Global Warming Reports

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Executive Summary

Executive Summary

The growing threat of global warming, air and water pollution, and rising energy costs are a few of the many problems that result from our current over-reliance on petroleum-based transportation fuels. Alternative transportation fuels, in conjunction with an array of other energy-related strategies, have the potential to help mitigate these problems—if
public policy prioritizes those fuels that can deliver the greatest benefit for the environment and the American people.

America’s dependence on oil for transportation causes massive environmental impacts. 

• Emissions from transportation accounted for 33 percent of carbon ioxide emissions in the United States in 2005. Gasoline and diesel were responsible for 78 percent of transportation-
sector emissions.
• Global warming is a growing threat to the environment and our way of life.

Within a century, the average world temperature could increase by another 2 to 11.5°F. Sea level could rise by 7 to 23 inches, and snow and ice cover will continue to contract.

• Our heavy reliance on petroleumbased fuels has also created widespread air and water pollution.

Alternative transportation fuels can reduce our dependence on petroleum, but vary greatly in their impact on the
environment.

Corn-based ethanol has greater lifecycle global warming emissions than gasoline, when produced at the high volumes
forecast for coming years and in ways that increase demand for cropland worldwide.

Corn-based ethanol can also contribute to air pollution problems if used in lowpercentage blends in gasoline and may potentially
trigger significant environmental impacts from increased farming.
Cellulosic ethanol made from agricultural residues or from crops grown on abandoned or marginal cropland may achieve emission reductions with less environmental impact, but is still in the very
early stages of development.

Biodiesel is generally recognized to produce less air pollution than conventional diesel, but soybean-based biodiesel produces more global warming pollution than conventional diesel when it is produced in ways that increase demand for cropland worldwide.

Oil crop production is land-intensive, spurring cultivation of new land and resulting in high emissions. Biodiesel made from waste oil is 98 percent cleaner than conventional diesel, but supplies are
extremely limited.

Electricity can be used to power “plug-in hybrid” vehicles and all-electric vehicles, both of which draw electricity from the
power grid. Because electric motors are far more efficient than internal combustion engines, vehicles that use electricity
almost always produce less global warming pollution than gasoline vehicles, even when the electricity used to fuel them
is generated from coal. The benefits are even greater when vehicles are fueled with renewably generated electricity.

However, few electric vehicles are currently available
to consumers.

Natural gas reduces air pollution and global warming pollution compared with gasoline vehicles. But natural gas fueling infrastructure is expensive and domestic supplies of natural gas are both finite and increasingly constrained.

Hydrogen has long been touted as the transportation fuel of the future. But the environmental impacts of hydrogen depend greatly on how it is produced, and hydrogen-powered vehicles are still a long way from being available to American consumers.

Coal-to-liquids fuels would vastly increase global warming pollution from transportation, while exacerbating environmental
impacts from coal production. Even if emissions from coal-to-liquids plants are captured and sequestered underground, coal-to-liquids fuels are likely to be no better, in global warming pollution terms, than today’s petroleum-based fuels.

America needs a comprehensive strategy to reduce global warming pollution from transportation. Low-carbon
transportation fuels can play an important part in that strategy.
To reduce global warming pollution from transportation, America must reduce the amount of miles we drive, use more ef-
ficient vehicles, and shift to lower-carbon fuels. A low-carbon fuels strategy for the United States should:

1) Combine the most promising approaches to maximize environmental benefits. America should work to make vehicles
more fuel efficient, reduce liquid fuel consumption by increasing the use of electricity (in the short-term, through plug-in hybrids), and replace a significant share of the liquid fuel that remains with lowercarbon options. Such a comprehensive approach can slash per-mile global warming pollution from vehicles by as much as 74
percent compared to conventional gasoline vehicles.

2) Develop fuels with long-term potential. Natural gas, for example, has the potential to reduce global warming pollution in the short term, but has little long-term potential as a transportation fuel due to limited domestic gas supplies. Some sources of cellulosic ethanol have comparatively lower life-cycle global warming emissions, but technological breakthroughs and infrastructure developments will be required before the fuel becomes widespread. Public policy should emphasize the development of infrastructure to support promising long-term fuel options over those with only short-term potential.

3) Set stringent environmental standards and mitigate environmental and social impacts. America will be more likely to reduce the nvironmental impacts of transportation fuels if we set stringent environmental standards for those fuels. The first step
should be to establish a low-carbon fuel standard that encourages the development of fuels with lower life-cycle global warming emissions. Standards should also be developed and implemented to mitigate the impacts of alternative fuels on the quality of our air, water and natural ecosystems.

Achieving large reductions in global warming pollution from cars and light trucks in the years to come will require strong public policies. Necessary steps include:

• Adopting requirements to lower the carbon content of transportation fuels and rejecting policies to promote fuels
that would make the problem worse.

• Requiring that by 2020, all new vehicles are capable of using lower carbon fuels, whether electricity or biofuels.

• Supporting additional research into cultivation techniques for cellulosic feedstock and into technologies for converting cellulosic feedstocks, especially waste, into fuel.

• Improving vehicle fuel economy and pursuing measures to reduce total driving. These measures would further cut global warming emissions and reduce our vulnerability to rapid changes in the global petroleum market.