One of the arguments heard frequently from consumers who think that we should be buying our food locally is the environmental one, which claims that if food travels fewer miles to reach its consumer, then this results in fewer greenhouse gases being released into the atmosphere. One of the issues that Robert Paarlberg has with this argument in Food Politics is that food transport usually only makes up about 11% of the total greenhouse gases that are created to make a food product and ship it to us. Therefore, those who are interested in reducing the carbon footprint of the foods they eat should be more focused on how much energy is being used to make the food instead of how much is being used to transport it. James E. McWilliams calls this approach to eating sustainably the “hub and spoke system” in his book Just Food. The hub is in reference to finding the areas of the country or world where each type of food can be grown the most sustainably. For example, growing a vegetable in season and shipping it across the country might use less energy than growing it locally inside a greenhouse.

The other part of the hub and spoke system is the spoke, which references finding the most sustainable way to transport food to the consumer, even if it is over a long distance. When local food advocates talk about the environmental effects of transporting food long distances, Robert Paarlberg claims they also many times fail to realize that the load size of an amount of food being transported is just as important as the distance traveled. A local farmer transporting a small amount of vegetables for a short amount of distance in a pickup truck may be using more energy per food unit than a large amount of vegetables being transported for a large amount of distance in an eighteen wheeler.