Spanish emissions of carbon dioxide have grown by more than 40% in 2004 with respect to 1990. This is not compatible with the EU allocation of Kyoto-mandated CO2 reduction, even taking into account that Spanish emissions are allowed to rise by 15% in 2010. The reasons for this situation stem from a combination of economic growth and an inefficient energy domain, coupled with a total absence of climate change policies. In this paper, we use a static general equilibrium model to assess the effects of a sudden and intense (ie, with a limited time to carry out significant abatement) CO2 reduction by the Spanish economy. Our results show that the costs of immediate and medium-size reductions are not significant in the short run and could lead to the attaining of the EU agreed emissions level for Spain. However, delaying such action means that the degree of Spanish CO2 emission reduction is much higher and that economic costs are far more important.