But he (Chris Goodall, the author of “How to Live A Low-Carbon Life”) 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.
I’m not sure if Goodall’s reasoning is sound or not, but I’ll remember his thinking in the future to justify my laziness.