gas theory reproduces with considerable success are the amount of cooling which occurred between the end of the dinosaur age (about 65 million years ago) and today, and the amount of warming which occurred as the last ice age ended (comparable to the warming expected over the coming century). Both shifts were accompanied by large natural swings in the amount of carbon dioxide (CO₂) in the atmosphere and both were characterized by a degree of global-temperature change reproduced by the theory. From an ecological viewpoint, both climate changes also remade the face of the earth. Unmitigated greenhouse warming, which is expected to increase global temperature by 3°-8°F over the next century, would do the same.

Mr. Salmon’s discussion of the 100-year trend is itself akin to criticizing Newton’s theory of gravity because a feather floats downward rather than plummeting; there are many factors at work in both cases which make the particular example a complex and insufficient one for testing the theory.

In the case of the feather, it is the resistance of air which complicates matters. In the case of the 100-year temperature change and its temporal and geographic pattern, it is small solar fluctuations, random climate variations, a lag in warming caused by the thermal inertia of the oceans, and the reflective power of particles released by coal-burning which obscure the underlying greenhouse warming.

In the case of gravity, replacing the feather with a stone reduces the complication of air resistance to negligible levels. In the case of global warming, the greenhouse effect will come to dominate the complicating factors in relative importance as the level of greenhouse gases swells in the future. In any case, recent attempts to account for these complicating factors bring the greenhouse-model predictions into reasonable agreement with the observed global trend.

Finally, scientific results published this year have added a new cause for concern. Analyses of samples of ancient air trapped in ice cores taken from the Greenland ice cap indicate that the past 10,000 years, the period when civilization developed, have been a climatic oddity. Climate has been anomalously stable, with global temperature variations of only about 2°F up or down. In earlier times, climate in the North Atlantic area in particular oscillated wildly. Pumping up the greenhouse gases, which are known to be an important factor in controlling climate, could terminate this stability. If “insurance is cheap” in guarding against such an outcome, why not start buying some now by reducing emissions?

Michael Oppenheimer
Environmental Defense Fund
New York City

_____________

To the Editor:

Jeffrey Salmon claims that measures to mitigate human-induced climate change are unnecessary. This is a fallacious argument. Mr. Salmon severely misrepresents the views of environmentally concerned people, the major points of the arguments, and the very nature of the debate itself. He belittles the importance of the climate system, upon which all life is dependent, by grouping it with all other environmental problems, and he ignores a wealth of evidence to indicate that mitigative measures are called for.

Mr. Salmon clouds the issue by labeling as “advocates” those with viewpoints opposed to his, portraying them as a homogeneous group, and then attributing the most extreme language to them. He lambastes “scientists who have lent their authority” to ideas that he describes in outrageous phrases like “uncontrollable temperature rise,” “catastrophic,” “apocalypse,” and “an earth on fire,” when the overwhelming majority of scientists would never use such terminology. He goes so far as to claim that scientists have “collaborated in gross distortions” only for the personal gain to be had from publicity. In fact, perhaps the worst thing a scientist could hope for is to get vast publicity for an idea that is later proved wrong (e.g., the cold-fusion fiasco).

Policy-making on environmental issues is difficult. It almost always involves working with incomplete information. Policy-makers, however, are compelled to provide convincing information and demonstrate detailed knowledge to justify policy. Mr. Salmon muddles the debate by failing to present complete information and to distinguish, when possible, between scientific and policy issues.

For example, the same basic information about Lyme disease is available to all. . . . Some parents may allow their children to play outdoors unrestrained; others may require their children to wear long pants and sleeves; still others may bar their children from playing outdoors altogether. Can any scientist predict the number of ticks that will appear in a particular backyard? No. Is it possible to find scientists who disagree about the magnitude of the potential risk? Probably. Does the fact of incomplete information and disagreement among scientists mean that there is no problem? No. Does it mean that scientists who voice concern are purposely misleading and scaring the public? Of course not. As with global environmental issues, the decision as to what action to take in the face of incomplete information is a policy debate, not a scientific one.

Mr. Salmon ignores much relevant information. He claims that “every [his emphasis] greenhouse forecast . . . is the result of computers attempting to model” the climate system, and bases much of his argument on attacking the reliability of the climate models. He refuses to acknowledge the extent to which the models have been validated. Additionally, he completely ignores geologic data unrelated to climate models that support the link between greenhouse gases and climate.

Ice cores drilled in Greenland and Antarctica provide clues about the earth’s environment for a period of more than 150,000 years. Carbon dioxide and methane concentrations parallel temperature fluctuations associated with the ice ages, with increased greenhouse gases corresponding to warmer climates. Currently, results are beginning to be published from the two newest ice cores drilled in Greenland. They reveal that past climate fluctuations occurred even more swiftly than was believed possible during interglacial (non-ice-age) periods (changes of up to 10°C in one to two decades). The implication is that rapid climate fluctuations could occur again, perhaps during our lifetime. Results published so far indicate that at least one greenhouse gas, methane, was involved.

On even longer time scales there is remarkable consistency between theoretical calculations and data. Evidence and theory indicate that glacial periods as ancient as 300 million years ago occurred during times of low CO₂. Warmer periods such as the Cretaceous (135-65 million years ago) correspond to higher CO₂. The only period for which conflicting data exist is the late Ordovician (about 440 million years ago). These periods during which the earth’s landscape was profoundly different from our own—milethick ice sheets covering much of North America, or large dinosaurs and lush vegetation even in polar regions—correspond to greenhouse-gas changes similar in magnitude to that predicted with continued fossil-fuel use. This is basic evidence, ignored by Mr. Salmon, of the power of trace gases to affect climate.

If greenhouse gases have been so closely tied to climate in the past, there is every reason to believe that the same will be true in the future. If the opposite were true, and past climates bore no relation to greenhouse gases, the theory would be largely refuted. Geological evidence reflects actual conditions, and therefore includes all climate-change mechanisms such as the response of clouds. Our inadequate knowledge of many processes does not affect this result: if the data indicate strong correlations between greenhouse gases and climate fluctuations, then the correlation is true regardless of whether cloudiness increased or decreased.

Regarding global temperature changes over the last century, Mr. Salmon contends that the cooling which occurred from the mid-1940’s to the 1960’s contradicts the enhanced greenhouse theory. That is not true. All scientists who have attempted to simulate these changes, including James Hansen and Stephen Schneider, who are specifically criticized by Mr. Salmon, clearly acknowledge that such short-term fluctuations are attributable to other major climate forces such as solar cycles and volcanic dust. In other words, we know that many factors affect the climate; a perfect correlation with CO₂ is not expected. . . .

A balanced presentation of the issues would have better served COMMENTARY’s readership. . . .

Allan Frei
Department of Geography
Rutgers University
New Brunswick, New Jersey

Stuart Gaffin
Environmental Defense Fund
New York City

_____________

To the Editor:

Scientist-bashing can be highly entertaining fiction. As in Michael Crichton’s Jurassic Park, Jeffrey Salmon, in “Greenhouse Anxiety,” has peopled his world with scientists who are willing to play fast and loose with facts in order to cater to their own twisted egos.

Mr. Salmon accuses scientists of panicking the public on global warming to further their own goals. . . . [But] the basic premise of a global-climate effect from human activities is supported by a large body of literature extending over decades.

He goes out of his way to impugn the scientific credibility of those who are concerned about global warming. Yet he fails the basic test of journalistic credibility by neglecting to present many of those aspects of the global-warming scenario that give scientists and physicians the greatest concern. He tells us all about natural cycles in the earth’s temperature, but leaves out the salient fact that the mid-range projection of the rate of warming of the biosphere appears to be unprecedented in the human history of this planet. Nor, obviously, has any such change in climate occurred when the earth has had as many human inhabitants or the current burden of ecological insults.

Mr. Salmon also omits any mention of the slow reversibility of any effect. While some scientists may predict that greenhouse gases will have only a small effect on the earth’s climate, few, if any, will disagree with the statement that it would take a period of perhaps decades to reverse the effects on the earth’s biosphere of any warming that might occur. Thus, Mr. Salmon is misleading when he tells us that waiting five years will only increase the temperature at most one-tenth of a degree, but tells us nothing about how much time it will take to reverse the problems caused by this rise.

As a scientist, I am skeptical about theories that have yet to be validated by experience or of theories that are developed to explain events after the fact. In the sweltering heat of. . . yet another record hot summer, I suggest to Mr. Salmon that he ought to take more seriously the longstanding scientific prediction of a global-warming effect due to human activities.

Bernard D. Goldstein, M.D.
Director, Environmental and Occupational Health and Sciences Institute
Piscataway, New Jersey

_____________

To the Editor:

Jeffrey Salmon’s “Greenhouse Anxiety” is a strong and effective article. But perhaps because of its brevity, Mr. Salmon does not discuss a number of related issues.

• What ever happened to nuclear winter? Not very long ago we were being told that because of nuclear testing the world was already doomed to an extended period of reduced sunlight, falling temperatures, and a generally mean existence. I do not recall reading any apology from any environmentalist saying, “We were simply in error.” For that matter, why should we be worrying about the effects of fossil fuels when we were assured not long ago that by now we would have run out of fossil fuels, or certainly be on the verge of running out?
• Paul Ehrlich remains a chief guru of the environmental movement. In his book, The Population Bomb, written in 1968, he maintained that despite any crash programs then adopted, millions and millions of people around the world would be starving by the 1970’s. There was some starvation, but that was due to oppression, civil wars, ethnic conflicts, or infrastructure problems. Clearly, the world has the capacity to produce enough food for everyone on earth into the near future, even with population growth.
• Other issues could have been cited, including the errors in prediction of the movement’s patron saint, Rachel Carson.

The record is rather clear: of all the recent political forces and movements, the environmentalists have been the most consistently and totally incorrect. For better or worse, it appears that our planet will be with us, and in relatively good shape, for a long time.

Donald Feldstein
Teaneck, New Jersey

_____________

To the Editor:

Jeffrey Salmon . . . provides a clear and convincing overview of some of the most important distortions that have dominated public discussion of the greenhouse effect. While its central question, “How did this happen?,” may seem of merely academic interest when nations of the world are committing themselves to ever-more-ambitious programs to meet the “threat” of global warming, in fact it cuts to the heart of the problems we will face over the next decades, should these policies be implemented.

For if Mr. Salmon and thoughtful critics like him are correct about the unlikelihood of significant warming, the policies will be “successful”; that is, the warming “predicted” by the computer models will not occur. Never mind that we will have expended vast resources to address a non-problem, and behaved like the man in midtown Manhattan who constantly whistles to keep the elephants away. The “men of courage” will no longer be those who spoke of what might be, but those who apparently averted what might have been.

Such an outcome can only be devastating for the integrity of science, given the compromised position too many scientists have already put themselves in with regard to global warming. On this point Mr. Salmon is perhaps too charitable. What is noteworthy is not that a few “experts” seek fame and fortune by creating this issue, or that politicians eager for a cause allow themselves to be misled, but that so many serious researchers remain silent in the face of distortions such as the ones Mr. Salmon documents. While they no doubt have better things to do than appear on TV and sign “anti-greenhouse” statements, it would be no surprise if many of these researchers took a wait-and-see attitude toward the political campaign of their more notorious colleagues. After all, the publicity has already brought more dollars and vastly more prestige to a relatively neglected scientific speciality.

Thus, the greatest risk of “greenhouse anxiety” is that it will teach scientists the same lesson (but with higher stakes) that their trendy academic colleagues in the humanities and social sciences are busy dispensing: the search for truth means nothing, and a grab for power everything.

Charles T. Rubin
Duquesne University
Pittsburgh, Pennsylvania

_____________

Jeffrey Salmon writes:

In my article I argued that there is no solid evidence to support the theory that the earth is warming because of man-made greenhouse gases. Michael Oppenheimer and Allan Frei and Stuart Gaffin say the proof of the greenhouse theory is to be found in the record of ancient climates, preserved in bubbles of air trapped in thick sheets of ice in Greenland and Antarctica. The ice records go back more than 150,000 years and show a clear connection between changes in carbon dioxide and changes in temperature. When CO₂ goes up, the earth’s temperature increases; when CO₂ goes down, the earth’s temperature falls.

But my critics fail to mention an important fact. They would have the reader believe that CO₂ caused the temperature change, but the evidence suggests that the temperature changed first and the CO₂ changed roughly 1,000 years later. Since temperature shifts precede CO₂ changes, CO₂ cannot be the cause either of rising or falling temperatures. In fact, the reverse seems to be true: the CO₂ changes may be the effect of temperature changes; when the earth’s temperature rises the oceans must give up some of their dissolved CO₂ to the atmosphere, just as a bottle of soda loses some of its fizz when warmed. By itself, then, the correlation between rising CO₂ and rising temperature in the record of the earth’s climate provides no evidence at all of a greenhouse effect.

This turns out to be true also for the recent changes in CO₂ and temperature. Scientists at Bell Laboratories have carefully compared the month-by-month changes in CO₂ and temperature since the 1950’s, and find that the temperature changes occur first and the CO₂ changes occur about five months later.

Along with Mr. Oppenheimer, Messrs. Frei and Gaffin also argue that these ice cores reveal that dramatic temperature swings are possible, and that these wild swings are accompanied by leaps in the amount of atmospheric CO₂. “Pumping up the greenhouse gases,” Mr. Oppenheimer says, might “terminate” our current stable climate system. But since the ice-core data show that CO₂ levels shift after the climate changes, this appeal to evidence from “ancient air trapped in ice cores” is meaningless.

Messrs. Frei and Gaffin say I “refuse to acknowledge the extent to which the [computer] models have been validated,” but fail to offer a single example of that validation. In fact, the computer models strike out on almost every important point. The models predict that, in response to the accumulated greenhouse gases in the atmosphere in the last 100 years, the temperature of the earth should already have risen by at least one degree. And they predict, further, that the Northern Hemisphere should have warmed more than the Southern Hemisphere; that the U.S. should have warmed more than the Northern Hemisphere as a whole; and that high latitudes—especially the Arctic zone—should have warmed most of all. Not a single one of these predictions has been borne out by temperature measurements.

Messrs. Frei and Gaffin object to my relying on the measurements of what the earth actually did in the last 100 years as a basis forjudging the greenhouse theory. They state that the 1940’s-1960’s cooling period does not contradict the theory that rising levels of CO₂ cause global warming because this chill could be explained by “other major climate changes such as solar cycles and volcanic dust.” How convenient. If other factors, such as solar cycles, can cause the temperature to go down, they can also cause the temperature to go up. In other words, there is no reason to connect even the modest half-degree of warming over the last 100 years with the greenhouse effect. Yet in James Hansen’s congressional testimony in 1988, he used that half-degree of warming to support his claim that a man-made greenhouse effect had already set in. He did not mention that natural causes of warming, like the sun, might be responsible, and that the greenhouse effect might be a negligible factor.

Mr. Oppenheimer argues that my dismissive attitude toward policies to cut CO₂ emissions “contrasts sharply with independent multidisciplinary assessments” such as the one published by the National Academy of Sciences (NAS). Here are two sentences from the NAS study:

Neither the available climate record nor the limited capabilities of the climate models permit a reliable forecast of the implications of continued accumulations of greenhouse gases in the atmosphere. Neither do they permit an assessment as to whether the increase from 1890 to 1990 in global average temperatures can be attributed to greenhouse gases.

There could be no clearer confirmation of my conclusion.

Messrs. Frei and Gaffin claim that when referring to global warming the “overwhelming majority” of scientists would never use the extreme language I attribute to them, such as “catastrophic.” As I noted in my article, 700 members of the National Academy of Sciences signed a statement sponsored by the Union of Concerned Scientists warning that burning fossil fuels could cause a 9°F temperature rise which “could have catastrophic consequences for climate. . . .” And the first line of the prologue to Michael Oppenheimer’s global-warming book, Dead Heat, reads: “Humanity is hurtling toward a precipice.” “Catastrophic” and “hurtling toward a precipice” are pretty strong language.

Bernard D. Goldstein asserts that I “fail the basic test of journalistic credibility” by omitting important parts of the global-warming argument, in particular “the salient fact that the mid-range projection of the rate of warming of the biosphere appears to be unprecedented” in human history. Far from failing to present this fact, I made it the main point of my article. It is true that the projections of warming are unprecedented, but the observed temperature rise is nil. Precise satellite measurements of global temperature show that there has been no more than a few hundredths of a degree of warming in the last fifteen years, but the computer projections indicate that the earth’s temperature should have risen by a substantial fraction of a degree during this period.

Finally, Dr. Goldstein thinks that this year’s sweltering summer should make me take global warming more seriously. Pointing to one summer’s warm spell as an indication of the horrors of the greenhouse effect is one of the shallowest arguments in the environmentalists’ lexicon. I will assume Dr. Goldstein was smiling when he wrote that sentence.

I am grateful for the letters of Donald Feldstein and Charles T. Rubin. Mr. Feldstein raises an important question about the intellectual honesty of the environmental movement. His examples—nuclear winter and population growth—indicate the ways the movement reacts when the facts go against it. One method, which was used in the nuclear-winter saga, is to forget the problem and move on to more fertile soil. Global cooling gave way to nuclear winter, which in turn gave way to global warming, which may in time give way to a new horror.

Mr. Rubin’s comment on scientific integrity goes to the core of the political issues discussed in my article. Only the members of the scientific community have the knowledge and credibility to challenge the politicized science that is now commonplace in the environmental arena. But the scientific community has been largely silent—a silence Mr. Rubin attributes to the fact that dollars follow eco-alarms and no one wants to ruin someone’s research funding. Yet the consequence of this silent complicity in the promotion of bad science is that one day scientists may be held in the same regard as lawyers.

A possible solution, suggested by Mr. Rubin himself in other writings, is to diversify sources of funding. Our government now spends over $1 billion a year on greenhouse and climate-change research. With that amount of government funding pouring into this one field of research, it is no wonder that the science of climate change has been politicized.