Spatial consumption-based carbon footprints: two definitions, two different outcomes

The spatial consumption-based assessment tradition is already 30 years old. However, while all the well over 100 studies in this field over the past 30 years have been published under the same consumption-based carbon footprint label, the studies actually fall into two main categories, which have substantial differences between them, by definition in what they include, and how they allocate the emissions. The first utilizes the territory principle and the other the residence principle, meaning that it is partly different consumption activities that are included in the two. The territory principle means that consumption activities are included based on where consumption takes place regardless of who the consumers are, whereas the residence principle means that all consumption of the residents is included regardless of where they consume. Overall, the two lead to potentially very different estimates, and fit to different study situations. So far, this important issue has gone without much attention. In this paper we provide in-depth discussion, through a theoretic example, on how the scopes and the allocation principles vary between the two approaches, and on how the approach choice affects the outcome of an assessment. The provided discussion shows how profoundly different the two approaches can be, and emphasizes the importance of being clear in communicating the allocation principle in every spatial consumption-based study. One approach is not superior to another, but instead they show different perspectives, and the practitioner should carefully select the approach with a better fit with the aim of the study in question.