Tesco, Britain’s largest retailer, is working to develop a system of carbon labels for each of their 70,000 products. You might assume that you can easily calculate the carbon footprint of your favorite item by analyzing how far it might have traveled to land in your basket, but to really determine the carbon footprint you need to go further.
For example, if you live in New York, it would create less carbon emissions to drink Bordeaux instead of Californian wine. Although your Bordeaux is traveling from a further distance, it comes by boat, which creates less carbon output than the California wine which travels by truck.
For more information, check out Terri Gross' interview with Micheal Specter, a New Yorker Journalist who explains the idea of putting carbon footprint labels on our food. For a great article on the subject, read his story in the New Yorker, "Big Foot: In Measuring Carbon Emissions, it's Easy to Confuse Morality and Science".