Sources: T. Goldfarb (Ed.). Taking Sides: Clashing Views on Controversial Environmental Issues. Guilford, CT: Dushkin (7th edition, 1997). A similar, but much longer essay, can be found in Population and Environment: A Journal of Interdisciplinary Studies 17: 459-489 (1996).


The Greenhouse Effect Revisited

Moti Nissani


Now we can only wait till the day, wait and apportion our shame.

These are the dykes our fathers left, but we would not look to the same.

Time and again were we warned of the dykes, time and again we delayed:

Now, it may fall, we have slain our sons, as our fathers we have betrayed.

Rudyard Kipling


Michelangelo, The Deluge, 1509 Delugeb.jpg (389449 bytes)



A recent, rather typical, review (Beckerman & Malkin, 1994) argues that even if the greenhouse threat is real, even if temperatures rise and low-lying lands must be protected forever by an enormous system of dikes, such unlikely occurrences do not justify "imposing vast costs on the present generation rather than helping developing countries overcome the environmental problems that they are facing today" (for similar views, see also Firor, 1994; Moore, 1995, Nordhouse, 1994, p. ix; Singer, Revelle, & Starr, 1993). The present essay argues that anyone willing to cross disciplinary boundaries can easily ascertain that this surprisingly popular viewpoint is mistaken.




By absorbing more than 99% of the sun's ultraviolet radiation, stratospheric ozone shields life on Earth from this radiation's harmful effects. A depletion of stratospheric ozone might allow more ultraviolet radiation to reach the ground and disrupt natural ecosystems, lower agricultural productivity, suppress the human immune system, and raise the incidence of skin cancer and eye cataracts (American Chemical Society, 1978, p. 231).

CFCs (chlorofluorocarbons) were invented in 1930. Gradually, these nontoxic, odorless, inert compounds came to be used as coolants (in refrigerators and air conditioners), as foam-blowing agents (in such things as takeout food trays and cups), as propellants in spray cans, and as cleaning agents of computer chips.

In 1974 scientists began to suspect that these long-lived creations reach the stratosphere and destroy ozone. Such concerns were dismissed out of hand by governments, CFC makers, and their paid experts. A heated controversy followed, and by 1978 only the United States, Canada, Sweden, and Norway banned the use of CFCs--and only in aerosol sprays. So atmospheric CFC levels kept inching upwards. Unexpectedly, by 1985, and thanks only to the fortuitous presence of permanent scientific stations in Antarctica, alarming temporary reductions in springtime ozone levels over Antarctica were reported. By 1986, the CFC/ozone link was reasonably established. Later, less massive depletions of stratospheric ozone were detected throughout the globe. Nonetheless, corporations still engaged--successfully--in delaying tactics. As a result, by 1990 the world's nations did agree to stop production of CFCs--by the year 2000.

By 1992 the global shield had lost 5% of its ozone. By then, the world's nations agreed to advance the virtual phaseout date (1996 for rich countries, 2006 for poor; Houghton, 1994, p. 143) and to replace CFCs with somewhat (Asimov & Pohl, 1991, pp. 129-133) less destructive materials. In some cases, CFCs might even be replaced with readily available, cheaper, and environmentally benign substitutes (for instance, reusable glass cups instead of CFC-containing styrofoam cups; ammonia as a refrigeration agent instead of CFCs, cf. Ross, 1994). By March 1995, ozone concentration above Europe and the United States fell by 10% to 20% below 1979 levels (Monastersky, 1995). Ozone levels are expected to reach their lowest levels over the next decade, and to fully recover by 2066.

In the next fifty years, 240 million human beings might contract skin cancer as a result of ozone depletion, of which 4 million might die. Eighty million might develop eye cataracts, of which many might become blind. Other possible effects are suppression of the immune system, threats to the Antarctic food chain, damage to ecosystems and agriculture, and extinctions of some wild species. Some of these effects are already being felt, especially in southern countries like Australia and Chile.

Struck by the unprecedented nature of the global phaseout decision, some people see the ozone saga as a remarkable victory for human rationality. We are, they say, at the dawn of a new age.

Others see the exact same events as proof of collective misconduct (e.g., Asimov & Pohl, 1991). They question the advisability of letting these Frankenstein monsters (CFCs) loose on the environment in the first place. They wonder about the 22-year lag from indictment (1974) to partial lockup (1996) and about the 11-year interval from discovery of the Antarctic hole to the partial ban. They note that CFCs have not been indispensable to the world's economy or to average quality of life. They frown upon the unremitting use of CFCs in such things as coffee cups despite the availability of cheap substitutes (and despite the unpleasant taste of hot drinks in styrofoam cups). They draw attention to CFCs' well-known and decisive contribution (second only to CO2) to a second major environmental threat (enhanced greenhouse effect), and to the prospective legacy of one-third of a billion needless tragedies left in the wake of this "victory for scientific rationality acting in the realm of human affairs" (Hobson, 1993, p. 11).

Such skeptics find the closest parallel to the ozone tale in science fiction. For instance, in Karel Capek's humorously pessimistic War with the Newts, exceptionally clever and prolific salamanders are encountered in some far off bay. At first their discoverers offer them knives and protection from sharks in exchange for pearls. Gradually, however, many of the world's nations avail themselves of these creatures for other purposes, including war. In a few years, the salamanders run out of living space. To accommodate their growing numbers, they flood countries, one at a time. To do this, they need supplies from countries elsewhere and from merchants of the soon-to-be ravaged country itself. Needless to say, the salamanders have no trouble securing everything they need. At the end, humanity is on the verge of sinking and drowning; not so much by the newts, but by its greed, shortsightedness, and colossal stupidity.

This and other tales (e.g., Capek's R.U.R, Kurt Vonnegut's Cat's Cradle) imply that the world is not a wholly rational place. Indeed, the place and date of publication of War with the Newts--Czechoslovakia, 1935--throw some light on the origin of this tale. At that time, or a short time earlier, a few English, French, or American divisions could have invaded Germany, sent Hitler into early retirement, and saved humanity from disaster. Others besides Capek appealed for preemptive action. But Western politicians worried about the next elections and disregarded the more distant future. They remembered their petty quarrels and forgot their common, and far more sinister, foe.

Without trying to resolve this historical controversy about ozone abatement and human rationality, let us shift our focus to the greenhouse effect.



Sunlight can go through the atmosphere--that is why we see the Sun. Sunlight then warms the ground and lower atmosphere, which then emit heat, a form of radiation one can feel but not see. In physical terms, heat radiation has a longer wavelength than visible light. On the spectrum it falls just below visible red, hence it is called infrared radiation.

Now,CO2 and a few other greenhouse gases in the atmosphere allow most sunlight to go through them. When this light reaches the ground or lower atmosphere, it is converted in part into heat which is then reflected back towards space. CO2 and other greenhouse gases trap some of this heat and irradiate it back to the ground, thereby delaying its escape into space.

Earth, then, is livable thanks to its naturally occurring greenhouse gases: water vapor, carbon dioxide, methane (natural gas), nitrous oxide (laughing gas), and ozone (Hare, 1993, p. 11). Like the glass of a car with rolled-up windows (but through a different physical process), these gases trap more heat than light. Our planet is thus a sleeping giant, comfortably blanketed by its own set of greenhouse gases. Without these atmospheric gases, Earth would be 60 degrees F colder than the current average of 59 degrees F, hence lifeless.



The chief culprit in changing Earth's greenhouse balance is CO2. Our civilization is burning enormous quantities of coal, gas, oil, and wood, thereby releasing in CO2 to the atmosphere. Forest burning similarly releases and CO2 transforms trees from longterm consumers of CO2 to short-term producers. As a result, since 1860 CO2 levels have gone up by 25% (Cherif & Adams, 1994, p. 30), with more than half of this increase taking place since 1959! (Brown, Kane, & Ayres, 1993, p. 68).

In the future, other factors may further exacerbate this problem. For instance, ozone-related increases in ultraviolet light (Smith, 1995), as well as rising pollution levels, may reduce the capacity of the world's oceans to sustain small, floating aquatic plants, thereby further disturbing the CO2 balance on Earth.

As we have seen, human-made CFCs are still being discharged into the atmosphere, and CFCs trap heat too. Other important enhanced greenhouse gases are methane and nitrous oxide. In absolute terms, the increase in CFCs, methane, and nitrous oxide has been comparatively small, but pound for pound, some of these gases are more powerful heat absorbers than CO2. Their combined warming effect is equivalent to that of a 15% rise in CO2. So the Earth's atmosphere contains now the equivalent of 40% more CO2 than it did in 1960 (Beckerman & Malkin, 1994).



Ecosystems are comprised of numerous living and nonliving elements. We are often ignorant of the existence of some of these elements, and we only partially comprehend others. All these elements, in turn, form an intricate web of interconnections and feedbacks, a web which often eludes our grasp. As if this is not enough, we have also good reasons to suspect that ecosystems often behave chaotically--a change in one or another of their seemingly insignificant components may, in the long run, profoundly alter them.

For these reasons, we can never be absolutely sure that the biosphere is changing in the direction predicted by the greenhouse theory. There is, however, a growing body of evidence suggesting that this may be the case. Here we cannot go into all the detail, but merely mentions some developments which be reasonably be viewed as harbingers of global warming (Kerr, 1995):



These continuing trends would likely have some favorable outcomes. For instance, because low CO2 levels currently limit the pace of photosynthesis, all other things being equal, rising levels of this gas may increase the productivity of farms, forests, and marine systems in some regions. Likewise, Siberians, Greenlanders, and other northerners might welcome a warmer climate.

The best scientific bet, however, is that, on balance, the effects would be troublesome. Temperatures may have already risen by about 1ºF, explaining perhaps the unusually hot summers and weather extremes of recent years. In fifty years, if we continue the unbridled release of greenhouse gases into the atmosphere, temperatures might go up by some 6ºF. This increase may lead ocean water to expand and rise. Ocean water may rise, as well, because higher temperatures may melt the polar ice caps. Sea levels may thus rise by 17 inches by the year 2070 (Brown, Kane, & Ayres, 1993, p. 68) and submerge low-lying areas such as Louisiana. Unable to cope with the unprecedented pace of climatic fluctuations and change, some wild species might perish (Gates, 1993). Climates may shift, perhaps converting once-prosperous agricultural areas into deserts. Higher temperatures, weather extremes, flooding of coastal areas, regional changes in rainfall patterns, and an unstable seasonal cycle (Thomson, 1995, p. 66) may reduce agricultural, forest, and natural productivity (Manning & Tiedemann, 1995; Rosenzweig, 1994). Tropical climates and diseases may spread and summer heat waves may become more common (Stone, 1995). Oxygen levels in the atmosphere and oceans may decline. Humanity may be visited more often by devastating storms, droughts, and other weather extremes. History likewise shows that, at times, global and regional temperatures profoundly affect human affairs; climatically, economically, or politically stressed societies are especially vulnerable (Brown, 1994).

An even worse specter cannot be altogether ruled out. As the Earth heats up, more water would turn into vapor, and vapor is a greenhouse gas. Stored CO2 might likewise escape from ocean rocks and shells, and stored methane might escape from vast permafrost regions (Cherif & Adams, 1994, p. 30). Beyond a certain point, the process may get out of control. The planet Venus tells us how far such a runaway process can go--hellish temperatures, enormous surface pressures, and a distorted landscape.



Owing to the complexities of Earth's biosphere and climate, all predictions are shrouded in doubt. It could be that, as I revise these words, our planet's temperatures are imperceptibly rising. For argument's sake, let us arbitrarily say that there is a 1 in 2 chance that this is occurring. If this warming continues, in a few decades it may lead to adverse (say, 1 in 10), beneficial (say, 1 in 10), or neutral (say, 8 in 10) consequences for the quality of life on this planet. Finally, there is the specter of consequent extinction of life on Earth in a few centuries as a result of human-caused, unchecked global warming (say, 1 in 100). Amidst all these uncertainties and arbitrary numbers we can be sure of one thing: the uncertainties will remain. Should we then cross our fingers, allow present trends to continue, and let chance decide our fate?

Given the stakes, some people would argue that we should act to avert the possibility of disaster, regardless of cost. Others might argue that we should act only if the requisite policies do not divert resources from even more urgent tasks. No one, however, would openly argue that we should do nothing if the requisite policies not only avert the greenhouse threat, but if they also have many other beneficial environmental, public health, and aesthetic consequences and if they can save our species billions of dollars every year. If such policies were shown to exist, the greenhouse debate would, in principle, come to an end. Who could oppose beneficial and remunerative policies? Uncannily enough, although such policies have been readily available for decades, they are not being followed.

As we have seen, CFCs contribute to as much as 24% of the expected warming. Because they are also the chief culprit in the ozone layer tragedy, they will be soon partially banned. Over the next century, their concentrations in both the lower and upper atmosphere will decline. Tardy or not, the CFC ban would slow down the suspected warming trend.

The needed additional steps have been championed for decades by many writers. Among the most indefatigable, articulate, and insightful advocates of this sustainable-earth path is Amory Lovins. Here is a typical refrain:

Global warming is not a natural result of normal, optimal economic activity. Rather, it is an artifact of the economically inefficient use of resources, especially energy. Advanced technologies for resource efficiency, and proven ways to implement them, can now support present or greatly expanded worldwide economic activity while stabilizing global climate--and saving money. New resource-saving techniques--chiefly for energy, farming, and forestry--generally work better and cost less than present methods that destabilize the earth's climate (Lovins & Lovins, 1991, p. 433).

Such steps, sustainable-earth advocates say, could cut emissions of CO2 by more than 60%, of methane, by 17%, and of nitrous oxide by 75%. Such claims are usually dismissed by politicians and journalists, by scientists and other academics who believe that the greenhouse threat is a chimera requiring no action whatsoever, by reputable economists who believe that it might cost as much as 4 trillion dollars to avert the greenhouse danger (Schneider, 1990, p. 188) and also by many informed science writers who are committed to removing the greenhouse threat (Franck & Brownstone, 1992, pp. 145-6).

Such widespread beliefs seem to make a mockery of Lovins' claims that increased energy efficiency can solve the greenhouse problem and save money. Are his claims absurd? My answer to this is simple: these claims are not absurd, but entirely correct.

To begin with, assertions of combined savings and safety are supported by many other researchers. Also, the worst greenhouse offender--the United States--does not use energy as efficiently as some other equally prosperous countries. By catching up with existing Swedish standards, for instance, the United States could vastly reduce greenhouse emissions, save trillions, and begin to heal its citizens and trees, fields and streams, water and air.

A similar point concerns history. Compared to real energy expenditures in 1973, and thanks to conservation measures implemented since then, energy conservation is already saving the United States at least $100 billion a year. Twenty years ago many economists opposed energy conservation for 1001 reasons. They have thus managed to slow down this historical process, but common sense, and the logic of a mixed economy, tilted the balance and proved them wrong.

Thus, the sustainable-path position boils down to nothing more outlandish than a plea to all nations to accelerate this salutary historical trend, in part by following the proven examples of prosperous, energy-efficient, countries like Sweden and Japan.

The sustainable-earth package is comprised of numerous measures, of which only a few can be discussed or mentioned here:

1. "Removing a 75-watt incandescent lamp [the familiar household light bulb] and screwing into the same socket a 15-watt compact fluorescent lamp will provide the same amount of light for 13 times as long, yet save enough coal-fired electricity over its lifetime to keep about a ton of CO2 out of the air (plus 8 kg of [polluting and acid rain-causing] sulfur oxides and various other pollutants). . . .Yet far from costing extra, [in the long run each lamp] . . . saves tens of dollars more than it costs" (Lovins & Lovins, 1991, pp. 437-8; see also National Academy of Sciences, 1994, pp. 217).

2. A 1989 study by the U.S. Department of Energy describes "15 proven, readily available, improvements in car design. These, plus two more equally straightforward improvements," would not involve any changes in car size, safety standards, or acceleration, yet they could reduce fuel consumption by 35%. And this is a mere drop in the bucket. Already available prototypes such as the Toyota AXV (89 mpg city; 110 mpg highway), prove that cars more than three times as efficient as the world's fleet can be at least "as comfortable, peppy, safe, and low in emissions as today's typical" new car (Lovins & Lovins, 1991, p. 446).

3. According to the National Academy of Sciences, "a consensus is emerging in the engineering, utility, and regulatory communities that, even when past efficiency gains and projected population and economic expansion are considered, an additional, significant reduction can be made in U.S. residential and commercial electricity consumption. This reduction is not expected to sacrifice comfort levels and will cost less--in many cases, substantially less--than the purchase of new sources of power" (1992, p. 204). The savings in both carbon emissions and dollars can be readily accomplished through such simple steps as adding triple pane windows to existing buildings and improving the design of hot water tanks. For the United States alone, such measures would cut total CO2 emissions by some 18%, and would save some $56 billion per year (National Academy of Sciences, 1994, p. 240). By itself, this figure is striking from the economic standpoint, if from no other: every year, the average American household could save hundreds of dollars through this step alone.

Space does not permit the continuation this magic list (cf. Nissani, 1996). At this point, suffice it to mention such other proven measures as paper recycling (Lovins & Lovins, 1991, p. 474; Miller, 1994, p. 402), cogeneration (Miller, 1994, p. 450), reduction of wasteful methane emissions (Heilig, 1994, p. 131), construction ofnew small-scale hydroelectric plants (Miller, 1994, p. 464), solar cells (Keepin, 1990, p. 316), and other solar technologies (Smith, 1995, p. 40, Asimov & Pohl, 1991, pp. 226, 230).

Scoffers at the sustainable-earth position often treat the greenhouse problem in isolation from everything else that ails our planet and species. They forget that while academia can be gainfully fragmented into disciplines, the world cannot: reality is a web, not a collection of parallel lines. We have seen already that the prospective CFC ban would markedly aid both the ozone depletion problem and the greenhouse threat, but this combined effect is a mere peanut in Santa Lovins' famous briefcase. Besides averting the greenhouse and ozone threats, the proposed measures would entail worldwide savings of untold billions of dollars and countless natural resources. They would improve our material quality of life, reduce pollution, cut severe environmental and health impact of coal use (e.g., black lung disease, land subsidence), improve human health, eliminate future acid rain problems (which are currently aging buildings and monuments, damaging forests, and killing fish in thousands of lakes and streams). Furthermore, these measures would diminish urban smog and help clean up our air, water, and food. They would reduce the incidence of tragic and costly floods, storms, and, perhaps, other natural disasters. They may improve the quality of topsoil and farmland, thereby increasing longterm agricultural productivity. They would gradually lead to the elimination of costly and unsafe nuclear power. "In sum, informal estimates (of EPA) . . . suggest that most--perhaps around 90%--of the problems EPA deals with could be displaced, at negative cost, just by energy efficiency and by sustainable farming and forestry. That is a pleasant by-product of abating global warming at a profit" (Lovins & Lovins, 1991, p. 518). Moreover, the sustainable-earth path would considerably slow down the worrisome prospect of massive species extinction. It would raise economic competitiveness (for instance, greater energy efficiencies partially explain low production costs of Japanese cars) And it would reduce dependence on foreign energy supplies.



Humankind's greenhouse policies defy common sense. If the technical solutions are so easy, profitable, and beneficial, why are they not adopted? Why did President Clinton, when announcing his administration's greenhouse position in late 1993, agree to do virtually nothing? Is it mere ignorance on the part of politicians, as Lovins & Lovins suggest (1991, p. 525)? Is it greed (humanity spends one trillion dollars a year on coal, oil, and gas alone; cf. Leggett, 1990, p. 4)? Is it yet another manifestation of Garrett Hardin's (1968) tragedy of the commons? Is it inertia? The answers to these important queries--answers which rival in number and ingenuity Lovins' energy-saving gizmos--cannot be explored here (cf. Hardin, 1968; Nissani, 1992, 1994).

In the meantime, it would appear that the greenhouse threat is real; the recipe for health and wealth simple; the wisdom to use it, absent. To justify their faith in humanity's luck, the optimists can rightly cite the historical record. But to maintain their faith in humanity's rationality, they must show that the probability of disaster is close to zero and that the costs of prevention are well above zero. Until this feat is accomplished, skeptics would go on insisting that all but the details of humankind's environmental follies had been predicted long ago in Capek's War with the Newts.

The last chapter in humanity's greenhouse saga remains to be written, perhaps long after cacti have grown over our cheeks. Until then, one's future projections depend less on science and more on one's temperament: on whether one sees the world as turning towards dawn or dusk. Who knows? We may continue to emit greenhouse gases forever and remain as cool and comfortable as we have ever been. We may come to our senses in time, act, and vanquish the threat. Inadvertently, we may remove the threat. We may sweat and survive. Or we may sink and drown.




This essay has been adapted, with the kind permission of the publisher and editor, from an essay in Population & Environment: An Interdisciplinary Journal. I thank Donna Hoefler-Nissani, Virginia Abernethy, Ronald Aronson, and students of ISP 601 for their generous comments.



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