2.3 International comparisons of carbon footprints

Carbon footprints are a relatively simple idea, but calculating them can be very complicated. It depends on whether you count only CO₂ or all GHGs and whether you include the emissions associated with imports and exports. It also depends on whether you include the emissions associated with changes in land use and forests, emissions from international aviation and shipping.

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, rather than the production- or consumption-based CO2e GHG emissions discussed earlier).