Considering Carbon Costs

Mike Berners-Lee calculates the carbon cost of riding a mile on a bicycle to be 65 grams, if you power yourself with a banana; 260 grams if you use cheeseburgers for fuel. (For the metrically impaired, that's about 2.2 ounces for the banana, or 9 oz. for the burger.)

He includes in that figure the cost of manufacture of the bicycle, but he doesn't deduct the amount of energy you would have burned in food if you were just sitting around on the couch, or, say, driving your car.

More information is in his book, How Bad Are Bananas? The Carbon Footprint of Everything, which you can't buy yet in the United States. Probably because they're busy converting all the metric units into ones Americans can understand.

By way of comparison, the average passenger car emits almost a pound of carbon for every mile you drive. That apparently does not include the carbon released during manufacture of the vehicle. Public transit averages around half a pound of carbon emissions per passenger mile.

While straphanging or reading a book on the train, though, you're also burning up the calories you ate for breakfast: not quite at the rate you would be if you were biking the distance, but that far off: unless we're ultra-marathoners or ironman triathletes, most of the calories we burn are expended in basal metabolism, and not in exercise.

So... get out of the car, get on the bike, or just hoof it.