CHAPTER 3
GLOBAL CLIMATE CHANGE

Although large changes in climate are a natural part of Earth history, there is little doubt that human activities have caused observed patterns of global warming in the twentieth and twenty-first centuries. Global climate change has large implications for both humans and wildlife. Many threatened and endangered species, which already lead a precarious existence, are likely to suffer further declines. Global warming also threatens populations of species that were once relatively secure, and is likely to result in the endangerment of more species in the future.

A study of habitats comprising 20 percent of the earth's surface suggested that 15 to 37 percent of the world's species may be extinct by 2050 if recent warming trends continue ("Extinction Risk from Climate Change," Nature, no. 427, January 2004.) Summarizing his findings, ecologist Chris D. Thomas said, "The midrange estimate is that 24 percent of plants and animals will be committed to extinction by 2050. We're not talking about the occasional extinction—we're talking about 1.25 million species. It's a massive number."

CLIMATE CHANGE IN EARTH HISTORY

Over hundreds of millions of years, geological and astronomical forces have changed Earth's environment from hot to cold, wet to dry, and back again. Studies have shown that the climate has fluctuated between long periods of cold lasting 50,000 to 80,000 years and shorter periods of warmth lasting about 10,000 years. The Earth is in the midst of one of those warm periods now. These climate cycles are caused by tiny irregularities (known as Milankovitch Cycles) in the Earth's orbit around the sun. The climate of the past 10,000 years, during which human civilization developed, is a mere blip in a much larger history of climate change. However, human influences on the climate are significant, and effects are already being seen on species worldwide.

GLOBAL WARMING—THE RESULT OF HUMAN ACTIVITY

The Greenhouse Effect

Earth's climate is a delicate balance of energy input, chemical and biological processes, and physical phenomena. The Earth's atmosphere plays a critical role in planetary surface temperature. Some gases, such as carbon dioxide (CO2) and methane (CH4), absorb and maintain heat in the same way that glass traps heat in a greenhouse. These greenhouse gases in Earth's atmosphere allow temperatures to build up, keeping the planet warm and habitable to the life forms that have evolved here. This phenomenon is called the greenhouse effect. Figure 3.1 shows how the greenhouse effect causes elevation of surface temperatures on Earth.

The "natural greenhouse effect" creates a climate in which life can exist. It maintains the mean temperature of Earth's surface at approximately 33 degrees warmer than if natural greenhouse gases were not present. Without this process, Earth would be frigid and uninhabitable. However, an "enhanced greenhouse effect," sometimes called the "anthropogenic effect," refers to the increase in Earth's surface temperature due to human activity.

A Revolutionary Idea

Earth's atmosphere was compared to a glass vessel in 1827 by the French mathematician Jean-Baptiste Fourier. In the 1850s British physicist John Tyndall measured the heat-trapping properties of various components of the atmosphere. By the 1890s scientists had concluded that the great increase in combustion in the Industrial Revolution had the potential to change the atmosphere's load of carbon dioxide. In 1896 the Swedish chemist Svante Arrhenius made the revolutionary suggestion that the rapid increase in coal use during the Industrial Revolution could increase carbon dioxide concentrations and cause a gradual rise in temperatures. For almost six decades, his theory stirred little interest.

Then in 1957 studies at the Scripps Institute of Oceanography in California showed that, in fact, half the carbon dioxide released by industry remained permanently trapped in the atmosphere. Atmospheric concentrations of carbon dioxide were shown to be at their highest level in 160,000 years.

More recent studies have provided evidence that levels of other greenhouse gases are also rising due to human activity:

• Methane (CH4). Its atmospheric concentration is now about 150 times higher than in the pre-industrial era. Some estimates indicate that methane's concentration in the atmosphere could double again during the next 100 years.
• Nitrous oxide (N2O). This gas comes from fertilizers used in agriculture, combustion of fossil fuels and solid waste, and industrial processes. Scientists estimate that there is 16 percent more nitrous oxide in the atmosphere presently than there was in 1750.

Man-made greenhouse gases, particularly fluorinated compounds, also contribute to global warming. These include:

• Chlorofluorocarbons (CFCs). The Montreal Protocol on Substances That Deplete the Ozone Layer phased out, with a few exceptions, the use of these popular aerosols, refrigerants, and solvents.
• Hydrochlorofluorocarbons (HCFCs). Designed as substitutes for the ozone-depleting CFCs, they have about one-fifth the stratospheric ozone depletion potential of CFCs and most of the same uses.
• Hydrofluorocarbons (HFCs). These low-cost and often energy-efficient compounds are used in insulation, air conditioning, refrigeration, fire suppression, and medical metered dose inhalers.

Most man-made gases are present in the atmosphere now at concentrations about 25 percent greater than 150 years ago. The Intergovernmental Panel on Climate Change (IPCC) has documented increases in the levels of a number of greenhouse gases. The panel has conducted studies of ice cores obtained from Antarctica and Greenland—as ice gradually accumulates over millenia, it traps tiny air bubbles that yield information on past atmospheric conditions. Some of the ice cores examined required drilling to depths of thousands of feet.

Earth's Increasing Temperature

As of 2004 experts are almost certain that human-induced climate change is occurring due to increased levels of greenhouse gases. The IPCC, sponsored jointly by the United Nations Environmental Programme (UNEP) and the World Meteorological Organization, was formed to study climate change and to advise policymakers worldwide.

Evidence that global temperatures have been increasing comes from sources as diverse as fossils, corals, ancient ice, and growth rings in trees. The IPCC published a report in 2001 that shows global surface temperatures as measured by thermometers in the last 140 years. A marked rise of approximately one degree has occurred during the 140-year time course. There are extremely striking increases documented in the twentieth century. Data used to document these increases are derived from tree rings, corals, ice cores, and historical temperature records. Climate models suggest that the Earth will warm another two to six degrees between 2000 and 2100. If this happens, it will be the warmest Earth has been for millions of years.

Greenhouse Gases and Emission Trends

Total greenhouse gas emissions from 1991–2001 are shown in Figure 3.2. Emissions increased sharply through the 1990s, but dropped between 2000 and 2001. This drop is attributed to slow economic growth in the U.S. that year, as well as to reduced heating demands due to an unusually warm winter in 2001.

Although carbon dioxide is the primary driver of global warming, several other gases also impact temperatures significantly. Figure 3.3 shows U.S. greenhouse gas emission by type of gas in 2002.

CARBON DIOXIDE.

Carbon dioxide, a naturally occurring component of Earth's atmosphere, is generally considered the major cause of global warming. Carbon is an essential component of all living organisms. The carbon cycle, which shows the movement of carbon from organic to inorganic forms, is illustrated in Figure 3.4. Plants perform the essential function of taking carbon dioxide from the atmosphere and converting it to organic matter, a form that can be used by other living species.

The Energy Information Administration of the U.S. Department of Energy reported in 2002 that carbon dioxide accounted for 82.8 percent of greenhouse gas emissions in the United States (shown in Figure 3.3). The burning of fossil fuels by industry and motor vehicles is by far the leading source of carbon dioxide, accounting for more than 96 percent of carbon dioxide emissions. (See Table 3.1 and Figure 3.5.) As populations and economies expand, they use ever-greater amounts of fossil fuels. Consequently, most carbon dioxide emission comes from the developed world.

Contributions from the developing world are expected to increase as these countries industrialize. (See Figure 3.6 and Figure 3.7.) The United States, despite having only 5 percent of the world's population, accounts for 25 percent of the world's energy use, making it the most carbon-intensive country on Earth. Figure 3.8 and Figure 3.9 document the sources of energy in the United States—the bulk is derived from fossil fuels (petroleum, natural gas, and coal).

METHANE.

Methane is second only to carbon dioxide in its contribution to global warming, contributing 8.9 percent of greenhouse gases in 2002 (shown in Figure 3.3). While there is less methane than carbon dioxide in the atmosphere, scientists estimate that it may be 21 times more effective at trapping heat. Since the 1800s, the amount of methane in the atmosphere has more than doubled. Scientists attribute this rise to human sources, including landfills, natural gas systems, agricultural activities, coal mining, and wastewater treatment. Sources of methane in 2001 are shown in Figure 3.10.

NITROUS OXIDE.

Nitrous oxide is a greenhouse gas with natural biological sources as well as human sources. Although nitrous oxide makes up a much smaller portion of greenhouse gases than carbon dioxide (4.9 percent in 2002), it is as much as 310 times more powerful than carbon dioxide at trapping heat.

CHLOROFLUOROCARBONS.

Chlorofluorocarbons (CFCs), an important class of modern industrial chemicals, caused some of the anthropogenic greenhouse effect and global warming experienced during the 1980s. CFCs are also responsible for depletion of the ozone layer in the stratosphere, which has resulted in increased levels of damaging ultraviolet radiation on Earth. The United States is the leading producer of CFCs. Beginning in the 1970s the United States and some other nations banned the use of CFCs in aerosol sprays. In 1987 leaders of many world nations met in Montreal, Canada, and agreed to cut CFC output by 50 percent by the year 2000. In 1989, 82 nations signed the Helsinki Declaration, pledging to completely phase out five CFCs.

Forests and Oceans as Carbon Sinks

Because plants naturally take in carbon dioxide from the atmosphere for photosynthesis, large forests act as sinks, or repositories, for carbon. There has been some debate about whether forests are capable of soaking up the excess carbon dioxide emitted through human activity. Some scientists have also argued that the increasing levels of carbon dioxide in the atmosphere might be better tolerated if not for the additional complicating factor of global deforestation. (See Figure 3.11.)

Oceans may also have a profound effect on climate change, both because of their tremendous heat storage capability and because they affect levels of atmospheric gases. The ocean is by far the largest reservoir of carbon in the carbon cycle. It holds approximately 50 times more carbon than the atmosphere and 20 times more than the terrestrial reservoir. Ocean currents also transport stored heat, causing heating and cooling in different parts of the world. It is still unclear, however, what effects oceans may have on global warming.

Other Factors Affecting the Global Climate

VOLCANOES.

Volcanic activity, such as the 1991 eruption of Mount Pinatubo in the Philippines, can temporarily offset global warming. Volcanoes spew vast quantities of particles and gas into the atmosphere. Sulfur dioxide, a frequent product of eruptions, combines with water to form tiny super-cooled sulfuric acid droplets. These create a long-lasting global haze that reflects sunlight, reducing the amount of heat absorbed and cooling the planet. (See Figure 3.12.) The effects of the Mount Pinatubo cloud—the largest volcanic cloud of the twentieth century—were felt for years. It not only blocked a significant portion of the impinging sunlight but affected wind and weather patterns. Weather anomalies such as cooler summers and warmer winters, as well as an overall cooling effect, were observed for several years. Similarly, the explosion of the El Chichon volcano in Mexico in 1982 depressed global temperatures for about four years.

CLOUDS.

Clouds also contribute to global climate patterns. Clouds can either reflect sunlight, cooling the Earth, or cause the planet to retain heat. These differing effects depend largely on the brightness and thickness of the clouds in question. Marine stratocumulus clouds, which occur at low altitudes over the ocean, are known to reflect solar energy, resulting in a cooling of the Earth. (See Figure 3.13.) Other clouds, however, such as the cirrus clouds that occur at high altitudes, enhance global warming. A

2000 study at NASA's Goddard Institute for Space Studies reported that global warming results in the formation of thinner clouds that are less capable of reflecting sunlight.

SOLAR CYCLES.

Finally, the sun itself is not an entirely steady source of energy. The sun has seasons, storms, and characteristic patterns of activity. Sunspots and flares appear in cycles of roughly eleven years, and may well contribute to climate change on Earth. Future studies of each stage of this cycle are expected to produce a wealth of new data that will increase our understanding of these phenomena.

EFFECTS OF A WARMING CLIMATE

In 1990 the Intergovernmental Panel on Climate Change (IPCC) noted several early signs of climate change in Earth's colder habitats. The average warm-season temperature in Alaska had increased three degrees in fifty years. Glaciers had receded and thinned by thirty feet in forty years. There was significantly less sea ice in the Bering Sea than in the 1950s. Permafrost had thawed, causing landslides, erosion, and local floods. Ice cellars in northern villages thawed, becoming useless. More precipitation fell as rain than snow, and snow melted faster, causing more running and standing water.

Since then, further evidence of global warming has been frequent and diverse:

• Heat waves and unusually warm weather have been reported at numerous locales, resulting in increased levels of human heat-related illness and death.
• Sea level rise, resulting from the expansion of warmer sea water and the melting of glaciers, is estimated at four to ten inches over the course of the twentieth century. Sea level rise has resulted in land inundation, coastal flooding, and erosion.
• Incidents of heavy snowstorms and rainfall have increased.
• Droughts have increased in frequency.
• Mountain glaciers have continued to shrink, and have disappeared in lower latitudes.
• Diseases formerly confined to tropical regions, including several mosquito-borne diseases, have increased their range to higher altitudes and latitudes.
• Spring arrives earlier in many places.
• Numerous biological species have shifted their ranges to occupy higher latitudes and higher elevations.

In March 2002, in what is perhaps the most dramatic event resulting from global warming to date, the giant Larsen B ice shelf collapsed off the coast of Antarctica. (See Figure 3.14.) Ice shelves are thick blocks of ice that are continuations of the ice sheets that cover the Antarctic continent. The Larsen B shelf was larger than the state of Rhode Island and likely had existed since the end of the last ice age 12,000 years ago.

Global temperatures are predicted to continue to rise. Some of the major effects of global climate change, and the likelihood of their occurrence, were listed by the IPCC in 2001. Many of these predictions have drastic consequences for humans as well as for wildlife.

Global Warming and Human Health

Higher temperatures alone are killing some people, particularly young and old people in urban areas. Over 250 died during a heat wave across the eastern United States in the summer of 1999. Most of these heat-related deaths occur directly from heat-induced strokes and heart attacks.

Air quality also deteriorates as temperatures rise. Hot, stagnant air contributes to the formation of atmospheric ozone, the main component of smog. Poor air quality also aggravates asthma and other respiratory diseases.

Higher temperatures and increased rainfall could create ideal conditions for the spread of a host of infectious diseases by insects, including mosquito-borne malaria, dengue fever, and encephalitis. Some tropical diseases have already spread beyond their old ranges, affecting people at higher altitudes and latitudes. For example, dengue fever, once restricted to altitudes below 3,300 feet, was reported at altitudes above 4,000 feet in Central America in 1999, at 5,600 feet in Mexico in 1998, and at 7,200 feet in the Andes Mountains of Columbia in 1998. Similarly, malaria was detected at high altitudes in Indonesia in 1997. Expansion of malarial ranges have also been reported in parts of Africa. West Nile virus-induced encephalitis, which is native to Egypt and Uganda, was first seen in the United States in 1999; by 2003 it had spread throughout the continental U.S., except for Oregon.

Sea Levels and Precipitation Patterns

The National Climatic Data Center reports that sea levels rose by as much as 10 inches in the twentieth century. The Climate Institute in Washington, D.C., forecasts a further rise of 8 inches by 2030 and 26 inches by 2100 if current trends continue. These would be caused by the expansion of seawater as it is warmed, as well as by melting glaciers and ice caps.

Rising sea levels would narrow or destroy beaches, flood wetland areas, and either submerge or require the costly fortification of shoreline property. Numerous coastal cities worldwide would be flooded. Rising waters would also intrude on inland rivers, destroying freshwater habitats, threatening human water supplies, and increasing the salt content of groundwater.

A warmer climate is also likely to shift the rain belt of the middle latitudes toward the poles, affecting rainfall patterns around the world. Wetter, more violent weather is projected for some regions. The opposite problem—too little water—could worsen in arid areas such as the Middle East and parts of Africa. Frequent droughts could plague North America and Asia as well. Some experts have suggested that "global warming" is too mild a term for an era marked by heat waves that will make certain regions virtually uninhabitable.

Decreasing Biological Diversity

Global biodiversity is also predicted to suffer from planetary warming. Certain ecosystems will shrink or be lost entirely, including cold-temperature habitats such as tundra, and specialized habitats such as coral reefs and coastal mangrove swamps. Other species expected to be heavily affected include those that require habitat within narrow bands of temperature and humidity, such as the monarch butterfly or the edelweiss flower.

Many ecosystems are expected to shift geographically toward more appropriate climate regimes. However, some species may be unable to migrate rapidly enough to cope with climate change at the projected rates. Species expected to be most successful, in fact, include opportunistic varieties such as weeds and pests. The EPA warned in 1988, "If current trends continue, it is likely that climate may change too quickly for many natural systems to adapt."

SPECIES RANGE SHIFTS.

The ranges of most species depend, among other things, on temperature and climate. A number of plant and animal species have already shifted their geographic ranges in response to warming patterns. Range shifts have been reported in alpine plants, butterflies, birds, invertebrates, and mosquitoes.

A 1999 study by Dr. Camille Parmesan and colleagues showed that among surveyed European butterfly species, 63 percent had shifted their ranges northward. Moreover, these species had shifted their ranges by a distance corresponding to temperature rises on the European continent. Dr. Parmesan also showed that one California species, Edith's checkerspot butterfly, has been disappearing from the southern parts of its range, as well as from lower-elevation habitats. Similarly, a 1999 study of bird species in the United Kingdom revealed that ranges have shifted north by an average of 12 miles. In the Olympic Mountains in the state of Washington, biologists reported in 1994 that sub-alpine forests have shifted to higher elevations previously characterized by alpine meadows. In Monterey Bay, California, a 1995 study showed that invertebrate species such as snails and starfish have shifted north as well. In Germany, a study of mollusk species showed that 20 percent of species had shifted their ranges. Range shifts of mosquitoes are supported by the occurrence of mosquito-borne diseases such as dengue fever at more northern latitudes and at higher altitudes.

DISAPPEARING SPECIES.

Some species will be unable to shift their ranges in response to global warming. There may be physical barriers that are difficult or impossible to cross—mountains, perhaps, or oceans or other bodies of water. The species they depend on for food or other resources may not have shifted their ranges. Or, species may encounter new competitors or predators as they try to move into new habitats. These species are likely to decline with global warming.

Population declines have recently been reported in a number of habitats and species. Mangrove forests have been inundated by water due to rising sea levels and are dying. Arctic species are particularly vulnerable. An Arctic bird species, the black guillemot, is declining because of reductions in the amount of floating sea ice—ice formed by frozen saltwater. This has resulted in decreased food availability for guillemots as well as a reduction in the number of available nesting sites. Adelie penguin populations have declined dramatically in Antarctica, probably because of a reduction in sea ice, which not only provides penguin habitat but is essential to the penguins' primary food source, krill. In the Monteverde cloud forest of Costa Rica, where a unique, moist habitat is created by large amounts of water mist, an altitudinal rise in the cloud bank has resulted in the extinction of some twenty frog species as of 1999. Declines in lizard populations have also been documented, as well as altitudinal shifts by populations of birds and bats.

An issue of particular concern is the loss of plant species due to global warming. Plants are often less able to shift their ranges than are animals, which are mobile. As plants form the basis of most ecosystems, the loss of plant species will impact animals as well. Several factors may limit the ability of trees to shift their ranges. First, seed dispersal by wind or by birds may not be fast enough to keep pace with climate change. In addition, trees are long-lived species with long maturation times, and it takes a considerable amount of time for forests to become fully established in new areas. In terms of altitudinal shifts, soils at high altitudes tend to be poorer than at lower altitudes. Consequently, some species may not be able to colonize at higher elevations.

In the United States, the Forest Service believes that Eastern hemlock, yellow birch, beech, and sugar maple forests will gradually have to shift their ranges northward by 300 to 600 miles if projected warming trends become a reality. Several of these ecosystems are likely to be severely limited by warming, however, and are likely to die out, along with the wildlife they shelter. Studies by World Wildlife Fund International report that more than half the world's parks and reserves could be threatened by climate change. Some U.S. parks believed to be particularly vulnerable include the Florida Everglades, Yellowstone National Park, the Great Smoky Mountains, and Redwood National Park in California.

Global warming will also threaten ecosystems in unexpected ways. In 2002 extensive forest damage was reported on the Kenai Peninsula near Anchorage, Alaska. Over 38 million dead spruce trees, some of them over a hundred years old, were cleared from 4 million acres of forest habitat. The cause of this catastrophe was an explosion in the number of spruce bark beetles. Spruce bark beetles have always preyed on spruce trees in the Kenai Peninsula, but have been reproducing much more quickly because of warm temperatures. This represents the worst insect decimation of forests ever reported in North America.

CORAL BLEACHING.

Coral reefs are among the ecosystems most immediately threatened by global warming. (See Figure 3.15.) Coral reef habitats are found in coastal marine waters in tropical areas, and are among the richest and most diverse of marine ecosystems. In fact, one-quarter of all marine species are found in coral reefs. The corals that form the basis of this ecosystem normally have a close relationship with different species of algae. This relationship benefits both members—the algae receive shelter and protection within the calcium carbonate skeletons of corals, and the corals receive nutrients from the algae. Coral bleaching occurs when the corals eject the algae with which they normally live. This process is called bleaching because the corals lose their normally bright colors and take on a stark, white appearance. Coral bleaching has been shown to result from unusually warm oceanic water temperatures. Coral may recover after a bleaching episode when temperatures cool down again and the algae return. However, if the ejected algae die during a bleaching episode, the corals are doomed as well.

Widespread coral bleaching was reported beginning in the 1990s. In the spring of 2002 coral bleaching affected numerous coral reef ecosystems, including the Great Barrier Reef off the coast of Australia, the largest coral reef in the world. This is the second major bleaching event in four years, and it is believed to be extending throughout tropical Pacific coral reef systems. Professor Ove Hoegh-Guldberg, a leading authority on corals and coral bleaching, predicts that if warming trends continue, all coral will be extinct—and the diverse coral reef ecosystems lost—by 2030.

TURTLES AND TEMPERATURE-DEPENDENT SEX DETERMINATION.

Turtles and other reptiles, such as lizards and crocodilians, are characterized by an unusual sex determination system called temperature-dependent sex determination. This differs from the chromosomal system familiar in humans and other mammals, where two X chromosomes (XX) result in production of females and an X and a Y chromosome (XY) lead to males. In species with temperature-dependent sex determination, sex depends on the temperature at which egg development occurs.

Global climate change has resulted in skewed sex ratios in several turtle species. Generally, warmer temperatures favor the production of females in these species. Among loggerhead turtles in Florida, for example, females made up 87 to 99.9 percent of the hatchling population in 1992, depending on the precise nesting site used. This was traced to warmer sand temperatures on beaches. Among Mississippi painted turtles, almost 100 percent of hatchlings were female in 1994. Continued production of large numbers of females and few or no males could have drastic implications for many turtle populations.

INTERNATIONAL EFFORTS AND GLOBAL WARMING

In order to slow or halt global warming, many industrialized countries are committed to stabilizing or reducing carbon dioxide emissions. The first Bush administration (1989–1992) opposed precise deadlines for carbon dioxide limits, arguing that the extent of the problem was too uncertain to justify painful economic measures. When President Bill Clinton took office in 1993, he joined the European community in calling for overall emissions to be stabilized at 1990 levels by the year 2000. However, this goal was not met. The administration of George W. Bush has shown little desire to address the issue of global climate change. Oil interests in particular have vigorously opposed emissions standards, fearing that these will decrease demand for oil. Many environmentalists believe that fighting global warming will require advances in energy efficiency. Others have promoted a gradual shift from fossil-fuel burning to renewable energy, an idea most industrialized countries have been slow to embrace.

The Kyoto Protocol

The aim of the United Nations Framework Convention on Climate Change is to stabilize global atmospheric greenhouse gases at levels "that would prevent dangerous anthropogenic interference with the climate system." In December 1997 delegates from 166 countries met in Kyoto, Japan, to formulate a plan for reducing greenhouse gas emissions as the first step towards this goal. The task was more complicated and difficult than envisioned in 1995, when parties to the 1992 Rio climate change treaty decided that stronger action was necessary. The "simple" matter of deciding on a reduction target and creating a timetable for reductions broadened into contentious debate on several fronts.

Developed nations, such as the United States, argued that both industrialized and developing countries should be required to reduce greenhouse gas emissions. Developing countries, however, argued that because industrialized nations had caused most of the global warming, and were still emitting the bulk of global greenhouse gases, industrialized nations should bear most of the economic burden of the cleanup. It was ultimately decided that the Kyoto Protocol would address only emissions reductions for developed countries. There was also debate over whether development of carbon sinks—such as through the building of tree farms—could offset emissions targets. Many countries wanted sinks to be excluded, in part because their role in global warming has not been well studied and remains uncertain. However, the United States insisted on this carbon sink clause, which it argued would allow businesses low-cost means for complying with treaty requirements. Finally, the United States successfully battled to allow for emissions trading among nations. This permits businesses or countries to purchase less expensive emissions permits from foreign countries that do not need them, rather than cutting emissions.

In the end, the final version of the Kyoto Protocol called for industrialized nations to reduce emissions from 1990 levels by an average of 5 percent by 2008–2012. It was signed by over 170 nations, including the United States, which committed to legally binding emissions reductions of 7 percent below 1990 levels. European Union nations were required to reduce emission by 8 percent, Japan by 6 percent. However, ratification by 55 nations, jointly responsible for 55 percent of 1990 emissions, is required for the treaty to enter into force.

The United States has made no move towards ratifying the Kyoto Protocol since signing it. In fact, President Bush confirmed in March 2001 that the United States would withdraw from the Kyoto Protocol. Bush said that he believed the emissions reductions would be too costly. Christine Todd Whitman, Bush's appointed head of the Environmental Protection Agency, said, "We have no interest in implementing that treaty." The United States was responsible for 25 percent of global emissions in 1990, and it was widely believed that the treaty could not enter into force without U.S. ratification. Despite the withdrawal of the United States from the treaty, however, other countries, including the European Union, Japan, and Canada, have gone ahead with a modified version of the protocol. The Kyoto Protocol is one of several international treaties enjoying broad international support in which the United States has not participated. President Bush has since proposed alternative strategies for dealing with global warming based on tax incentives and volunteer emissions reductions by industry. These plans have been widely attacked as vague and unenforceable.

In June 2002 the Bush administration's U.S. Climate Action Report 2002 (U.S. Department of State, May 2002) conceded first, that global warming exists and is largely the result of human activity, and second, that global warming will cause substantial and far-reaching effects in the United States. The Bush administration has voiced support for adapting to these changes rather than adopting serious measures to reduce greenhouse gas emissions. Soon after the release of the report, President Bush, when asked if he planned any new initiatives to combat global warming, responded, "No, I've laid out that very comprehensive initiative. I read the report put out by the bureaucracy. I do not support the Kyoto treaty. The Kyoto treaty would severely damage the United States economy, and I don't accept that. I accept the alternative we put out, that we can grow our economy and, at the same time, through technologies, improve our environment."

In December 2003 Vladimir Putin, the President of Russia, announced that Russia, the second largest producer of greenhouse gases after the United States, also would not ratify the Kyoto Protocol. However the European Union continues to be enthusiastic about the importance of the agreement, and announced in December 2003 that it was on target for meeting emissions reductions.

U.S. Public Opinion

A November 1997 Gallup Poll suggested that despite their concern about global climate change, Americans were unlikely to support strict measures regarding greenhouse gas emissions. Sixty-nine percent of respondents did not think global warming would be a threat in their own lifetimes, but 65 percent believed it would be a problem in their children's lifetimes. Even so, 48 percent said they were unwilling to reduce global warming if costs for energy went up. (However, 44 percent said they were willing to pay higher energy costs.) An even greater percentage—54 percent—said they would be unwilling to take steps to reduce global warming if unemployment would rise as a result.

Gallup conducted another survey on environmental attitudes in April 2001, coincident with the annual celebration of "Earth Day." Regarding global warming, most Americans surveyed said that they believe global warming's effects will be visible in their lifetimes. One-third of those surveyed said they worry about global warming "a great deal." In fact, a quarter of Americans believe that "immediate and drastic" action must be taken to help preserve environmental resources. A majority, 57 percent, also said that environmental concerns should take precedence over economic considerations when these clash, as they often do. Americans also disagree with several choices made by the Bush administration, in general favoring environmentally friendly choices on issues such as regulating industrial emissions, drilling in the Arctic National Wildlife Refuge, and participating in the Kyoto Protocol on global warming.

Finally, a March 2003 Gallup survey revealed that 75 percent of respondents favored increased enforcement of environmental regulation, and a similar proportion were in favor of mandatory controls on carbon dioxide emissions and other "greenhouse gas" emissions. Fifty-five percent were opposed to opening the Arctic National Wildlife Refuge to oil companies. However, in this poll, respondents were more evenly divided on the question of environmental concerns vs. energy supplies. Forty-nine percent agreed that environmental protection should be a priority even at the risk of limiting energy supplies, while 45 percent took the opposite position.