Driving less, switching to a hybrid or ditching the car entirely are sure-fire ways to reduce your carbon footprint. Barring that, there's something cheap and easy you can do to help cut global CO2 emissions by more than 42 million tons.

Make sure your tires are properly inflated.

Everyone knows under-inflated tires decrease safety and increase fuel consumption, but they also may help create almost as much carbon dioxide as Connecticut emits each year.

Huh?

An analysis by Bridgestone Europe of 20,300 passenger cars in the European Union found 93.5 percent had under-inflated tires. Softer tires increase rolling resistance, forcing the engine to work harder - and burn more fuel. The U.S. Department of Transportation says being down just 5 to 7 pounds per square inch can decrease fuel economy by two to three miles per gallon.

The number-crunchers at Bridgestone figure all of those cars with under-inflated tires are burning an additional 2.14 billion - with a 'b' - gallons of fuel per year - and generating an additional 18.4 million tons of carbon dioxide. That's almost as much as Delaware emits in a year.

We did a little back-of-the-envelope math to see what that might mean on a global scale. There are about 600 million cars in the world, so you're looking at an additional 42.32 million tons of carbon dioxide generated by under-inflated tires, or slightly less than Connecticut emitted in 2005.

Granted, that's by no means a scientific figure. But it gives you a sense of what might be accomplished if everyone took five or 10 minutes a month to check their tires. Don't know how? Check this out.

Photo by Flickr user Victoria Chapman.