This paper analyzes the relation between economic performance and CO2 emissions in Brazil, in the year 2004. The contribution of the productive sectors to total emission is established, taking into account the technological structure of the economy, the interrelations among sectors, the sectoral capacity of generating value-added and the participation of final demand in the national sectors. For this purpose, an input-output model is used to analyze the impact of income generation and final demand on the emissions. This approach allows one to study the impacts caused by sectoral mitigation policies. The main results show that, both from a production and a demand perspective, the same key productive sectors stand out, especially the Transport sector.