In an age where seasons no longer exist in grocery produce sections due to fast and relatively cheap transportation, it's extremely easy to overlook the environmental impact of that transportation. To combat this oversight, the sustainability community has created the concept of food miles, the amount of miles food travels from farm to store (and inherently the amount of greenhouse gases that travel generates).
Although it's not always a constant -- one famous study found that lamb shipped from New Zealand to England actually produced substantially less carbon dioxide than expected -- the fewer miles food travels the lower the impact it has on the environment [source: Chua].
Moving on the premise that consumers will make better choices if food miles aren't hidden, designer James Reynolds created FarFoods, a marketing campaign that includes functionality. The campaign is centered on produce labels that show how many miles a bag of clementines traveled, for example. The labels include bar codes and, when scanned, the food miles for each item appears by its price on the receipt and a total appears on the bottom.