Abstract The growing offshoring process is the result of the fragmentation of production processes and the creation of global supply chains. This process has increased final and intermediate imports, but also the distance that goods travel in different stages until they reach the final consumer, as well as the requirements of transport per unit of output and the volume of CO2 emissions generated in transporting them. Nowadays, there is no generally accepted criterion for international transport pollution allocation. No single country has the responsibility for emissions of international bunkers provided by IPCC. In this paper we propose a new methodology for quantifying by sector the impact of international freight transport on total pollution and assigning responsibility to consumers. This methodology considers the distance and the means of transport as key elements and uses input–output methodology. We apply this to the Spanish economy combining data from input–output tables, import data, and CO2 emission data. The results show that the proportion of total CO2 emissions accounted for by emissions from international freight transportation, allocated via the consumer criterion, increase up to 4.16% between 1995 and 2000. As expected, the industries where this offshoring process is more intense show the greatest increases in carbon emissions related to international transport. These emissions are significantly higher than emissions embodied in domestic inputs in some of those industries where international fragmentation of production is relevant and increasing.