In this paper we carry out a research of the CH4 emissions related to the Catalan agro-food sector through an alternative or at least complementary, input-output subsystems analysis, which is a useful tool to study the productive structure of the different sectors that make up an economy. The application of this technique allows the decomposition of the subsystem in different effects depending on the existing interindustry linkages with all the production sectors of the economy inside as well outside the subsystem. Results highlights the relevance of intrasectorial relations within the agro-food industry subsystem, which shows a significant autonomy respect to this type of emissions with regard to the rest of the economy. This feature guides the sort of environmental policies to be implemented in order to reduce the atmospheric impact of such activity