Rarely a week goes by without a major newspaper or magazine focusing attention on “global warming,” a theory that suggests the increasing concentration of greenhouse gases in the lower atmosphere will result in an increase in the average global temperature. Although any potential increase in temperature may be counterbalanced by other changes, the net result is uncertain; and scientists, environmentalists, and government entities seem unable to agree on the degree of threat or the necessity for action. There is no scientific consensus in support of a global warming threat among the scientists specializing in atmospheric physics or climatology.

Some facts are not in dispute. Greenhouse gases do trap solar energy within the atmosphere and increases in their concentration would cause Earth to retain more of the sun’s heat. There is also no scientific dispute that the planet’s climate has varied widely over the past million years. Indeed, recent research suggests that Earth’s climate has been erratic for the past 100,000 years and in the 10,000 years that human civilization has evolved the climate has been unusually stable. The fact is, experts have no idea how mankind’s injection of greenhouse gases into the atmosphere will affect the complex and obscure worldwide climate machine.

The term “greenhouse effect” refers to a natural phenomenon that occurs when certain gases in the atmosphere, principally water vapor and CO2, trap heat radiating from the earth’s surface. Without the greenhouse effect, the earth’s average temperature would be roughly 0° instead of just over 59° and life as we know it could not exist on earth (USEA 26).

“Global warming” is caused by a buildup of “trace gases” in the Earth’s atmosphere. These trace gases—carbon dioxide (CO2), methane (CH4), and chlorofluorocarbons (CFCs)—surround earth, acting like the glass on a greenhouse: they allow sunlight to come in, then trap much of the heat so that it does not escape.

In “Global Warming: Are We Entering the Greenhouse Century?” Stephen Schneider maintains that to date, these greenhouse gases have trapped about two watts per square meter of extra radiative energy near the Earth’s surface since the Industrial Revolution, “equivalent to the power of a small Christmas tree bulb in every square meter of earth” (38). The knowledge does not exist, however, to translate those two watts of heating to an equivalent temperature rise.

The World Commission on Environment and Development (WCED) reports in Our Common Future that in recent years, trace gases have been accumulating from energy production, automobile exhaust, the burning of forests, energy production, and the use of products containing CFCs such as aerosol sprays, refrigerators, and air conditioners (23). WCED maintains that carbon dioxide (CO2) is the most problematic of the trace gases because it is the most abundant and the most difficult to reduce or control.

The pre-industrial concentration of CO2 was about 280 parts of carbon dioxide per million parts of air by volume. This concentration reached 340 in 1980 and is expected to double to 560 between the middle and the end of the next century (174). The danger is that as trace gases, particularly CO2, continue to build up, more heat will be trapped and Earth’s climate will continue to warm up, causing a global climate change that will disrupt worldwide weather patterns in unforeseeable ways (32). While it seems unlikely that all the effects of global warming will be harmful, it is impossible to predict which countries may gain, which lose, and how.

Some authorities maintain that at current rates, the Earth’s average surface temperature could climb from two to nine degrees Fahrenheit over the next century. A seven-degree warming nearly equals the temperature difference between the end of the last ice age and the present (Singer 20). In that case, however, nature had 10,000 years to slowly adjust to the climate changes.

Stephen Schneider, head of the Interdisciplinary Climate Systems Section of the National Center for Atmospheric Research, states that a climate change of several degrees in just a century is at least 10 times, and perhaps 100 times, more rapid than an average natural change (Global 144). Mr. Schneider warns that a change this rapid would cause an incredible disruption to natural ecological systems, human agriculture, and water supplies. In some areas, he says, warmer temperatures would increase the rate of evaporation, leading to more droughts. At the same time, the melting of the polar ice cap would cause the world’s oceans to rise, flooding the Earth’s coastal areas where more than half the world’s population lives (145).

Global warming could also cause heat-related health problems. George Sanderson, Deputy Director of Information and Public Affairs for the United Nations Environment Programme, warns that global warming could allow tropical diseases to affect nontropical populations, causing heat-related stress and illness. Malaria, polio, yellow fever, dengue fever, tetanus, cholera, and dysentery flourish in hot, humid weather, which will become more common in the United States (36). A warmer climate would also provide an ideal atmosphere for the toxic side-effects of bacteria and mold growth, resulting in more contaminated and spoiled food (38).

While these dire warnings of the dangers of global warming have only surfaced in the last few years, the global warming phenomenon was actually discovered over 100 years ago. In his article “From the Nuclear Frying Pan into the Global Fire,” Spencer Weart provides a comprehensive account of the global warming issue. Mr. Weart states that the subject of global warming first surfaced in 1827 when French physicist Jean-Baptiste Fourier suggested that the earth is warm because air traps heat. Then, in 1896 a Swedish geochemist named Svante Arrhenius showed that adding carbon dioxide to the atmosphere would gradually raise the earth’s temperature. Arrhenius had enough “spectroscopic information” to estimate that doubling the amount of carbon dioxide in the air could warm the world by four to six degrees Celsius and that industrial output of carbon dioxide had already reached a level comparable to the amount that circulated naturally (19).

The subject did not surface again until an unknown British steam technologist, G.C. Callendar, presented a paper to the Royal Meteorological Society in 1938 which calculated that the planet was getting warmer because of an increase in atmospheric carbon dioxide (Weart 21). In 1956, Gilbert Plass of Johns Hopkins University published new calculations indicating that industrial carbon dioxide would raise the world temperature and the same year, a group at Princeton programmed a computer model which produced maps of air movements that looked like real weather patterns (23).

The new interest in weather predictions prompted scientists to borrow a measurement tool from nuclear physics that used Carbon 14 to estimate how much carbon dioxide in the atmosphere came from burning fossil fuels. Using this new technology, Charles Keeling planted instruments in the clear air atop Mauna Loa in Hawaii and by 1961 he began recording the gradual rise in global carbon dioxide (24).

By the 1970s, scientists were constantly turning up more factors which had to be taken into consideration when calculating global warming. So many things looked significant—rain forests, ocean currents, stratospheric haze—not to mention rice paddies, cow gas, and refrigerants (Weart 25).

By the 1980s, new computer models consistently predicted that doubling carbon dioxide would raise temperatures between two and four degrees. Then, in October 1985, world attention was focused on the issue when a group of scientists from 29 industrialized and developing countries organized by the World Meteorological Organization, the UN Environment Programme, and the International Council of Scientific Unions met in Villach, Austria to examine the latest evidence on the greenhouse effect. They concluded that climate change must be considered a “plausible and serious probability” (qtd. in WCED 27). This position was not accepted by the entire scientific community, however, and opinion remains divided on whether or not global warming is actually occurring.

The dispute can be simplified to two positions as exemplified by Andrew Solow of the Woods Hole Oceanographic Institution and John Pike of the Federation of American Scientists. In his article “Global Chilling,” Mr. Pike maintains that the danger is that “by the time you have signals so unambiguous that nobody is going to argue with them, you're in deep, deep doo-doo” (45). Mr. Solow, on the other hand, is quoted in a Time article, replying, “It’'s also possible that the U.S. will be economically impoverished…in anticipation of a greenhouse warming that never arrived” (Linden 68).

This chart, which shows temperature fluctuations from 1882 to 1990 with corresponding atmospheric carbon dioxide levels, provides ‘fuel’ to both sides of the dispute. Some scientists fear that the century-long increase in temperature is partly due to rising carbon dioxide levels. But skeptics point out that the real increase over the last 100 years occurred previous to 1940, when humans started generating greenhouse gases. The chart shows that between 1940 and 1975 there was a decrease in global temperature with a sudden increase between 1975 and 1980.

Actually, if the temperatures for the last 50 years—as we began adding greenhouse gases to the atmosphere—are analyzed, Dr. Fred Singer, an atmospheric and space physicist and professor of environmental sciences, points out that no real temperature increase from 1940 to 1990 can be seen. He maintains that changes will be gradual and nowhere near the estimates of the computer climate models (17).

Robert Balling, the director of the office of climatology at Arizona State University, believes the greenhouse effect is far from probable. In the January 1994 issue of the Alberta Report, he states that satellite measurements taken since 1978 show no global warming whatsoever and cites a study which found that the Arctic has actually cooled sightly over the last 50 years (Fuller 16).

However, these statements directly contradict recent study results indicating that areas of Arctic tundra are now releasing CO2, which indicates that the tundra is beginning to thaw. An article in Earth magazine states that over the past century, scientists have detected a rise in surface air temperatures and a warming of the permafrost over Arctic Alaska, Canada, and possibly northern Siberia (McInnis 20-21).

Dixie Lee Ray, professor of zoology at the University of Washington, contends that the recent temperature changes are normal and do not portend massive global warming. Ms. Ray maintains that the temperature readings do not show a relationship to the slow but increasing carbon dioxide in the atmosphere over the last 50 years (38) and that“"This conclusion is borne out by 10 years (1978 to 1988) of temperature readings taken daily over both land and ocean surfaces of the Earth from the space satellite TIROS II” (42).

Additional evidence, she maintains, is provided by plants. In February 1990, the Department of Agriculture's National Arboretum published a hardiness zone map (39). This map, which has not been revised since 1965, shows areas where crops can be safely planted in order to avoid winter frost damage. Says Marc Cathey, the National Arboretum director, “The trees and the plants have been telling us unambiguously that the U.S. climate has been cooling, not warming” (qtd. in Ray 39).

In addition, the effect of increased carbon dioxide levels in the atmosphere has actually been heralded as an agricultural blessing by many. Initial studies suggested that a high CO2 environment would enhance plant growth. This ‘fertilization effect’ is expected to be particularly pronounced if plants have plentiful supplies of nutrients, light, and water. Plants growing larger in a CO2-rich atmosphere would draw more CO2 from the atmosphere, lowering the ‘warming potential’ (Idso 85).

In experiments conducted at Harvard University; however, long-term studies indicated that while plants growing under increased CO2 conditions initially show increased photosynthesis, over time, rates lower almost to the level of plants growing under today’s conditions. The speculation is that increased photosynthesis results in an excess accumulation of starch that hinders plant growth or that a biochemical feedback slows down photosynthesis (Bazzaz 69). The study also showed that plant growth was dramatically influenced by the amount of light and nutrients provided and that elevated levels of CO2 had a very mild effect when a plant received little light or few nutrients. They also found that tree seedling communities were not more productive in a CO2-rich atmosphere when different species were grown together (70). The reasons for these findings are inconclusive and more studies are necessary before the effects of a large accumulation of CO2 in plants is understood.

While it is argued that increased levels of CO2 may have some beneficial effects, computer-generated weather simulations have indicated that it will cause many more problems. A Continuum article titled “Global Warming: It’s Here For Real—Or Is It?” states that the idea of programming computer models to predict weather patterns began in the 1950s but was given very little attention until the summer of 1988, when NASA climatologist James Hansen testified before Congress that his computer model verified the fact that the planet was warming up (29). These computer models are constantly being improved, and the newest incorporates various feedbacks to allow for increased water vapor in the atmosphere which would cause rapid changes in trace gas compositions (Khalil 139).

A minority of world-class atmospheric scientists disagree with the global warming scenarios projected by these computer models. Andrew Solow, a statistician at the Woods Hole Oceanographic Institution, maintains that the computer models used to predict global warming are so unsophisticated that they cannot even account for the modest 0.5° C warming that has occurred over the past 100 years. The reasoning is that if they cannot forecast backwards accurately, their ability to project forwards reliably is questionable. “We all believe in the physics of the greenhouse effect,” says Solow, “but to say almost anything about timing, the magnitude of change or its geographic distribution is more than we can do” (qtd. in Linden 68).

Dr. Singer is one of the leading opponents of the ‘excessive’ global warming theory. He asserts that the computer programs that predict global warming are mainly simulations of the atmosphere called “general circulation models.” These models are presently incapable of taking into consideration water vapor feedback, ocean currents, the effect of cloud formations on surface temperatures, and the myriad other natural conditions we are unaware of that influence climate. Therefore, the current models predicting a huge global warming in the next century are not validated by actual observations of global temperatures (20).

In any discussion of global warming effects, “feedbacks” must be considered. Feedbacks are reactions to global warming, such as clouds, that will either speed the process up or slow it down. In a warmer world, more water would evaporate and the weather could become cloudier. More clouds would reflect more sunlight but they would also trap more heat from the earth’s surface because they are made of water vapor, another greenhouse gas (Leggett 30). It is unknown whether clouds would have a net warming or a net cooling effect.

One fascinating aspect of the cloud question: Scientists have discovered that sulfur dioxide, a pollutant from smokestacks that is blamed for acid rain, also causes clouds to form. That might explain why many industrial regions of Earth have not warmed up as much in the past century as the computer climate models say they should have. And it raises the possibility that if the U.S. “scrubs” sulfur from smokestack emissions, the air will be not only cleaner but hotter as well (Kane 27).

Some of the unanswered questions regarding global warming are the most intriguing aspect of the debate. Global climate is the product of interactions among many elements. The largest single factor is the oceans, which have 1,000 times more capacity to store heat than the atmosphere. But climate is also affected by land masses, the biosphere (living things), the atmosphere, clouds, glaciers, the sun, the tilt of the earth, and more (Portney 137).

The ocean not only stores the most heat, it is also the Earth’s largest “carbon sink,” containing 55 times as much carbon as the atmosphere and 20 times more than plants (Nulty 102). In his article, “Global Warming: What We Know,” Peter Nulty writes about “carbon sinks,” which are the Earth's natural reservoirs for CO2. He states that plants and trees, for instance, take carbon dioxide from the atmosphere, break it apart, give off the oxygen, and use the carbon to build new cells and grow. When plants die and decay, CO2 is formed and passes into the air or water (103). Fossil fuels like coal and oil constitute a huge store of carbon that was taken out of the cycle millions of years ago when the vegetation that created them became trapped in the earth. There is a finite quantity of carbon on earth which can be recycled through the atmosphere, water, and living things (102).

Man is putting a lot of stored carbon back into circulation by burning fossil fuels. Mr. Nulty points out that one of the more interesting questions regarding carbon dioxide is the “Case of the Missing CO2” (104). Using a rough estimate of how much fossil fuel the modern world has consumed, scientists have calculated how much CO2 has been released into the atmosphere by the process. But when they analyze the atmosphere, they find only half the predicted amount—and they have no idea where the rest went. The only assumption is that the oceans are somehow soaking it up (104).

No one knows how these feedbacks will add up, and that has led to some sharp exchanges between the alarmists and the skeptics among climatologists and scientists. Mr. Nulty states that one prominent skeptic, Richard Lindzen, a professor of meteorology at MIT, recently suggested that in certain areas global warming might decrease the amount of water vapor in the upper atmosphere, which would have a cooling effect. Others argue that water vapor will increase in the lower atmosphere—with the opposite result (105).

Another aspect of global weather which is impossible to project is the part “Mother Nature” plays in the long-range weather patterns. The material available only touches lightly the question of ice ages. Ice ages historically have occurred every 100,000 years and last about 100,000 years, separated by warm periods referred to as “interglacials,” which last about 10,000 years. The earth has experienced about 17 ice age cycles in the last two million years. The last ice age stopped about 10,800 years ago and the warming began (Singer 19). Since the average length of an interglacial is 10,000 years and the present interglacial has been going on for 10,800 years, what does that mean to our planet? Scientists do not know.

There is no reason to believe that the cycles of ice ages will not continue. How man's industrial interference with the climate will affect this cycle is unknown. The global mean temperature at the height of the last ice age was 51 degrees, just eight degrees cooler than today (Singer 20). It occurs to me that if global warming raised our global temperature by seven degrees and a new ice age began which lowered global temperature by eight degrees, would we have saved life as we know it by spewing pollutants into our atmosphere?

Indicative of the entire global warming debate, the consequences of the Mt. Penatubo eruption on world temperature have been analyzed in two separate articles in which the authors have come to diametrically opposed conclusions. In “Brrr! What Global Warming?” (19), mother nature is credited with applying her own highly efficient method of climate control. This Time magazine article reports that the eruption of Mt. Pinatubo put off global warming by five years when it blew its top, shooting 20 million tons of sulphur dioxide into the upper atmosphere. The article further asserts that, since then, the particulates have circled the globe, forming a layer of droplets floating in the stratosphere, which will act as a worldwide sun shield and cool the planet 0.5 degrees centigrade.

Conversely, in “Can We Repair the Air?” (28), Stephen Schneider warns that the 1991 Mt. Penatubo eruption spewed out volcanic emissions that will affect the sunlight falling to earth. He says the bright orange colors on the horizon immediately after sunset are due to the volcanic dust which, in combination with the greenhouse gases, could contribute to increased global warming.

The fact is, science does not yet possess the knowledge to be able to correctly assess the imminence, strength, duration, or after-effects of Mother Nature’s whimsical turns. Humans must accept the fact that there are some cosmic forces beyond our control.

While we must bow to Mother Nature’s inevitable whims, there are many steps we can take to decrease our greenhouse emissions without suffering major economic hardships. Our current energy practices are well behind state-of-the-art technology. Engineering and economic analyses have conclusively demonstrated that cost-effective investments in efficient lighting, housing, machinery, transportation, farming, and other activities can cut emissions in developed countries by about 20 percent before the end of this century at little or no cost (“Conservation” 87).

In fact, as it is pointed out by the USEA in Global Climate Change: An Energy Perspective, increased energy efficiency will not only reduce greenhouse gas emissions that can affect global warming, it will also reduce acid rain, health-damaging air pollutants, dependence on unreliable foreign supplies of energy, and reduce the deficit for energy-importing countries (134). By preserving the Earth’s tropical rain forests we will not only reduce emissions of carbon dioxide, but also protect a vast number of wild species now being driven to extinction through deforestation (161). These are essentially free benefits that we derive from investing in greenhouse gas reductions.

Other benefits would accrue from curtailing population growth, the principal cause of pressure on land, settlements, and natural resources in the developing world. Increasing population pressure and the growing gap in the equitable distribution of resources between developed and developing countries can only make world tensions worse in the 21st century (WCED 186).

While economists agree that energy efficiency is cost-effective, they seem to be more focused on the costs of mitigation. Manne and Richels suggest that major reductions in greenhouse gas emissions will be expensive (73). A recent article in The Economist titled “Our Environment: Whose World is it, Anyway?” maintains that there are limited funds to devote to solving environmental problems and water pollution, soil erosion, loss of species, and deforestation all deserve priority for funding over global warming (26). The article further states that enforceable international agreements are unlikely and reasons that while it would take massive government funds to reduce fossil fuel emissions, costs for adapting to the effects of global warming would more likely be shouldered by the private sector (24).

There are economists such as William Nordhaus of Yale University, however, who feel that it is worth making modest investments today to slow climate change and prepare for its effects. In his article “Turning Up the Heat on the Greenhouse,” Mr. Nordhaus offers suggestions to help mitigate global warming by instituting low-cost energy efficiency measures. He is on the National Academy of Science’s panel for the environment, which also suggests establishing a market in water and reinforcing bridges, buildings, and dams to withstand the effects of global warming (69).

Scientists, engineers, and technologists are divided in their response. They propose that better energy technologies can reduce CO2 emissions in the near-term at lower costs through cost-effective investments in higher energy efficiency and in the longer term through new energy supply technologies and continued application of energy efficiency technology. Specific data in support of the use of better technology to achieve low (or in some cases negative) costs of reducing CO2 emissions are presented in a Appendix F of a report from the U.S. Environmental Protection Agency,“ The Potential Effects Of Global Climate Change on the United States” (144).

Environmentalists are very concerned that this dispute will give policymakers an excuse for inaction, while critics respond that environmental false alarms have historically produced bad policy (Leggett 33). They favor dramatic cuts in fossil fuel consumption in developed countries, preventing developing countries from instituting fossil fuel-based energy sources, dramatically slashing their population growth rates, and stopping massive deforestation (Leggett 32).

While there is no clear cut answer, common sense decrees that it is not healthy to pollute our environment and waste energy. The issues of human-induced climate change must be a global concern from both a scientific and an economic perspective.

Two important changes have occurred in the global climate debate. The first is that the scientific uncertainties of the effect of greenhouse gases on the atmosphere are being more openly acknowledged and the second is that new studies are showing the economic costs of adapting to climate change to be smaller than initially expected (OECD 66). Taken together, it seems prudent for the U.S. to be ready to move aggressively as new information becomes available. At this point it appears inadvisable to pour a trillion dollar solution at what may be a billion dollar problem.

In “Dealing with the Greenhouse Effect,” Stephen Schneider cites that Americans could cut emissions 10-20 percent without even feeling the strain simply by turning out unneeded lights, switching from standard to compact fluorescent or tungsten halogen bulbs; replacing old, leaky windows with heat-mirror windows that hold heat indoors in winter and outdoors in summer; carpooling, walking, riding a bike, or taking public transportation whenever possible; and buying higher miles-per-gallon cars. He maintains that making simple improvements in building insulation, industrial machinery, and public transportation would net another 10 percent and that emissions could be cut another 50 percent by switching from more polluting fossil fuels like coal to natural gas, which contains less carbon, or to solar power and other sources of renewable energy (79).

Developed countries need to increase energy efficiency, decrease waste, and aid developing countries to install non-polluting, energy-efficient power sources. We need an international agreement to stop deforestation and begin reforestation, limit population growth, and establish and enforce global limits on carbon dioxide and other greenhouse gas emissions. Only a coordinated global response will be effective, if a response is proven to be necessary. International cooperation is needed to improve scientific research, to develop technological options, and to develop the financial and institutional mechanisms required to put advanced technology to work effectively.

The international community agrees that the global warming threat is a reality, even if the degree of threat cannot be established. It can only be hopee that the nations of the world can see past their individual borders to respond in a globally responsible way.