Locavorism, the idea that eating locally-sourced food is inherently virtuous and environmentally responsible, has become increasingly popular as a “food philosophy”. The standard argument in support of locavorism is that shipping industrially-produced food half way around the world so we can have tomatoes in January is a waste of resources and a threat to the environment. We should instead eat only food grown locally and in season, in order to reduce our carbon footprint.
I don’t normally take libertarian arguments too seriously but this article by Pierre Desroches and Hiroku Shimizu does a pretty good job of debunking the concept of food miles and its impact on the environment. Their main point is that long distance, sea transport uses less energy per unit of food than even a short car trip.
They go on to claim that the promotion of local food is dangerous and is ” a marketing fad that frequently and severely distorts the environmental impacts of agricultural production”.
Of course “food miles” is not the only issue with regard to industrial agriculture. But the linked article is correct that it is too simplistic to think eating locally will do much to save the planet. Furthermore, in many parts of the world, including the U.S., there isn’t enough food for everyone to eat only locally.
Nevertheless, eating locally can be defended on other grounds. Locally grown food is usually fresher, safer, more nutritious, it tastes better, and it is good for the community as a whole to support local businesses.
Locavorism is not a panacea for solving the problems of industrial agriculture. It is just a good way of enjoying fresh food if you can take advantage of it.
Exploring the Philosophy of Food and Wine 
Just wanted to mention, as a supplementary resource containing similar arguments, that a nice critical discussion of the energy-based arg for locavorism occurs at around p148ff of Singer and Mason, _The way we eat: why our food choices matter_ (Rodale, 2006; strangely, the same book is also published under the title _The Ethics of What We Eat_ — with at least two different covers — by Text Publishing Company). Singer and Mason go on to raise further concerns with standard motivations for locavorism, including a utilitarian-based criticism of the oft-invoked claim that the practice financially supports one’s local community (roughly: you typically buy a lot more utils with your dollar if you spend it in non-local places where the people are much more impoverished).