Christine, Article...Global Warming....
INTRODUCTION
In the first week of June, an international "Earth summit" will convene to discuss environmental issues and their relationship to economic development. (For an analysis of the circumstances leading up to the conference see Christopher M. Gacek and James Malone, "Guidelines for the U.N. Environmental Conference,"
This summit, formally called the United Nations Conference on Environment and Development, or UNCED, will discuss issues ranging from the distribution of wealth among nations and women's rights to deforestation. But the topic that will attract the most attention and controversy is the claim that the Earth is subject to steady and potentially damaging rise in temperature -- a phenomenon known as "global warming" -- and that this condition is in large part a byproduct of Western industrial growth.
While recent preparatory negotiations did not include binding agreements on targets and timetables for reducing emissions of carbon dioxide (CO2) and other so-called "greenhouse gases," the U.S. will come under enormous pressure at the conference, from other countries and many environmental groups, to sign a treaty curbing greenhouse gas emissions. These greenhouse gases occur in nature but also are caused by human activity, such as by burning fossil fuels. They are responsible for making the earth sufficiently warm to permit the existence of life, and are thus essential. The concern is that the build-up of these gases in the atmosphere could warm the planet more than would otherwise be the case, and that this global warming could lead to adverse changes in the world's ecology. At the extreme, some environmentalists say, parts of the Earth could become subject to flooding and tidal waves because of rising sea levels caused by melting polar ice caps, and drought-induced crop failures could trigger global famine.
In spite of these fears, the accumulated scientific data do not support such dire predictions, showing the cataclysmic results to be either highly improbable or simply wrong. Moreover, there is enormous uncertainty associated with the scientific methodology used to predict future climate changes. Among the difficulties:
Climate change computer models that predict warming often rely on assumptions and simplifications that raise questions about their reliability. Example: one model effectively moved the Earth's orbit 2 million miles closer to the sun.
Models do not accurately account for the influence of important climate factors, such as the behavior and effect of clouds and oceans.
There are shortcomings in the data. Example: temperature records over the last century may incorrectly suggest warming because many weather stations are close to growing cities.
Temperature observations over the last century are inconsistent with the predictions of global warming theories.
A competing theory, based on the hypothesis that solar activity may be the major factor in climate change, is more consistent with temperature observations in the northern hemisphere during the last century.
Furthermore, even if most scientists and policy makers were convinced that some level of warming is occurring and will continue, three questions have to be answered.
Question #1: Is the Earth warming as a result of human-caused greenhouse gases or because of natural phenomena?
Question #2: If the planet is experiencing a major warming trend, in what way will this warming take place? Will the Earth warm up substantially at night with days cooling slightly? Will the warming occur in the tropical regions, or only in the high latitudes around the poles? Will the warming occur in the summer or the winter? These questions are important because a single figure suggesting the average temperature of all regions of the world for all times of day and night during the entire year is a meaningless statistic. It ignores variations amid the warming trend that would have very different -- and not necessarily harmful -- effects in different regions.
Question #3: What will be the effect of any changes in the climate? Will the ocean levels rise, resulting in worldwide flooding? Or will they fall, expanding earth's landmass? Will worldwide agricultural production increase thanks to more crops in areas now too cold for major cultivation -- helping to alleviate world hunger -- or will it decrease, prompting famine in some regions?
The existing scientific evidence does not give clear answers to these questions. But the decisions made by policy makers at the United Nations conference and elsewhere could have enormous implications for the Earth's inhabitants. Moves to slow down economic growth in the western industrialized countries, for instance, could have the unintended effect of slowing economic growth also in the poorest countries. Indeed, poor countries would be disproportionately affected.
The economic costs to Americans from enacting policies to address the perceived problem of global warming would be less dramatic, yet significant. Consider one proposal -- imposing a "carbon tax" of $100 per ton, designed to reduce industry's carbon emissions to the 1990 level by the year 2000. The Congressional Budget Office estimates this tax would reduce the Gross National Product (GNP) of America by two percent. This would result in a loss to the economy of approximately $100 billion per year, or about $1,200 per household. Further, the increase in unemployment would be an estimated 700,000 jobs.
Chart: $100 Carbon Tax Result: Skyrocketing Fuel Prices
Fuel type Cost Increase
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Electricity 27%
Gasoline 27%
Crude Oil 73%
Heating Oil, distillite 33%
Residential Natrual Gas 25%
Wellhead Natural Gas 82%
Utility Coal 165%
Minemouth Coal 240%
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Note: 1989 constant dollars. Base year 1990.
Source: U.S. Department of Energy, Limiting Net Greenhouse Gas Emissions in the United States, 1991.
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To be sure, if the economic, environmental, and health costs associated with global warming are as large as some fear, then the side-effects of reducing CO2 might be smaller compared with the dangers of inaction. This leads to the question asked by many environmentalists and policy makers: "Isn't it worth buying an insurance policy against global warming regardless of cost, since the consequences could be so severe?"
This is a reasonable question, but the answer is not necessarily "Yes." The decision to buy an insurance policy depends not only on the possible consequences of not doing so, but on the probability of those consequences. With a high level of uncertainty, such as that associated with global warming, other measures might be more prudent.
To determine if the world should buy an expensive insurance policy against global warming, the probability of harm occurring must be multiplied by the likely magnitude of the harm. If the resulting expected harm is higher than the economic and social cost, then buying an insurance policy makes sense. If the expected harm is lower than the cost, it does not make sense to do so. Although it is difficult, if not impossible, precisely to quantify the expected harm from global warming, lawmakers must attempt this calculation if they are to develop sensible, cost-effective policies.
WHAT IS GLOBAL WARMING?
One of the main subjects to be addressed at UNCED is global warming. While most Americans have heard of the phenomenon, few understand it, and there is widespread confusion between global warming and another term -- the "greenhouse effect."
The greenhouse effect, on the one hand, refers to the fact that the earth releases gases, called greenhouse gases, which enable the atmosphere to retain some of the heat received from the sun rather than reflecting all of it back out into space. These gases thus have the same effect as glass in a greenhouse, which is to keep the Earth at a higher average temperature, and a more even temperature, than would be the case without the gases. These gases include carbon dioxide, methane, nitrogen oxide, and water vapor. The greenhouse effect maintains the Earth at a temperature which allows plant and animal life to exist. Contrary to popular belief, all scientists agree that the greenhouse effect is desirable. Indeed, without it, life as we know it on Earth would cease because global temperatures would average -18C, or 0F. Explains Patrick Michaels, State Climatologist for the Commonwealth of Virginia, the statement that all scientists agree that the greenhouse effect is real "is about as profound as a statement that all scientists agree that the Earth is round."
Global warming, technically known as the "enhanced greenhouse effect," on the other hand, is a term used to describe temperature increases allegedly caused by humans over some period of time. This theory rests on the claim that certain gases released by human activity warm the planet significantly. These gases include carbon dioxide and other greenhouse gases that are released naturally into the atmosphere. (Water vapor, which is the primary greenhouse gas, is not increased by human activity. Water vapor and clouds account for about 98 percent of the greenhouse effect.) Chlorofluorocarbons (CFCs) are an exception. These are man-made gases, chiefly associated with refrigeration, which do not occur in nature.
THE DEBATE AT UNCED
Many of the delegates at UNCED will demand action to reduce the levels of human-generated greenhouse gases on the grounds that a large rise in the Earth's temperature would be harmful. Among the studies generating these demands is a report to the United Nations Environment Programme (UNEP) by the Intergovernmental Panel on Climate Change (IPCC). ("The Scientific Assessment of Climate Change," The Intergovernmental Panel on Climate Change, August 1990.) This summary concluded that global warming had already occurred, would continue to occur, and was causing a rise in the ocean levels. (The executive summary, however, was not representative of the body of the report, according to 40 percent of the scientists who worked on the document, and was termed "misleading" by half of those scientists. "Survey of U.S. Participants in the IPCC Report," The Science and Environmental Policy Project, August 1991.)
If an agreement to set targets and timetables for reducing man- made greenhouse emissions is reached at the conference, the most popular method to reduce emissions is likely to be a carbon tax. A carbon tax is a tax placed on every ton of carbon dioxide emitted by industry. This would encourage factory owners to reduce CO2 emissions -- which is considered the leading human-caused greenhouse gas.
The U.S. position throughout the discussions leading up to the conference has been that all greenhouse gases should be considered, not just CO2. Only half of the potential warming due to human activity would be caused by CO2, the rest would be due to the other greenhouse gases. The U.S. position has been that the other human-generated greenhouse gases also should be reduced if CO2 is reduced. Putting the burden purely on CO2 disproportionately affects the emerging poor countries and the U.S. economically.
Further, the U.S. has insisted throughout the preparatory negotiations that specific targets and timetable not be included in any treaty. The U.S. position was formally adopted by the International Negotiating Committee (INC). Nevertheless, the negotiated language does state the general proposition that greenhouse gases should be cut.
One of the official concerns has been that the conference will turn into an effort aimed at redistributing the wealth from richer countries, such as the U.S., to poorer nations. Further, the U.S. and other industrialized countries may be pressed to change the foundations of their economic systems and lifestyles to help the less developed countries. Indeed, Maurice Stong, General Secretary of UNCED, claims that industrialized countries have developed and benefitted from unsustainable patterns of production and consumption which have produced the present dilemma, and thus, industrialized countries primarily have the means and responsibility to change these patterns. (Ironically, many environmental ills have not been brought on by industrialized countries. For instance, rainforest destruction is cited as one reason for this conference, but the policies of Brazil, and World Bank programs are largely responsible for the destruction. Brazil requires homesteaders to clear-cut the land in order to gain title. Likewise, the World Bank provided funds to build roads through the jungle to encourage agriculture. Thus, simple policy changes have the potential to curb much of the destruction.)
THE ORIGINS OF GLOBAL WARMING CONCERNS
The theory of global warming was first put forward by Swedish chemist Svante Arrhenius in the late 19th century. Arrhenius theorized that the rise in CO2 emissions caused by increased coal burning during industrialization would warm the Earth considerably. Arrhenius predicted that a doubling of CO2 would increase the temperature by 5C. (Svante Arrhenius, "Philosophical Transactions," 1896. Arrehenius further states that "[t]he influence is in general greater in the winter than in the summer, except in the case of the parts that lie between the maximum and the pole. The influence...is in general somewhat greater for land than ocean. On account of the nebulosity of the southern hemisphere, the effect will be less there than in the northern hemisphere. An increase in [CO2] will of course diminish the difference in temperature between day and night. A very important...secondary effect will probably remove the maximum effect from lower parallels to the neighborhood of the poles.") The enhanced greenhouse effect theory, or global warming, was given new life in the 1950s because the summers were hotter than usual, and was championed by Roger Revelle, then director of Scripps Institution of Oceanography. (Jonathan Laing, "Climate of Fear: The Greenhouse Effect May Be Mostly Hot Air," Barron's, February 27, 1989.)
The Ice Age Theory
The 1960s and 1970s, however, were substantially cooler than previous decades in the northern hemisphere. The global warming theory lost favor and a new theory emerged to supplant it. Many scientists and environmentalists then believed that in fact global warming never had been a real threat and that the concern should be about global cooling. Just as many supporters of the global warming theory argue today, the culprit was said to be human economic activity -- chiefly dust. And just as global warming predictions today are usually stated as fact, so the coming "Ice Age" was presented to the public as fact in the 1960s and 1970s. The only question, according to numerous nationally recognized proponents, was not whether an Ice Age would occur if man continued his destructive activities, but how soon it would come and how devastating the cold would be. (For examples of colorful and forceful quotes by nationally recognized proponents of global cooling, see Anna Bray, "The Ice Age Cometh," Policy Review, No. 58, Fall 1991.)
The Shift Back to Global Warming Theory
The international fear about an apocalyptic Ice Age waned as quickly as it had arisen as soon as the trend of temperatures turned upwards again in the late 1970s. The first computer-simulated climate model to gain attention by suggesting a warming trend, known technically as the General Circulation Model (GCM), was first published in 1975, and revised in 1980. This model predicted that the Earth would warm 4C with a doubling of carbon dioxide (CO2) emissions.
The global warming theory gained enormous support after James Hansen, a physicist and the chief of NASA's Goddard Institute for Space Studies, testified before the U.S. Senate in June 1988 that the full force of human-induced global warming had arrived. (Testimony before the Senate Committee on Energy and Natural Resources, June 23, 1988.) Hansen stated that "global warming is now sufficiently large that we can ascribe with a high degree of confidence a cause and effect relationship to the greenhouse effect." (Ibid.) In support of his conclusions, Hansen declared that 1988 would be the warmest year on record, barring any "remarkable and improbable" cooling. This statement was readily accepted by the press and the general population because the previous winter had been unusually warm and the spring and early summer were much hotter than normal. The remarkable and improbable cooling nevertheless occurred (even as Hansen was testifying) in the tropical Pacific Ocean. A cold front the size of the U.S. Great Plains also settled over Siberia later in the year, bringing average northern hemisphere temperatures downward. In fact, despite the unusual temperatures in the summer of 1988, one out of every six summers since 1895 has been hotter in the U.S., the most recent being 1963. (Jonathan Laing, "For 1989, a Drought Encore?" Barron's, February 27, 1989.)
Since his 1988 testimony, Hansen's vision of global warming has come under increasing attack. (Hansen also testified that the observed warming in the past century was 0.6C to 0.7C. This is 20 to 40 percent higher than any objective trend analysis using the global records considered most reliable. See Michaels, op. cit.) Reid Bryson, a respected expert in climate research and Emeritus Professor of Geography, Meteorology, and Environmental Studies at the University of Wisconsin at Madison, dismissed the Hansen testimony as a "phenomenal snow job" and the global warming theory as "a triumph of sociology over science." (Laing, "Climate of Fear," op. cit.) In fact, the theory that substantial global warming will occur is bitterly disputed by many highly respected scientists. Global warming is not a fact. It is a theory that is widely challenged. In a recent survey of atmospheric physicists and meteorologists, for instance, almost all of the scientists agreed that catastrophic global warming predictions are unsupported by scientific evidence and that climate models showing warming cannot be relied upon. ("Survey of U.S. Participants in the IPCC Report," op. cit.) There are several reason why so many scientists are uncertain about the theory.
Reason #1: The science involved in the global warming theory is very complex.
Scientists generally agree on many of the fundamental concepts behind the greenhouse theory, which is crucial to the catastrophic global warming theory. Where they part company is in making the jump between one theory and the other.
The reason why there can be deep disputes among scientists investigating climate change is that climatology is perhaps one of the most complex and uncertain of all scientific fields. It is not possible to run controlled experiments for the whole planet in a laboratory test tube. Climate conditions cannot be created and changed at will, and then studied. Thus scientists are forced to use models to predict the consequences of various influences, and to try to disentangle the effect of one factor from a myriad of others. Necessarily, such models attempt to include all significant variables and exclude the insignificant ones. The problem is to decide which is which, and if all the variables have in fact been considered.
Given the inherent difficulties in the science of climatology, it is crucial that models are continually tested against data being collected and that scientists accept that conflicts throw their models and theories into question. Unfortunately this does not always happen. For example, Christopher Folland of the United Kingdom Meteorological Office, who was one of the senior authors of the 1990 Intergovernmental Panel on Climate Change report to the U.N. that predicted global warming of 2.5C, recently was asked if the data collected to date (which showed substantially different results from those predicted by models) would alter recommendations for CO2 emission reductions. Folland responded that "the data don't matter," adding that "[w]e're not basing our recommendations on the data; we're basing them upon the GCM [General Circulation Model] climate models." (Presentation by Patrick Michaels at the National Chamber Foundation, U.S. Chamber of Commerce, April 10, 1992.)
Clinging to a model in the face of conflicting data is bad science, and generally leads to bad policy. But the data gathering and modeling problem is made even more difficult because of systematic warming biases of the data on which the models are based.
"Heat Island" Effect. For instance, past observations indicate a global temperature increase of 0.5C over the last 100 years. (It should be noted that almost all of the warming occurred more than 50 years ago, prior to the emission of more than 67 percent of human-generated greenhouse gases. Since 1941, the temperature dropped and then rose about 0.1C.) But questions have arisen over the reliability of even such a basic trend, because recording stations have been placed in areas, such as near cities, that have experienced growing populations over the decades. The buildings and roads which accompany an increasing urban population retain warmth from the sun. This may have exaggerated the long-term temperature rise -- or even suggested one where none exists. This is known as the "heat island" effect.
Extremely accurate and more reliable temperature records do exist -- but only since 1979. Satellite temperature readings, according to Roy Spencer of NASA, and John Christy of the University of Alabama, are accurate within 0.01C, because the satellites use a different method to calculate temperature. Just as important, the satellites are not affected by the heat island effect and the readings cover the entire globe uniformly, unlike ground-based stations which are clustered and sporadic. Significantly, these satellite temperatures show that the ground-based stations records may not be very accurate. The ground-based records show a warming in the southern hemisphere of 0.3C over the past decade, but the highly reliable satellite data contradict this warming trend. In fact, the satellites show that the southern hemisphere temperatures actually dropped 0.02C. This calls into question the wisdom of relying on questionable data accumulated earlier this century as the basis for costly policy changes.
But even if the ground-station records were correct, the results would squarely contradict the global warming theory, which predicts that the northern hemisphere will warm much faster than the southern hemisphere. Northern hemisphere temperatures have not changed significantly. This means that global warming advocates are faced with the prospect of pursuing their theories although the data are suspect and do not support their assertions, or re-examining their theories in light of new satellite data, which show no warming trend where models predicted it should have occurred. Unfortunately they have chosen the first course.
Reason #2: Many models use questionable or incorrect parameters.
Some of the models predicting global warming have been discovered to have included incorrect parameters. Parameters are variables or arbitrary constants in mathematical expressions that generally try to reflect real world conditions which restrict or determine the outcome of the mathematical expression. Sometimes adjusting these parameters can have bizarre results. A prime example is the first influential GCM model, developed in 1975. This model, devised by Sukryo Manabe and Richard Wetherald of the Geophysical Fluid Dynamics Laboratory at the National Oceanic and Atmospheric Administration (NOAA), indicated that the Earth would warm by 4C with a doubling of CO2 in the atmosphere. Unfortunately for the model, it also predicted background temperatures (that is, the temperatures that would occur if there had been no CO2 increase) that would have to be 5C lower than today. It is interesting to note that since the last Ice Age was between 4C and 6C colder than today, an ice age would have occurred if the background model was correct. To correct for this problem, the researchers revised the level of the sun's radiation reaching the Earth's atmosphere upward by 6 percent. But this is equivalent to moving the earth's orbit 2 million miles closer to the sun. (The researchers also used incorrect parameters in another instance in the study. The original study predicted that the polar ice caps would melt at approximately today's temperatures. In the subsequent report, they corrected this error, but left the accelerated warming which is the direct result of ice cap melting in the model.)
A study of Hansen's GCM computer model, which predicts catastrophic warming by the year 2100, found that a one percent difference in the initial conditions or parameters was enough to create totally different predictions of global temperatures over the last half of the period 1991-2100. (A. Tsonis, "Sensitivity of the Global Climate System to Initial Conditions," Eos, No. 30 (July 23, 1991), p. 313.)
Other examples of questionable or incorrect parameters include:
Oceans. The theory that oceans retard the warming caused by greenhouse gases is generally accepted, and incorporated into most newer models. Unfortunately, the magnitude of the ocean effect is poorly understood and roughly estimated. This could introduce significant errors into models. For instance, many researchers claim that it takes 50 years or more for carbon emissions to affect temperatures. Other researchers, however, concluded recently that 75 percent of the full effect of carbon dioxide emissions on sea temperatures is experienced within ten years. (S. Manabe, K. Bryan, and M.J. Spelman, "Transient Response of Global Ocean Atmosphere Model to a Doubling of Atmospheric Carbon Dioxide," Journal of Physical Oceanography, Volume 20 (1990), pp. 722-749.)
Clouds. The problem of determining the effect of clouds is even more complicated, and consequently climate models often contradict each other in the characteristics that they assign to clouds. One theory is that as the temperature increases, because of a rise in greenhouse gases, the relative humidity drops and fewer clouds form. Thus, sunlight reaching the earth increases, causing more warming, or "positive feedback." But another scientific school of thought maintains that clouds have a cooling effect, or "negative feedback." The cloud feedback problem is crucial to a full discussion of the global warming issue, since the models show a range of warming from less than 1C to as much as 5C, depending on the extent and sign (positive or negative) of cloud feedback alone. (George C. Marshall Institute, "Two Environmental Issues" (Washington, D.C. December 1991).)
Recent studies seem to support the view of scientists who theorize a negative feedback from clouds. James Angell, a research meteorologist at the NOAA Air Resources Laboratory, found that between 1950 and 1988, the number of cloudy days increased by 3.5 percent. (J.K. Angell, "Variations and Trends in Tropospheric and Stratospheric Global Temeratures, 1958-1987," Journal of Climate, Vol. 1, No. 12 (December 1988), pp. 1296-1313. The number of cloudy days increased 2 percentage points from approximately 56 percent to 58 percent of total days. This is a 3.5 percent increase in the number of cloudy days.) In addition, other research finds that human-generated sulfates, contributing to atmospheric pollution, also have the effect of enhancing the brightness of clouds. This increases the amount of sun radiation reflected back into space, thus cooling the earth. ("When fossil fuel is burned, both carbon dioxide and sulphur dioxide are added to the atmosphere. The former should cause warming of the lower atmosphere by enhancing the greenhouse effect, whereas the latter, by producing sulphate aerosols, may cause a cooling effect. The possibility that these two processes could offset each other was suggestd many years ago...but during most of the intervening period, attention has focused on the greenhouse effect...Over the next 10-30 years, it is conceivavble that the increased radiative forcing due to SO2 concentration changes could more than offset the reductions in radiative forcing due reduced CO2 emissions." Virginia Climate Advisory, Volume 15, Number 1, Spring 1991, (quoting T.M.L. Wigley, "Could Reducing Fossil-Fuel Emissions CauseGlobal Warming?" Nature, Vol. 349 (1991), pp. 503-505.)
Many scientists have theorized that sulphate aerosols are primarily responsible for the increase in cloud cover, but this theory is challenged by new evidence. In the southern hemisphere, where there are virtually no sulphate aerosols, new evidence shows that cloudiness has increased.
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Michael |
