The omnivore's confusion

An article in last week's Economist questions several widely-held assumptions about the environmental impact of different food choices and sourcing. If you've got 'em I'd be interested in seeing support or critiques of some of these ideas, especially the point about food-vehicle-miles and local products. Among the claims presented:

Organically grown food. The article quotes the "green revolution" guy, Norman Borlaug, who argues that the total land area required to produce a given amount of food organically is much greater than that required to produce it using synthetic fertilizers and pesticides. More land used for agriculture = more forest clearing etc. Borlaug, of course, has always been proponent of chemical agriculture, but the land area argument is new (to me at least).

Locally grown food. There are many reasons, social, economic, and environmental, to buy locally grown goods. One of the commonly accepted reasons is that locally grown food does not have to travel as far to reach your table, saving energy and pollution from transporting and preserving it. But the UK's environment and ag department recently put out a report that found that "a shift towards a local food system, and away from a supermarket-based food system, with its central distribution depots, lean supply chains and big, full trucks, might actually increase the number of food-vehicle miles being travelled locally, because things would move around in a larger number of smaller, less efficiently packed vehicles."

"Fair trade" food. Some economists don't like it because it messes with the price signals that should shift production away from crops that are being overproduced. (A problem if you assume that perfectly free markets always produce the "best" result.)