I ask because I came across an interesting challenge to the notion that taking short trips in a car is bad for the planet. This challenge comes from Chris Goodall, the author of “How to Live A Low-Carbon Life.” Mr. Goodall is a member of the Green Party in Britain and a devout environmentalist — he says he has ceased air travel because of its emissions. 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. ...
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.
And yes, that includes the amortized carbon "footprint" of the car manufacturing and food production processes.
Presumably this implies that walking across the country produces far more carbon dioxide than flying across the country.
(HT: Megan McArdle.)