2.3 International comparisons of carbon footprints
You’ve seen that the carbon footprint is a simple idea, but calculating it can be complicated. It depends on whether you count only CO2 or all GHGs and whether you include the emissions embedded in imports and exports. It also depends on whether you include the emissions associated with changes in land use and forests and from international aviation and shipping which have not been mentioned until now.
This complexity means that international comparisons are usually based on the most widely available data, namely emissions of CO2 alone arising within a country’s borders (so-called territorial CO2 emissions).