Carpooling isn't just for soccer practice anymore.

Photo by Hysterical Bertha |

I’ve always wondered about the specifics of how alternative methods to passenger car commuting would affect greenhouse gas emissions. Many people (including some of our own writers!) have heard about the benefits of carpooling or efficient route planning, but never how big the benefits are. Thankfully, researchers are beginning to produce newer, more updated and more accessible documents to inform the average citizen. An example of one of these documents is a recent report released by the Pew Center on Global Climate Change in the United States.

Based out of Arlington, Virginia, the Pew Center aims to bring together the necessary individuals (such as politicians, policy makers and researchers) to come up with new approaches for addressing climate change. In January of 2011, the center released a report entitled “Reducing Greenhouse Gas Emissions from U.S. Transportation.” This study investigated how emissions in American transportation can be reduced from action in three areas: technology, policy and public attitude. A collaboration between multiple researchers and organizations from across the U.S., the 103 page report provides insightful commentary on the current state of transportation emissions, which account for 27% of the greenhouse gas emissions in the country.

The report details that ‘light-duty vehicles’ (passenger cars and light trucks) currently account for nearly three fifths of the total energy use and greenhouse gas emissions of the U.S. transportation sector. While the fuel efficiency of light-duty vehicles is expected to increase in the future from its current average of 26 miles per gallon (roughly 11 km per litre), the authors of the report urge that more changes need to be made than just waiting for fuel efficiency to increase. Options suggested include alternative fuels, reducing traffic congestion, and reducing the current priority of high acceleration performance over fuel economy. However, some of the biggest impacts that can be made are from the drivers themselves.

The average number of passengers in household vehicles in the US is 1.1 for work trips and 1.6 for overall trips. Currently, only 10% of US commuters carpool on their trips to work, which is on the decline from the 1980 statistic of 20%. The Pew Center’s report outlines that carpooling programs and carpool lanes can be expanded in their usage to help cut down on work trip related emissions. On a realistic level, the report projected that a moderate to high increase in the usage of carpooling programs could reduce the total greenhouse gas emissions by the US by 0.4 to 2.0 percent! This is a huge number when one considers that the USA has the world’s largest transportation system and is the world’s second largest greenhouse gas emitter! To crunch some numbers, in 2008, the US’ total greenhouse gas emissions were over 7 thousand million metric tons of greenhouse gases. A 0.4% reduction in this would be over 280,000 metric tons of greenhouse gases saved. This amount saved is roughly the equivalent of 50 million Americans driving their cars for 1 year! So the next time somebody asks you to carpool, buckle up!


To check out the Pew Center on Global Climate Change view their website at