Seventeen percent of this nation’s petroleum consumption is dedicated to on-the-farm food production. Add on processing, packaging, refrigeration and transport of edibles and food takes a big bite out of affordable oil supplies and contributes to pollution. Domestic food as basic as lettuce we could grow in front yards most of the year, and green houses in winter, travels up to 3,000 miles from field to table.
http://www.lifecyclesproject.ca/initiatives/food_miles/calculating_food_miles.php explains how this takes into effect greenhouse emissions.
Sustainable Table: Buy Local: http://www.sustainabletable.org/issues/buylocal/
Do food miles matter? | ES&T Online News: http://www.nrdc.org/health/foodmiles/