"Just because you bought your chicken from a local farm, that doesn't mean it has less impact than a chicken from the local grocery store, which may have been shipped from thousands of miles away. It all depends on how that chicken was produced."In the article is something I've been looking for: a collective look at carbon impact of various foods. Instead of trying to show the impact of what's on your plate, this graph shows the total for all US food usage. It turns out that transport is the least significant part of the picture:
The author's conclusion about local foods: they aren't necessarily the only solution to global problems. He says:
"With a majority of our citizens living in cities, local agricultural production – from hydroponic greenhouses to small urban vegetable gardens – can help address the growing demand for nutrients and fresh produce in urban areas, and become key strategies to reduce overall food waste. However, it will be very difficult to produce our daily calories in cities, specifically bulk calorie crops such as cereal grains, roots and tubers, sugar and bananas that today still need to be produced where vast areas of land are available for cultivation."