You asked for an overview of the issues regarding global climate change, commonly referred to as global warming. The information in this report is derived from research published by the Climate Action Plan recently submitted by the Bush Administration to the United Nations (http: //www. epa. gov/globalwarming/publications/car/index. html), the National Research Council (http: //www4. nas. edu/onpi/webextra. nsf/web/climate), the United Nations (http: //www. ipcc. ch/), and the National Conference of State Legislatures (http: //www. ncsl. org/legis/LBRIEF/legis68. htm).

SUMMARY

There is a growing consensus that human activities, such as the burning of fossil fuels and deforestation, are increasing atmospheric concentrations of carbon dioxide and other "greenhouse gases" and that this trend may substantially affect the global climate. Assuming that concentrations of greenhouse gases will continue to rise due to population and economic growth, computer models suggest that average global surface temperatures will rise between 3 and 11 degrees Fahrenheit by the end of this century. While attention has focused on global warming, the models also project that there will be substantial changes in precipitation, humidity, storm activity, and sea levels, with major differences by region. These changes may harm ecosystems, increase drought, threaten coastlines, and lead to more destructive storms. However, some of the changes may prove beneficial, for example by extending the growing season in the northern United States and Canada. Although the computer models have become increasingly sophisticated, there remain significant uncertainties as to the timing, geographical extent, and intensity of global climate change.

In response to the research, 169 countries signed a treaty on greenhouse gases in Kyoto, Japan in 1997. The treaty calls upon the United States to reduce its emissions of greenhouse gases by 7% of their 1990 levels by 2012. The treaty calls upon other developed counties to make similar reductions, but does not require reductions in developing countries. Although the United States signed the treaty, neither the Clinton nor the Bush administration submitted it to the Senate for ratification. The Senate adopted a resolution that would require developing nations to reduce their emissions as a condition of ratification. The Bush Administration has instead proposed voluntary measures to reduce the amount of greenhouse gases emitted per million dollars of gross domestic product. Legislation is also being developed in Congress on this issue. At the state level, Connecticut and several other states have adopted initiatives to address global climate change. Legislation pending in California would require the state to reduce greenhouse gas emissions from vehicles, which could involve higher gasoline taxes or similar measures.

GREENHOUSE GASES

Greenhouse gases, including carbon dioxide, methane, nitrogen oxide, and several compounds containing chlorine and fluorine, exist in trace amounts in the atmosphere. The carbon dioxide, methane, and nitrous oxides are partially the products of natural processes and partially the result of human activity. For example, carbon dioxide is produced by the combustion of fossil fuels (coal, oil, and natural gas) in electric power generation, buildings, and vehicles, as well as by several natural processes. Methane is produced by animals and landfills. Other greenhouse gases, such as fluorine and chlorine compounds, are entirely man-made. While carbon dioxide is the largest component of greenhouse gases (82% of U. S. emissions), other gases have a far larger effect on the atmosphere on a molecule-to-molecule basis. Concentrations of all of the greenhouse gases in the atmosphere began increasing after the Industrial Revolution and are anticipated to continue rising as a result of population and economic growth.

The gases act like a greenhouse, retaining part of the solar radiation that bounces off the earth. While the gases also reflect some of the solar radiation into space, the net effect is to increase the earth's surface temperature. In the absence of the greenhouse effect, the earth's temperature would be about 55 degrees less than it currently is.

GLOBAL CLIMATE CHANGE MODELS

The United Nations World Meteorological Organization and the United Nations Environment Program established the Intergovernmental Panel on Climate Change (IPCC) in 1988. In 1996, IPCC determined that the average global temperature has increased by approximately 0. 9 degrees Fahrenheit over the past century. The panel concluded that it was unlikely that the change was entirely due to natural forces and that the evidence from several sources suggested that there was a discernible human influence on global climate. In its first assessment, IPCC models suggested that the average global temperature could increase by 1. 6 to 6. 3 degrees by 2100. The models are complex computer simulations that describe air and water currents, changes in carbon dioxide "sinks" such as forests, and energy transport mechanisms. In 2000, the National Research Council found that warming has been particularly notable during the previous 20 years, and that retreating glaciers, rising sea levels, and longer growing seasons in some areas provide further evidence for continued warming.

The IPCC's third assessment, issued in 2001, found a firmer association between human activities and climate. It identified several dozen atmospheric, ecological, and economic data series that provide evidence that most of the warming observed over the last 50 years is attributable to human activities (the data are available on the panel's Website, http: //www. ipcc. ch/pub/tar/syr/004. htm#tabspm1. ) In addition, the panel projected a higher range of potential warming, between 3 and 11 degrees Fahrenheit over the next 100 years. The panel notes that this warming is without precedent in the last 10,000 years. In addition, the assessment anticipates that the evaporo-transpiration process by which water evaporates from the earth's surface and returns as precipitation is expected to speed up. This means that it would rain more, but the rain would evaporate faster, leaving soils drier during the growing season.

The U. S. 's most recent climate action plan, submitted to the United Nations in late May 2002, states that continued growth in greenhouse gas emissions is likely to increase average temperatures in the U. S. by 3 to 9 degrees over the next century. In addition, the summertime heat index is projected to rise quite sharply due to increasing humidity levels. The plan notes that climate change will interact with such issues as air and water pollution, habitat fragmentation, wetland loss, coastal erosion, and reductions in fisheries in ways that are likely to compound these stresses.

The models suggest that the climate changes could vary dramatically by region. They indicate that precipitation could increase markedly in some areas while falling in other areas. Global climate change could have some counter-intuitive effects. For example, one model suggests that the melting of the Artic ice cap could weaken the Gulf Stream as it approaches northern Europe, thereby substantially decreasing the region's average temperature.

There have been challenges to the findings of IPCC and other research groups. Critics argue that many uncertainties remain surrounding the nature and direction of earth's climate itself, as well as the timing, rate, magnitude, and extent of model-projected global warming. They note that several of the models, when run backwards in time, predict more warming over the past 100 years than was actually measured at the Earth's surface. Still other critics argue that the models understate the role of other forces, such as solar and ocean cycles, in shaping the world's climate. In its climate action plan, the Bush Administration proposes further research on more than a half dozen areas of scientific uncertainty, including climate feedback mechanisms and the regional and local effects of climate change.

Some scientists and economists have argued that while significant global climate change is likely, the solutions that have been suggested to meet the requirements under the Kyoto treaty (discussed below) would be extremely expensive. They argue that money would be better spent in addressing other problems, particularly in developing countries. A March 21, 2002 article in the Guardian of England (Website http: //image. guardian. co. uk/sys-files/Guardian/documents/2001/08/14/warming. pdf) presents this argument in detail.

POSSIBLE IMPLICATIONS OF GLOBAL CLIMATE CHANGE

The changes described above have the potential to significantly affect ecosystems and human populations. In its climate action plan, the Bush Administration notes that several American ecosystems, such as alpine meadows in the Rocky Mountains and some barrier islands, are likely to disappear entirely as a result of climate change. Other ecosystems, such as southeastern forests, are likely to experience major species shifts or break up into a mosaic of grasslands, woodlands, and forests. Some of the ecological values, such as natural filtration of water, lost through the disappearance or fragmentation of natural ecosystems are likely to be costly or impossible to replace. On a global basis, the combined effects of increased carbon dioxide levels, climate change, and other stresses are very likely to cause large, possibly irreversible, impacts to coral reefs that are essential to many ocean ecosystems.  

Among the most widely anticipated effects of climate change are substantial changes in precipitation patterns. New or worsening droughts could reduce supplies of clean, fresh water to the point where there are major threats to public health in developing countries. In the U. S. , the acceleration of the evaporo-transpiration process is projected to create a greater susceptibility to forest fires and the subsequent loss of the vegetation that helps to control erosion and sediment flows. The climate change models simultaneously predict an increase in heavy precipitation events, such as downpours. Such events are likely to flush more contaminants and sediments into lakes and rivers, degrading water quality. Reductions in the snowpack due to higher temperatures are likely to be especially important in the West and Alaska. This could affect not only the availability of water for consumption and irrigation but also for electricity production.

The change in climate could significantly affect agriculture. Increased summer dryness could reduce mid- latitude crop yields by 10 to 30%, and it is possible that leading grain-producing areas such as the Great Plains would experience more frequent droughts and heat waves.

Global climate change may raise sea levels, threatening low-lying coastal areas and small islands. The average global sea level has already risen by around 4 to 8 inches during the past century, in part due to geological trends unrelated to climate. Global warming may cause a further rise of about 7 inches by the year 2030, due to melting of the polar ice caps and expansion of seawater as it grows warmer. If the current trend in greenhouse gas emissions continues, the rise could amount to 4 to 35 inches above current levels by the year 2100. The most vulnerable land would be the unprotected, densely populated coastal regions of some of the world's poorest countries. Bangladesh, whose coast is already prone to devastating floods, would be a likely victim. However, even in developed countries, higher sea levels are likely to intensify erosion and endanger coastal structures. The U. S. climate action plan notes that because most of the country's Atlantic and Gulf coasts have gentle slopes, even a small rise in sea level can move the shoreline far inland. The rise will be particularly important if the frequency or intensity of storm surges or hurricanes increases.

While it is unclear whether the climate changes forecast in the models would increase the frequency of hurricanes, the ones that do develop are likely to have higher wind speeds and produce more rainfall. As a result, they are likely to cause more damage, unless more extensive (and therefore more costly) adaptive measures are taken, including reducing the increasing exposure of property to such extreme events.  

In 1997, the Environmental Protection Agency (EPA) prepared descriptions of possible climate changes in each state. Based on previous research, it estimated that Connecticut's average temperature could increase by 2 to 8 degrees by 2100 and precipitation increase by as much as 40%. (As noted above, climate change models developed since 1997 have led to larger forecast increases in average temperature. ) Such an increase in average temperature could raise the number of heat-related deaths by 20% or more and worsen smog, which aggravates a number of respiratory illnesses. The increased warmth could expand the habitat of insects carrying eastern equine encephalitis and Lyme disease. Climate change could also impair the state's tourism industry as warmer temperatures result in the replacement of trees, such as maples, with brilliant fall foliage with less colorful pines and oaks. The EPA study estimated that the sea level is likely to rise 22 inches by 2100. It estimated the cost of preventing damage from such a rise at between $ 500 million and $ 3 billion.

Some of the projected outcomes of climate change could be beneficial. For example, increased carbon dioxide levels would increase forest productivity. Agriculture in areas such as the northern United States, Canada, Russia, and Japan might benefit from higher temperatures and longer growing seasons. Warmer winters may reduce cold-related heart attacks, and higher temperatures in tropical regions may reduce transmission of schistosomiasis, a major parasitic disease.

POLICY INITIATIVES

Kyoto Treaty

The world's nations have been meeting annually under the auspices of the United Nations Convention on Climate Change, which arose out of the 1992 Earth Summit in Rio de Janeiro. In Kyoto, Japan, in December 1997 169 nations agreed on legally binding reductions in greenhouse gas emissions for the developed nations. The treaty would require the United States to reduce its emissions of greenhouse gases by approximately 7% below 1990 levels by 2012. The United States signed the Kyoto Protocol on November 12, 1998. However, the Clinton Administration did not submit it to the Senate for ratification, because it did not require developing nations to limit their greenhouse gas emissions. The Senate had passed a resolution indicating that such commitments would be necessary for its approval.

To go into effect, the treaty must be ratified by 55 nations that collectively account for at least 55% of the 1990 greenhouse gas emissions. As of June 2002, 70 nations (including the 15 members of the European Union and Japan) had ratified the treaty. The nations account for approximately 35% of 1990 emissions. The U. S. accounts for about 25% of the world's greenhouse gas production.

Federal Initiatives

The Bush Administration has opposed the treaty arguing that it would harm the U. S. economy and is unfair in that it does not require developing nations to reduce their emissions. Instead, the administration has proposed reducing the "intensity" of greenhouse gas emissions as part of its Clear Skies initiative. Under the proposal, the goal would be to reduce by 18% the number of tons of these gases emitted per million dollars of gross domestic product by 2012. Under current economic forecasts, this would result in a 4. 5% reduction in forecast emissions, less than called for under the Kyoto treaty. To promote this goal, the proposed budget for federal FY 2002-03 would increase spending on global climate change activities from $ 700 million to $ 4. 5 billion, primarily by increasing relevant tax credits. The administration has also proposed increased assistance to other nations for advanced energy demonstration projects.

Several bills addressing greenhouse gases are before Congress. The Senate Environment and Public Works Committee will soon begin writing a comprehensive air pollution bill introduced by Sen. Jeffords, dealing with carbon dioxide and nitrogen oxides (another type of greenhouse gas) as well as mercury and sulfur dioxide. It will also consider another four-pollutant bill with less stringent requirements that has been supported by some electric utilities.

State Initiatives

California. Pending legislation (AB 1058) in California would control carbon dioxide emissions from vehicles. The bill would require the state Air Resources Board to adopt regulations to require that passenger vehicles and light duty trucks achieve the maximum feasible reduction in carbon dioxide emissions. The board would have to adopt the regulations by January 1, 2004, but they could go into effect no earlier than January 1, 2005. Among the options the board has identified for possible inclusion in the regulations are imposing a tax of two cents per vehicle mile traveled, raising the gasoline tax by 50 cents per gallon, and imposing a charge on vehicles that emit high amounts of carbon dioxide. The bill has passed both chambers and is awaiting final reconciliation.

Connecticut. Connecticut has adopted several provisions to address global climate change. PA 90-219, "An Act Concerning Global Warming," established a broad range of energy conservation measures, including revisions to the building code to maximize energy efficiency and requirements that the state purchase energy efficient appliances and vehicles. It also established goals for improving public transportation and requires the Connecticut Public Transportation Commission to monitor progress in achieving them. The act allows the environmental protection commissioner to require trees or grass to be planted in connection with air discharge permits.

New Hampshire. In 1999, New Hampshire adopted legislation establishing a registry of greenhouse gas emissions. The registry will help emitters establish records of their reductions, which can be used in voluntary and market-based systems.

This session, the New Hampshire legislature passed legislation (HB 284) that places a 5 million ton per year cap on carbon dioxide emissions from existing fossil fuel power plants. The legislation also imposes caps on three other pollutants that are less relevant to the global warming debate, mercury, sulfur dioxide, and nitrogen oxides. The caps go into effect in 2007. The legislation allows electric utilities to comply with the caps through an emissions trading and banking program.

New Jersey. In 2000, New Jersey governor Christine Whitman announced the release of a greenhouse gas action plan that had a goal of reducing 2005 emissions to 3. 5% below their 1990 levels. The plan found that 92% of the state's emissions were carbon monoxide from fossil fuel combustion, with the transportation sector creating the largest share of emissions. The plan, which is entirely voluntary, promotes increased energy efficiency and innovative technologies such as microturbines and fuel cells. In addition to the plan, the state's electric restructuring law provides funding for energy efficiency and renewable energy, and requires suppliers to obtain part of their power from renewable resources (Connecticut's law has similar provisions. )

Oregon. Oregon adopted legislation in 1997 that requires that any new gas-fired power plant emit at least 17% less carbon dioxide than the most efficient gas-fired plant in the country. (A substantial majority of new power plants across the country burn natural gas, which creates carbon dioxide. ) If the plant cannot meet this standard, the developer must (1) use cogeneration, a technology that increases energy efficiency by simultaneously using the electricity and hot water created in the generation process; (2) invest in mitigation efforts, such as renewable energy and tree-planting projects to offset the excess emissions; or (3) make payments to the Oregon Climate Trust Fund, which would invest in carbon dioxide offset projects.

Wisconsin. The Wisconsin Department of Natural Resources, with funding from the EPA and others, conducted four studies in the 1990s to better understand global climate change and identify possible responses. The department projected that climate change could seriously damage the state's agriculture, forestry, and tourism industries. One of the studies identified the costs of various emission reduction strategies, including energy efficiency. Another study estimated that adopting energy efficiency changes could increase the gross state product by $ 41 million in 2010 and create 8,500 new jobs. In 2000, the state adopted legislation to require the department to establish a registry of voluntary emissions reductions.

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