Apparently walking to the shops is worse for the environment, in terms of greenhouse emissions, than driving (see article here). The authors of the study attribute this to the massive amounts of energy that go into modern day food production, making human energy expenditure less efficient than for automobiles.
wouldnt this depend on the manner and level of food consumption? I can see how the current status quo might yield such a result, but the thesis wouldnt neccesarily hold for a more locally based ( and perhaps internationally networked) form of food production.
Absolutely. If I remember correctly the author of the article specifically analyzes Western style agriculture to arrive at his conclusions. No doubt they would differ significantly if the agricultural model changed.