In 1996, the Intergovernmental Panel on Climate Change, an international body comprised of more than 300 scientists and climatologists from around the world, completed a report with troubling predictions: The average global temperature could increase by 3.6 to 6.3 degrees Fahrenheit over the next 100 years, in part because of the atmospheric accumulation of carbon dioxide and other so-called greenhouse gases. During the same period, the average sea level could rise 8 to 34 inches as oceans warm and portions of glaciers and ice sheets melt, inundating some wetlands and low-lying coastal areas. Broader weather patterns could change, subjecting some areas to more intense droughts and some to more severe storms and floods, but perhaps extending the growing season in others. The geographic range of some insect-borne diseases, such as malaria, could expand.

The complexity of ecological systems means that there is still considerable uncertainty in making these sorts of predictions. However, the same scientists concluded that human-induced emissions of greenhouse gases (GHG)gases that play a role in trapping heat within the earth's atmosphereare already having a discernible effect on the planet's weather. There are many such gases, but six gases and classes of compounds are particularly important: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), sulfur hexafluoride (SF₆), perfluorocarbons (PFCs), and hydrofluorocarbons (HFCs). These compounds absorb radiation reflected from the earth's surface. Rather than traveling off into space, this trapped radiation transfers its energy to the atmosphere in the form of heat. The first three gases (CO₂, CH₄, and N₂O) occur both naturally and as a result of human activities, and keep the earth from turning into an icebox, like Mars. CO₂ is also removed from the atmosphere through photosynthesis by plants. The other three (SF₆, PFCs, and HFCs) are associated with industrial and other processes such as air conditioning and making aluminum, magnesium, and semiconductors. While the levels of the naturally occurring gases have varied widely over geologic history, the atmospheric concentrations of these three gases and the three synthetic ones have risen dramatically through this century.

In 1992, representatives from the United Nations met in Rio de Janeiro and developed the Framework Convention on Climate Change (UNFCCC), an agreement that calls for stabilization of atmospheric concentrations of these greenhouse gases. A Protocol to this Convention, signed in Kyoto, Japan, in 1997, seeks to control emissions of GHG by setting binding targets for developed countries. For example, the United States agreed to a target of reducing its average annual GHG emissions to 7% below 1990 levels during the period 2008-2012 if and when the protocol is ratified by the United States Senate. By the same period, the European Union agreed to a target level 8% below 1990 levels. Other developed countries such as Australia, Canada, and the Russian Federation also agreed to binding GHG targets. Countries with economies that are considered to be developing or in transition, such as India, China, and most of Africa and South America, were not required to adopt binding GHG targets, although the Protocol encourages these countries to moderate their emissions as their economies grow.

The Kyoto Protocol outlines innovative ways to harness the forces of the global marketplace to meet overall targets without severe economic impacts. In particular, the Protocol outlines mechanisms such as Emissions Trading and Clean Development. Emissions trading, allows developed countries that reduce their target emissions beyond their target to sell emissions credits to others. The Clean Development Mechanism (CDM), allows developed countries to finance emissions-avoiding projects in developing countries and receive credit for so doing. The Kyoto Protocol also allows certain carbon-absorbing activitieslike changes in forest managementto be counted toward a country's GHG budget. These mechanisms allow flexibility in the ways that developed countries meet their target emissions levels, while maintaining the commitment to an overall cap on emissions.

U.S. priorities for achieving the goals of the UNFCCC include binding emissions targets, meaningful participation of developing countries, and market-based approaches that can help to minimize the costs. The United States is also promoting the development of new technologies and alternative energy sources that could result in dramatic future emissions reductions. For example, by adding alcohol from corn and other biomass sources to gasoline, the United States can offset emissions from even the oldest cars on the road.

At this time, no country has adopted a binding regulatory framework to limit greenhouse gas emissions. The United States is seeking ways to encourage businesses to voluntarily reduce emissions before any such framework is in place. Eleven other senators have joined Senator Chafee of Rhode Island in introducing "The Credit for Voluntary Reductions Act" (Senate Bill No 5. 547), to provide credits for voluntary GHG reductions and carbon sequestration (e.g. enhanced forest management) during a ten-year crediting period.

As the United States develops these policies and measures, it must be mindful of the effectiveness, feasibility, and economic impacts of different policies. It must also address how the dynamics of greenhouse gas emissions vary across different sectors, such as electrical generation, transportation, agriculture, industry, livestock, and waste management. These sectors vary considerably in the way they release greenhouse gases, absorb carbon, and respond to different policies and programs.

Emissions from transportation vehicles currently account for just over one quarter of aggregate U.S. GHG emissions, but are growing faster than those from any other major sector. A few important underlying trends include increases in household travel, increases in air travel, and the increased popularity of light trucks and sport-utility vehicles.

Three broad categories of strategies are available to reduce emissions from the transportation sector. First, programs can be implemented to influence the amount and nature of passenger and freight transportation. Second, vehicles can be made more fuel-efficient. Third, shifts can be made to less carbon-rich fuels, or fuel produced from renewable feed stocks like corn.

Regulations for light vehicle fuel economy have been in place in the United States for more than twenty years, and the efficiency of U.S. automobiles is now comparable to that of automobiles in other developed countries. The United States is currently about halfway through a government-industry research partnership to develop vehicles that achieve as much as a tripling in fuel economy by 2004. This will be accomplished by utilizing lightweight materials and technologies such as fuel cells and advanced low-emission diesel engines. The United States has policies in place to encourage the use of alternative fuels like ethanol and methanol, and to make sure that decisions about the design and operation of transportation systems take efficiency into account.

In part because transportation system components like highways, automobiles, and refineries represent such significant investments, market-based approaches like emissions trading could present an important opportunity to meet climate-related objectives at low cost. However, significant work remains to understand how these and other approaches might apply to the transportation sector, and to understand potential implications for businesses and the public.

A Global Approach

A key provision of the Administration's support of the Kyoto Protocol is the meaningful participation of developing nations. Without new abatement policies, greenhouse gas emissions from developing countries may overtake those from developed countries before 2020. In his remarks on last November's international climate negotiations in Buenos Aires, Vice President Gore indicated that our goal must be a global solution that protects future generations while maintaining strong and sustainable economic growth.

Ten U.S. government agencies have pooled resources to support this objective through the U.S. Country Studies Program (CSP), which was announced by the Bush Administration at the 1992 Earth Summit in Rio de Janeiro. The primary objective of the Program is to enhance the capacity of developing countries (and countries with economies in transition) to address the problem of climate change, and to participate fully in the international response to this problem, particularly within the context of the U.N. Framework Convention. Specifically, the CSP has provided financial support, training, technical assistance, computer equipment, data, analytical tools, and information services to 55 participating countries. This expertise has helped partner countries to inventory their emissions of greenhouse gases, and to assess their potential vulnerability to climate change, and approaches to adapting to such change.

Volpe Center Participates in U.S. Effort

In addition, the U.S. is helping participating countries to develop national plans for responding to climate change. These action plans identify and evaluate a portfolio of options for controlling greenhouse gas emissions and increasing carbon sinks. Specialists like the Volpe Center's Kevin Green, an engineer in the Transportation Strategic Planning and Analysis Office, help developing countries to assess their technological options and needs. Through an interagency agreement funded by the U.S. Environmental Protection Agency, Green has been participating in the CSP by helping developing countries to improve their knowledge base for understanding and mitigating transportation-related GHG emissions. For example, the government of Egypt has been considering the potential to reduce emissions through new transit systems and alternative fuels like hydrogen and compressed natural gas (CNG). Drawing upon a range of government-funded and other U.S. research, Green provided Egyptian decision-makers with technical information regarding transit vehicle efficiency, full fuel-cycle emissions for CNG, infrastructure for gaseous transportation fuels, and potential fuel costs. It is expected that this information will help Egypt to make practical decisions about relying on these strategies in any greenhouse gas mitigation plans.

More recently, Green participated in a February 1999 technical team visit to Argentina to discuss that country's plans to adopt a national target for greenhouse gas emissions during the period from 2008-2012. In order to develop the analytical foundation for such a target, Argentina has sought technical assistance in several areas, including emission inventories, transportation technologies, and the development of scenarios and mitigation options for the transportation sector. In conjunction with other Federal specialists, Green provided an overview of U.S. methods for estimating and projecting transportation-related energy demand, past U.S. consideration of policies and programs related to energy efficiency and greenhouse gas emissions, and the outlook for several key transportation technologies and fuels.

Argentine officials also expressed a special interest in hydrogen and compressed natural gas for transportation. Green followed up this initial meeting by providing more detailed guidance regarding these fuels, and he is also discussing options such as hybrid electric propulsion. A technical meeting later this year is being planned to address technologies and mitigation options specific to the transportation sector. The CSP, EPA, and Volpe Center staff are hopeful that this will help provide Argentina with a solid foundation for the development and successful adoption of a realistic Argentine emissions target and climate change action plan.