A gallon of gasoline is equivalent to about 28,972 calories. Each month, the average American uses 83,250 calories consumed as food; she "burns" 2.87 gallons of food-equivalent gasoline sitting around her house, watching TV, and vegetating in her cubicle, happily spewing the world-ending by-products of her internal combustion of whole grain rice, granola, and organic fair trade coffee.
So, back to our original question. How much extra C02 do you expel as you tool around town on your bike, or on your stationary bike at home? People don't often think of a bicycle in this way, but let me assure you, the C02 released from your lungs is exactly the same as the stuff coming out the back of your car.
Walking increases the gas mileage. A 190 lb person walking at three MPH would get 308 miles to the gallon; and smaller people get better gas mileage. A 130 lb person running the same mile would get 315 miles to the gallon. So why isn't anyone worried about exercise as a pollutant? Should we not recommend people move as little as possible to avoid a global catastrophe? Further, these calculations don't include exhaust from the human body; methane gas (farts) is 26-30 times more powerful a green house gas compared to CO2, and the average person "passes methane" 14 times per day. Humans generate about relatively high amounts of pollution per unit of work performed. To save the planet from greenhouse gases, we should be encouraging machines and gasoline to do everything they possibly can!
Depending on what you eat, it may actually cost less to drive to the store. If you were to live on Amy's frozen meals, which I have been known to do from time to time (Organic, $5 per box, really tasty, $15 per 1,000 calories) you would spend $30 in fuel to jog round trip to a store 7.5 miles away. If you take your regular old unmodified Prius it will cost you 59 cents in fuel (51 MPG in town, 29.4% of a gallon at $2 per gallon). It would cost $1.15 to get there and back in an SUV getting 13 MPG. (Running to the store living on Bic Macs is half price.)
|A very CO2 and methane intensive activity|