Public knowledge about the differences in greenhouse gas emissions caused by the production and transportation of different kinds of food are generally low. People with an interest in choosing food with low greenhouse gas emissions must therefore either increase this "food carbon literacy" or be provided with such information when they decide what food to buy. Research about this specific kind of food literacy is, however, scarce, lacking both well-defined terminology and interventions attempting to increase food carbon literacy. In this paper we provide a framework for future research in the area by defining "food carbon literacy", serving as a starting point for categorizing, comparing, and generalizing future research findings. Drawing on previous work on other kinds of literacies, we distinguish between (1) food carbon literacy, (2) food product carbon literacy, (3) food handling carbon literacy, and (4) financial food carbon literacy. We have furthermore developed and tested a digital behavior change intervention in the form of a digital grocery list used on mobile phones. The list works as other digital grocery shopping lists, but also displays the CO(2)e footprint of the food added to the list, thereby enabling the user to change products at the planning stage and increase their food carbon literacy. It was tested on a group of 38 people for a duration of 2 weeks. The goals of the pilot study were to investigate quantitatively whether such a tool would increase food carbon literacy, and to investigate qualitatively how such a tool could be used and designed. The results show a strong increase in food carbon literacy for food the respondents had added to their grocery lists, but also for food that had not been added to their lists, indicating a generalization of the knowledge. Finally, we provide implications for the design of such systems, based on the qualitative evaluation.