In 1950, the world’s population was 2.5 billion people. By the year 2050 it is expected to have grown to between nine and ten billion people. During this time of dramatic population growth, the human impact on the planet has increased significantly, not only because of the huge increase in our numbers, but also because of the new technical power to dig deeper, cut faster, build larger, and traverse more quickly great distances in automobiles, trucks, and planes. As a result, serious new environmental problems have emerged on a global scale. These problems include global climate change; worldwide loss of biodiversity, forests, and wetlands; long-range transport of toxic substances; decline of coastal ocean quality; and degradation of the world’s freshwater and ecological systems.1
These new threats raise critical new ethical questions for the human race. Yet even some of the most obvious ethical dimensions of emerging global environmental problems are only dimly seen by most; rarely are they part of the public debate. In a 1999 New York Times op-ed piece on climate change entitled “Indifferent to Planet Pain,” Bill McKibben, wondering why the ethical dimensions of global warming were not more widely understood, writes:
I used to wonder why my parents’ generation had been so blind to the wrongness of segregation; they were people of good conscience, so why had inertia ruled so long? Now I think I understand better. It took the emotional shock of seeing police dogs rip the flesh of protestors for white people to really understand the day-to-day corrosiveness of Jim Crow. We need that same gut understanding of our environmental situation if we are to take the giant steps we must take soon. 2
Yet there is little evidence that global environmental problems feel urgent to most Americans. There are several reasons why this is so.
Unlike the brutal television images of dogs and police attacking defenseless civil rights marchers that galvanized the public in the early 1960s, there is little direct visible evidence that demonstrates how human suffering is being caused in the rest of the world by the profligate use of fossil fuels in the United States. To understand the climate change problem well enough to trigger deep moral concern, one must understand things that are not immediately evident to the naked eye, such as how the burning of fossil fuels in the United States may affect distant people—and an even more distant and abstract posterity. We must learn to see that the amount of coal and oil burning in one country may affect temperatures in many others. We must be able to visualize concretely how the use of certain pesticides in one part of the world is threatening, through long-range air transport, human health and the environment in other places on the globe. We must see that high levels of consumption of paper in the developed world is leading to the destruction of forests in the developing world.
Most ethical systems and our intuitive ethical sensitivity are focused on our responsibilities to people who are close by and can be directly affected by our actions. The technical power that humans now have to affect adversely people they will never meet is a challenge for such ethical systems. Still, global environmental problems raise very serious ethical issues: for example, a global climate change will hurt the poorest on the planet, seriously reduce the quality of life for future generations, and threaten plants and animals around the world. Is this right or just, particularly if those who are most harmed are least responsible for the problem?
Vested interests have in addition often diverted public debate from ethical reflection by focusing on what appear to be “value-neutral” issues of cost-benefit analysis, risk assessment, and scientific uncertainty. The debate appears to revolve around “facts” and thus hides a host of dubious ethical assumptions.
This essay will look at a few emerging environmental problems, such as climate change and diminishing biodiversity, in order to identify some of the more important ethical issues often hidden in the public debate about these matters. As Michael McElroy has pointed out, public analysis of these problems is often limited to scientific and economic concerns. Yet the ethical aspects of environmental problems need to become much more central in public discussions. For one reason, the failure to consider the ethical aspects means that decisions will be made that are inadvertently unjust or unethical; the current generation in the developed world will treat unfairly the interests of future generations and poor people who do not have a say in environmental policy. Second, solutions to our most pressing environmental problems will require concerted action involving almost all of the nations on Earth; most nations are unlikely to agree to such concerted action unless they believe that they are being treated fairly and ethically.
As Michael McElroy has explained, both natural forces and human activities are influencing the global climate. The greenhouse effect, which allows incoming solar radiation to pass through the earth’s atmosphere but prevents much of the outgoing infrared radiation from escaping into outer space, is a natural process. Natural greenhouse gases include water vapor, carbon dioxide, ozone, and other trace gases. Without the greenhouse effect, life on Earth as we know it would not exist.
Emissions of some greenhouse gases are a result of human activities, and these create an enhanced greenhouse effect. These anthropogenic (human-induced) greenhouse gases include carbon dioxide, methane, nitrous oxide, and ozone-depleting substances. Human activities have altered the chemical composition of the atmosphere; as a result, the earth’s climate is changing. Over the past two hundred years, emissions from cars, power plants, and other human inventions have led to about a 30 percent increase in the natural concentration of carbon dioxide and more than a 100 percent increase in the atmospheric concentration of methane. Globally, the average temperature of the earth has warmed over 0.55°C since the mid-nineteenth century, when measurements began.
The Intergovernmental Panel on Climate Change (IPCC), an organization created by the United Nations to study global warming, concluded in a 1995 scientific assessment that “the balance of evidence suggests a discernible human influence on global climate.” In another, more recent assessment, the IPCC has concluded that there is “new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”3 In other words, humans have already begun to change Earth’s climate. It is already too late to prevent some damage to the climate system. Continued addition of greenhouse gases to the atmosphere will further alter the global climate and cause increasing temperatures as well as changes in rainfall and other weather patterns.
The IPCC concluded that unless the world takes steps to reduce emissions of greenhouse gases, global temperatures could rise between 1.4 and 5.80C by 2100.4 Although there are still some scientific uncertainties about the timing, magnitude, and regional impact of such changes, there is strong evidence that they will have significant consequences for humanity and the environment. On the assumption that the climate system responds without sudden nonlinear surprises to greenhouse gas buildup, the projected planetary effects of increased warming include:
- Higher average global precipitation, with some parts of the earth becoming dryer while others become wetter.
- A rise in sea level of 0.09 to 0.88 meters by 2100.
- Changes in regional climate and vegetation.
- Changes in the productivity of agricultural lands.
- Increases in the intensity and severity of tropical storms.5
Models show that the effects of climate change are not distributed equally around the world. Actual temperature differences will likely vary greatly according to location, with projected increases much smaller in the tropics than in regions near the poles. Decreases in precipitation are expected in some areas, while precipitation is expected to increase in others.
Climate models show that the poorest people around the world are the most vulnerable to climate change. This is so for the following reasons:
The ecological systems of many of the poorest nations are most at risk. Human-induced climate change represents an important additional stress to the many ecological and socioeconomic systems already affected by pollution, increasing resource demands, and nonsustainable management practices. The vulnerability of human health and socioeconomic systems—and, to a lesser extent, ecological systems—depends upon economic circumstances and institutional infrastructure. This implies that systems typically are more vulnerable in developing countries where economic and institutional circumstances are less favorable.6
The poorest nations are most vulnerable to storms, flooding, and a rising sea level. Estimates put about 46 million people per year currently at risk of flooding due to storm surges. In the absence of safety measures, and without taking into account anticipated population growth, a 50-centimeter sea-level rise would increase this number to about 92 million; a 1-meter sea-level rise would raise it to about 118 million.7 Studies using a 1-meter projection show a particular risk for small islands and deltas. Some small island nations and other countries will be more vulnerable because their existing sea and coastal defense systems are less well established. Countries with higher population densities will be more vulnerable. Storm surges and flooding could threaten entire cultures. For these countries, a sea-level rise could force an internal or international migration of populations.8
Bangladesh, to take an example, is a densely populated country of about 120 million people located in the complex delta region of the Ganges, Brahmaputra, and Meghna Rivers. About 7 percent of the country’s habitable land (with about 6 million people) is less than 1 meter above sea level, and about 25 percent (with about 30 million people) is below the 3-meter contour.9 Bangladesh is already extremely vulnerable to damage from storm surges. Storm surges in November of 1970 and in April of 1991 are believed to have killed over 250,000 and 100,000 people, respectively. In addition to raising the vulnerability of such regions to catastrophic flooding, climate change increases the threat that tropical storms will be harmful.10
The health of the poor worldwide is at greatest risk from global warming. Climate change is expected to cause significant loss of life in the poorest nations. Direct health effects include increases in cardiorespiratory mortality and illness due to an anticipated increase in some regions in the intensity and duration of heat waves.11 Indirect effects of climate change, which are expected to predominate, include potential increases in the transmission of vector-borne infectious diseases (e.g., malaria, dengue, yellow fever, and some viral encephalitis) resulting from extensions of the geographical range and season for vector organisms.12 Models project that malaria incidence could rise by 50–80 million additional annual cases, relative to an assumed global background total of 500 million cases. Some increases in nonvector-borne infectious diseases—such as salmonellosis, cholera, and giardiasis—also could occur as a result of elevated temperatures and increased flooding. Limited supplies of fresh water and nutritious food, as well as the aggravation of air pollution, will also have human health consequences.13
The food supplies of the poor are especially at risk from global warming. Many of the poorest nations are in arid regions of Africa, Asia, and Central and South America. Relatively small changes in temperature and precipitation, together with the nonlinear effects on evapotranspiration and soil moisture, can result in relatively large changes in runoff, especially in arid and semi-arid regions.14 Many of the world’s poorest people—particularly those living in subtropical and tropical areas and those dependent on isolated agricultural systems in semi-arid and arid regions—are most at risk of increased hunger. Global food supplies during the next century may become increasingly inadequate to meet projected consumption due to both climatic and nonclimatic factors.15
The poorest nations have the least financial and institutional ability to adapt to climate change. The poorest nations are the least prepared to spend money on strategies that might allow them to adjust to hotter and drier climates, more violent storms, rising sea levels, degraded agricultural resources, and increased burdens on human health organizations. Many countries cannot afford food imports, irrigation systems, large-scale public works to prevent flooding, or costly health protection strategies. In the poorest nations, the capacity for research, analysis, and policy development is generally weak. Yet it is precisely the poor who will be most vulnerable to the unanticipated shocks of climate change.
Ethical Issues Raised by Global Warming
There are a number of ethical questions raised by human-induced climate change.
How much degradation from human-induced climate change should be tolerated by the international community? To solve the climate change problem, governments will eventually have to agree at what level to stabilize greenhouse gases in the atmosphere. Under the United Nations Framework Convention on Climate Change (UNFCCC), governments have agreed to take action to stabilize greenhouse gases at a level that “prevents dangerous anthropogenic interference with the climate system.”16 Yet neither the UNFCCC nor subsequent negotiations have been able to agree on a level that is “dangerous.” The level at which greenhouse gases are stabilized will ultimately determine how much damage to human and nonhuman interests is tolerated. For instance, nations could agree to stabilize greenhouse gases at a level that protects human health but allows significant damage to endangered species and ecological systems. Therefore, the decision about the ultimate level of stabilization raises serious ethical questions about what the duties of human beings are to other forms of life, as well as our duties to future generations and to those in poverty, who will suffer the most from human-induced climate change.
At the third Conference of the Parties to the Convention in Kyoto in 1997, the developed nations agreed to reduce greenhouse gas emissions by 5 percent on average below 1990 levels. But this is only a small percentage of what will be needed to stabilize greenhouse gases in the atmosphere. The international community has yet to face the issue of setting an ethically defensible level for these gases.
Is the absence of scientific certainty about the consequences of human-induced climate change a valid excuse for not taking protective action? Those opposing U.S. intervention often argue that no action should be taken on climate change until scientific uncertainties about the impact of climate change are resolved. This American insistence on eliminating uncertainties violates the UNFCCC, a document ratified by the United States, in which the signatories agreed not to use scientific uncertainty as an excuse for not taking action.17 Although there are still some scientific uncertainties about the timing and magnitude of climate change, many facts are not in dispute. We know, for instance, how naturally occurring greenhouse gases warm the planet, how these greenhouse gases absorb infrared radiation, that humans are releasing large amounts of greenhouse gases into the atmosphere, that greenhouse gases are accumulating in the atmosphere in proportion to their human use, and that there has always been a strong correlation in the historical record between levels of greenhouse gases and temperature. The most recent IPCC assessment identifies numerous additional areas where scientific uncertainties have been entirely resolved, or where uncertainties persist but adverse global consequences are highly likely.18 We know that human-induced changes in greenhouse gases in the atmosphere will change the climate in a way that will cause great damage. What we do not know with certainty, given nonlinear feedback mechanisms in the climate system, is the actual timing and magnitude of the change.
This situation poses an important ethical question: is scientific uncertainty about the timing and magnitude of climate change a valid excuse for not taking action? Those who argue that nations have an ethical responsibility to act now can list a number of good reasons for their position:
- The adverse potential impacts on human health and the environment from human-induced climate change are enormous;
- The effects on the poorest people of the world are disproportionate;
- The real potential for very harsh climate surprises is much greater than indicated by the often- quoted predictions that rely on assumptions of linear responses to climate change;
- Much of the science of the climate change problem has never been in dispute;
- Some damage from human activities is likely already taking place;
- The likelihood is strong that serious and irreversible damage will be experienced before all the uncertainties can be eliminated;
- Delay runs risks of its own. The longer nations wait to take action, the more difficult it will be to stabilize greenhouse gases at levels that do not create enormous damage.
Should cost-benefit analysis of climate-change programs be used as a prescriptive tool for national policy? Some in the United States who oppose government action on climate change argue that action is not justified because the costs to the United States of reducing greenhouse gas emissions outweigh the benefits to the United States of preventing global warming. This use of cost-benefit analysis as a prescriptive tool raises several ethical issues, most of which are hidden in public-policy debates. The questions raised by a cost-benefit analysis include:
- Whether costs to the United States alone can justify lack of action by the United States to reduce greenhouse gases, which could cause harm in other nations;
- Whether an analysis that relies on a market-based “willingness-to-pay” method of determining the value of damages to plants, animals, ecosystems, or humans distorts other ways of valuing nature;
- Whether a mode of analysis that omits questions of distributive justice or duties to future generations is ethically defensible.
Do the developed nations have special responsibilities to act before the poorer nations? Another standard objection to American action on climate change is the argument that the United States should take no action until the developing world agrees to reduce greenhouse gas emissions. This argument rests on the fact that the United States cannot solve the problem of climate change by itself, and some nations in the developing world continue to contribute to the problem. If the United States acts and the developing world does not, so goes this argument, climate change will still happen and American industry will put itself at a competitive disadvantage. For this reason, there has been strong opposition to the Kyoto Protocol provisionally signed by the Clinton administration in December of 1997. In response, the Clinton administration announced it would not seek Senate ratification of the Kyoto Protocol until it obtained firmer commitments to reduce emissions from the developing world. In the meantime, the U.S. Congress would not approve any government action to reduce greenhouse gases, arguing that such action would amount to a back-door ratification of Kyoto. Although the George W. Bush administration has recently announced that it will reject the Kyoto Protocol, on several occasions it has stated that developing-world commitments will be a cornerstone of its approach to an international regime created to reduce greenhouse gas emissions.
Yet the United States emits a disproportionate share of greenhouse gases. With 4 to 5 percent of the world’s population, it emits 22 percent of the world’s greenhouse gases. The United States has also contributed mightily to the magnitude of the existing problem. Given the historical contributions of developed nations like the United States and the current imbalance in per capita emissions, those who argue for immediate action by the developed nations make their argument on grounds of equity. They argue that those who have caused most of the existing problem and have the resources to finance reduction strategies have a special duty to reduce emissions immediately.
Is it legitimate for any nation to refuse to take action until all nations agree on “least-cost” solutions? The third argument against the United States’ taking immediate action is based on the idea that the United States has a right to insist upon an international regime that will reduce U.S. costs. Many have argued that the United States should not unilaterally reduce greenhouse gases until the details of a worldwide system for trading carbon are agreed to. At the UNFCCC in Kyoto, the United States successfully promoted various market-based mechanisms to trade property rights in carbon reductions. Although the general framework of these trading mechanisms was agreed to in Kyoto in 1997, many of the details are still contentious. Yet the United States insists on waiting until an international trading regime is in place before taking domestic action. To establish such a regime, a large number of complex issues will need to be worked out:
- How to develop an international baseline for carbon sources;
- How to avoid cheating from projects that do not actually reduce greenhouse gases;
- How to keep track of whether carbon reductions have occurred;
- How to avoid giving credit for improvement that would happen without climate change programs;
- How to measure credit for carbon sequestration projects in forests and agriculture when it is not clear what carbon reductions will permanently be achieved from such projects;
- How to decide if a rich country like the United States should be allowed to achieve all of its legally required reductions by buying credits from poor nations that will sell them.
Because of the complexities entailed by any scheme to implement a trading regime, insisting that all the details be worked out in advance could delay for years any agreement on reductions. Given that the United States is currently the nation emitting the most greenhouse gases, it is ethically dubious for it to make universal agreement on trading rules a precondition for American action to reduce emissions. One of the most important ethical issues entailed by the trading controversy, therefore, is whether a nation that is emitting large amounts of a pollutant that is likely to cause great damage can use as a valid excuse for not taking action the fact that other nations will not agree to a trading regime that might reduce costs.
There are, finally, several other ethical issues raised by the American approach to establishing a trading regime. They include questions of whether the atmosphere’s capacity to absorb safely some amount of greenhouse gases should be divided up into property rights that can be brought and sold, and whether a trading regime based upon an inequitable allocation among nations is just.
What national targets for reducing greenhouse gases are equitable? In addition to the dubiousness of allowing efficiency to trump ethical concerns, the trading regime suffers from another potentially serious ethical problem: it can only be ethically benign if the preliminary allocation is just.19 Before trading can take place, nations must agree on a fair allocation of emissions allowances that will become the baseline of the system. Because the United States has between 4 and 5 percent of the world’s population but emits 22 percent of the greenhouse gases, its final share of allowable emissions ought to take into consideration its disproportionate responsibility for the problem.
In Kyoto in 1997, the United States agreed to a 7-percent reduction below 1990 levels. This was a first step toward reducing greenhouse gases, but only a small step: far greater levels of reduction will be needed to stabilize greenhouse gases in the atmosphere at safe levels. To achieve that goal, all the world’s nations will need to reduce emissions by 50 to 80 percent below the level of emissions in 1990. Given the variations in historical and cumulative emissions, current total and per capita emissions, and factors such as wealth, energy structures, and resource endowment, what are equitable national caps for greenhouse gas emissions? Some developing nations have argued that distributive justice demands that national allocations be based on a per capita calculation. The United States has resisted discussions of an equitable basis for determining national responsibilities, despite the fact that in ratifying the UNFCCC the United States agreed that each nation should reduce its emissions according to equitable criteria.20
LOSS OF BIODIVERSITY
Another global threat is the worldwide loss of biodiversity, a term that describes nature’s variety. Biodiversity is usually analyzed at three different levels: genetic diversity, species diversity, and ecosystem diversity.21
Although species extinction has existed since life first emerged on Earth, worldwide concern about rapid loss of biodiversity has been steadily increasing. Current rates of extinction are probably much greater than they have been at any time in history, except at periods of cataclysmic destruction. Rates of species extinction have increased dramatically as human numbers and technological power have increased.
The actual rates of species extinction are not known, because relatively few species have been identified. Although scientists have been cataloging species for over two centuries, only 1.8 million have been identified out of a total 3 to 30 million estimated species worldwide. While a great deal is known about higher-level species, such as mammals, birds, and some plants, less is known about insects and microorganisms. Because so many species have not been identified, scientists worry that many will become extinct before they are ever discovered and properly cataloged.
Given known rates of extinction, it is clear that humans are accelerating these rates as their impact on the planet increases. Scientists can account for the extinction worldwide of 75 mammals and over 1,600 birds, resulting in a loss rate of one species every four years up until the end of the nineteenth century. Between 1900 and 1980 another 75 mammals and birds became extinct, and the loss rate accelerated to one species a year. In 1993, the estimates for mammal and bird extinction were between one and three species a year.
Although mammals and birds receive most of the public’s attention, lower species such as insects often play a vital role in the web of life. The most optimistic scientific estimates suggest that depletion rates for all species currently run from one to three species a day. Some of these projected losses are to species such as pollinating insects that may play important roles in maintaining ecosystems.
Scientists estimate species loss rates by making projections from known rates of habitat loss and comparing these with known species losses in similar ecosystems that have lost habitat. Based on these projections, a recent United Nations report projects that between 2 and 25 percent of the world’s tropical forest species will become extinct in the next 25 years.
Worldwide, the major threats to biodiversity are nonnative species introduction, habitat destruction, and hunting or other acts of deliberate extermination. Habitat destruction is caused by land development, by degradation caused by pollution or vegetative removal and erosion, and by fragmentation of ecosystems.
The Ethical Problems Entailed in Protecting Biodiversity
We have a duty to protect biodiversity. Loss of biodiversity raises the ethical question of human responsibility to protect plants and animals. Utilitarian, deontological, biocentric, ecocentric, and feminist ethical ways of thinking about biodiversity loss may lead to different conclusions about duties to preserve plants, animals, and ecosystems. Some argue that the duty to protect plants and animals stems from their value for human uses; those who base the value of plants and animals on human use often attempt to quantify that value by measuring their potential market value in the form of food, pharmaceuticals, fibers, and petroleum substitutes. Yet others argue that plants and animals have intrinsic value and should be treated as sacred objects rather than as material for human consumption. If biodiversity has a value that cannot be quantified in market transactions, it should not be treated as a commodity in a cost-benefit analysis.
Who should payfor protection of biodiversity? The greatest losses of biodiversity are occurring in species-rich tropical areas and in other places inhabited by many of the world’s poorest peoples. In many places, poor people threaten biodiversity by clearing forests to grow food. As a result, if richer nations do not assist the poorer nations, a great degree of the world’s biodiversity will be lost. Moreover, other species-rich areas in poorer nations are threatened by activities such as logging. In order to relieve grinding poverty, poorer nations have been encouraged by richer nations to exploit natural resources for export. For this reason there is an indirect causal link between the use of resources in the developed world and their exploitation in the developing world. Although the richer nations have provided limited funds to protect biodiversity in poorer nations, the richer nations often deny that they have any special responsibility to protect biodiversity. Many international meetings on biodiversity have been marked by bitter disagreement between rich and poor nations about who should pay for this protection.
OTHER EMERGING GLOBAL ENVIRONMENTAL PROBLEMS
There are several other serious global environmental problems:
- Worldwide evidence is growing of threats to ecosystems and human health caused by long-range air pollution. There is particular concern about a class of chemicals generally referred to as persistent organic pollutants (POPs). POPs are receiving international attention because they are toxic to humans and animals, do not degrade readily in the environment, tend to bioaccumulate, and often change from a solid to gaseous phase and thereby travel long distances in the air before being redeposited in the environment. Scientific evidence is mounting that some POPs cause a variety of genetic, reproductive, and behavioral abnormalities in wildlife and humans, and may be associated with increased incidence in humans of cancer and neurological deficits.22
- Marine ecosystems in coastal areas around the world are being seriously threatened by urbanization and the aquatic pollution it creates. Recent losses of coral reefs around the world are of particular concern. Humans are also endangering marine food supplies by overexploiting fish stocks.23
- The world’s fresh water supply is under great threat from overuse, expanding populations, and pollution. Almost a billion people do not have adequate drinking water, and diminishing fresh water supplies especially threaten poor people who are trying to grow crops on arid land.24
- About 40 to 50 percent of the land on Earth has been irreversibly transformed (through change in land cover) or degraded by human action.25
- Natural forests continue to disappear at a rate of 14 million hectares per year.26
These environmental problems, like the problems of human-induced climate change and loss of biodiversity, raise the ethical question of our human duty to protect animals and plants from destruction by human behavior and of the responsibilities of the developed world to the developing world. The use of organic chemicals in any nation can cause damage elsewhere. Both ocean and fresh-water degradation are being caused in part by a climate change that is largely caused by the developed nations. For these and several other environmental problems, there is a direct causal link between activity in the developed world and damage in the developing world. For other problems, the causal connection is indirect. For instance, some of the damage to coastal areas and water supplies in the developing world is being caused by manufacturing and resource extraction in poorer nations to meet high levels of consumption in richer nations. Moreover, the costs of mitigating toxic, ocean, and fresh-water problems is much more onerous for developing nations. Progress on solving these problems depends on deciding who should pay for the protection of global environmental resources—and this is an issue of distributive justice.
Given the obviousness of some of the ethical questions raised by global environmental problems, the failure to address these questions seems odd. One reason is that vested interests have consciously attempted to “reposition” the issues so that apparently “value-neutral” issues supplant ethical debate. Concerned persons should resist this marginalization of moral issues. Most recently, disputes about international distributive justice have become the largest blocks to international negotiations on global environmental issues; for instance, at the five-year review of the Rio de Janeiro Earth Summit, bitter fights between rich and poor nations blocked progress on moving the international environmental agenda. If we are going to prevent serious global environmental damage, concerned people must speak out about the value of nature, and also the value of international distributive justice.
1 This paragraph and several others in this essay are rewrites of material written by the author in Emerging Global Environmental Issues, United States Environmental Protection Agency, January 1997, Document 160–K–97–001.
2 Bill McKibben, New York Times, 4 September 1999.
3 Intergovernmental Panel on Climate Change (IPCC), Working Group II, Summary for Policymakers, Climate Change 2001: Impacts, Adaptation, and Vulnerability, Third Assessment Report, February 200 http://www.usgcrp.gov/ipcc/wg2spm.pdf.
7 Intergovernmental Panel on Climate Change (IPCC), IPCC Second Assessment Synthesis of Scientific-Technical Information relevant to interpreting Article 2 of the UN Framework Convention on Climate Change, http://www.ipcc.ch/pub/sarsyn.htm.
9 John Houghton, Global Warming, The Complete Briefing (Cambridge: Cambridge University Press, 1997 ), 111.
11 IPCC, Working Group I (Science), Summary for Policymakers.
17 Ibid., Article 3.
18 IPCC, Working Group II, Summary for Policymakers, Climate Change 2001; IPCC, Working Group I (Science), Summary for Policymakers.
19 Mark Sagoff, “Controlling Global Climate: The Debate Over Pollution Trading,” Report from the Institute for Philosophy & Public Policy 19 (1) (Winter 1999).
20 UNFCCC, Article 3.
21 Brown, Emerging Global Environmental Issues.
25 Edward Ayensu et al., “International Ecosystem Assessment,” Science 286 (5440) (22 October 1999): 685–686.