Walking Is NOT Carbon-Neutral and Zero Emission
A Prius is more energy efficient over its lifetime than a Hummer, right? Walking has to be much more environmentally-friendly than driving a car for a short trip, doesn't it? Well, as economist Steven Levitt points out, "When it comes to saving the environment, things are often not as simple as they seem at first blush." This CD post yesterday showed that driving a Toyota Echo is 5X more energy efficient as a Toyota Prius, and even a Hummer H3 might be better than a Prius over the lives of the vehicles.
Could it also be the case that driving a car is actually "more green" than walking? From NY Times science columninst John Tierney:
Chris Goodall, the author of “How to Live A Low-Carbon Life," is a member of the Green Party in Britain and a devout environmentalist. But he also questions how much good is being done by eliminating short trips by car. In fact, he says that in some circumstances it’s better to drive than to walk.
How can that be? Because Mr. Goodall takes into account something that a lot of environmentalists don’t: the human energy expended in averting fossil-fuel use. “Walking is not zero emission because we need food energy to move ourselves from place to place,” he writes. “Food production creates carbon emissions.”
If you walk 1.5 miles, Mr. Goodall calculates, and replace those calories by drinking about a cup of milk, the greenhouse emissions connected with that milk (like methane from the dairy farm and carbon dioxide from the delivery truck) are just about equal to the emissions from a typical car making the same trip. And if there were two of you making the trip, then the car would definitely be the more planet-friendly way to go.
Comment: Perhaps Native Energy and other groups that sell carbon offsets could add walking to their list of activities for which individuals can buy offsets?