U.S. Autos Account for Half of Global Warming Linked to Cars Worldwide

American Cars Emit More Than Their Share of Carbon Dioxide, Study Says

U.S. automobiles and light trucks are responsible for nearly half of all greenhouse gases emitted by automobiles globally, according to a new study by Environmental Defense.

The study, Global Warming on the Road [PDF], also found that the Big Three automakers—General Motors, Ford and DaimlerChrysler—accounted for nearly three-quarters of the carbon dioxide released by cars and pickup trucks on U.S. roads in 2004, the latest year for which statistics were available.

“Cutting greenhouse gas emissions from U.S. automobiles will be critical to any strategy for slowing global warming,” said John DeCicco, author of the report and senior fellow at Environmental Defense, in a press release. “To address global warming, we’ll need a clear picture of what sources are contributing to the problem. This report details, by automaker and vehicle type, the greenhouse gas contributions from America's auto sector, for the first time.”

Excessive Carbon Dioxide Emissions
Carbon dioxide emissions from personal vehicles in the United States equaled 314 million metric tons in 2004. That much carbon could fill a coal train 55,000 miles long—long enough to circle the Earth twice.

Cars and trucks made by GM gave off 99 million metric tons of carbon dioxide or 31 percent of the total; Ford vehicles emitted 80 million metric tons or 25 percent; and DaimlerChrysler vehicles emitted 51 million metric tons or 16 percent, according to the report.

Why U.S. Cars Emit More Carbon Dioxide
While Americans own only 30 percent of the 700 million vehicles that are in use worldwide, the authors of the report found that cars in the U.S. account for a disproportionate amount of greenhouse gas emissions because they are driven farther, have lower fuel economy standards, and burn fuel with higher levels of carbon than many of the cars in other countries.

For example:

  • U.S. cars and light trucks were driven 2.6 trillion miles in 2004, the equivalent of 10 million trips from the earth to the moon.
  • U.S. automobiles had an average fuel economy of 19.6 miles per gallon in 2004, for an average annual consumption of just over 600 gallons of gasoline.
  • Gasoline in the United States contains 5.3 pounds of carbon per gallon. All of that carbon ends up in the atmosphere as carbon dioxide in automobile exhaust when the fuel is burned. So the average car in the U.S. puts more than 1.5 tons of carbon into the air every year.

Drivers have no control over the amount of carbon in the gasoline they buy, but they can control the other two key factors by reducing the number of miles they drive each year and choosing to buy more fuel-efficient vehicles. [For more driving tips that can help you reduce greenhouse gas emissions, see Drive Smart: Fuel Savings Add Up.]

Small Cars Emit More Carbon Dioxide Than SUVs
The study by Environmental Defense found some other surprising facts:

  • Despite the proliferation of SUVs, small cars such as compacts and subcompacts still account for 25 percent (77 million metric tons) of carbon dioxide emissions on the road. The reason is simple: small cars were the top-sellers for a long time, and cars tend to stay on the road for many years.
  • Although SUVs currently trail small cars as sources of carbon dioxide emissions that contribute to global warming (67 million metric tons or 21 percent of all U.S. auto emissions), they will soon be in first place and will remain a leading cause of global warming on U.S. roads for many years.
  • The average new car, led by personal trucks, emits more carbon dioxide than many older cars still in use, so the idea of simply getting rid of older cars to reduce on-road emissions won’t solve the problem.

“Reducing global warming on the road is a shared responsibility,” DeCicco said in a press release. “By underscoring the magnitude of emissions from America's automobiles, this report shows that all actors – automakers, fuel providers, consumers, and various levels of government – can help solve the problem by addressing those aspects of CO2 emissions they can control.”

More information:
Pollution in Overdrive (The Washington Post)