Environmental Defense has published a report which shows that US drivers are causing a disproportionate part of world car-generated pollution because, in addition to having a high proportion of the world's cars, they drive them more, and the cars are less fuel efficient.
(click for larger version)
The report outlines the numbers:
- There are 202 million passenger vehicles in the USA, out of 683m worldwide;
- The average US passenger vehicle travels 11,000 miles a year, nearly a third more than cars elsewhere (8,500 miles);
- the US fleet has poor fuel efficiency, at under 20 MPG, and emit 15% more Carbon per mile than vehicles elsewhere.
Gasoline contains 5.3 pounds of carbon per gallon, essentially all of which ends up in the atmosphere as CO2 when the fuel is burned. Thus, the average U.S. car puts over a ton and a half of carbon into the air each year.
The most depressing item is that things are getting worse:
The fuel efficiency of 2004 model year cars of almost all manufacturers is lower than that of their whole fleets already on the road (only BMW and Mitsubishi do a little better) - which means that things are actually getting worse on the MPG front.
And that comes despite (small) improvements in the fuel efficiency of each vehicle class, as shown below, because Americans are icnreasingly buying the worst performers, light trucks, SUVs and pick up trucks.
Another way to see it:
And while we have managed to reduce emissions of other pollutants, carbon emissions are directly proportional to fuel consumption as they are generated by the combustion of the gasoline:
A big part of the Energize America plan is to change this through a "feebate" mechanism, with a bonus if you buy a car with above fleet average fuel efficiency, and a penalty if you buy a car with a below average fuel efficiency. Such a plan appears urgent in view of the fact that current vehicle sales do nothing to improve overall MPG, but it's a long term solution.
the U.S. light vehicle stock now has a "half-life" of roughly eight years; in other words, 50% of vehicles are replaced within that time. It takes 16 years for the fleet to be 90% replaced in terms of the carbon emitted during driving. In short, the choices made regarding new vehicles influence emissions for many years to come.
Now one may consider that carbon emissions from US cars amount to only 5% of total world carbon emissions, and that a big effort will be required for smallish results overall, but that's missing the point: we need to fight carbon emissions on every front at the same time, and this is one where individual choices can have a very real overall impact if everybody participates.
Beyond the obvious long term solution coming from switching to more fuel efficient vehicles, the report notes that behavior have changed in recent years:
- The number of miles for shopping trips steadily increased since 1969, and grew by 40% from 1990 to 2001, as a result of increased shopping trips and extended trip lengths;
- The share of light trucks has increased from less than a third to more than half in a few years.
These changes can be reversed by a multiplication individual decisions as well.