The Common Agricultural Policy, which is both dynamic and systemic, has aimed to adapt with its various Reforms to the environmental challenges faced by agriculture in Europe. The 2013 Reform brought the greenest CAP and, for the first time, Pillar 1 included measures that coexisted with, and complemented, those of Pillar 2. The purpose of this study is to determine which pillar is most effective in the fight against climate change because, even though the environmental effects of the CAP have been widely studied, there have not been sufficient studies in the literature that deal simultaneously with Pillars 1 and 2. We have drawn up an environmental equation for Spain, estimated using the Driscoll-Kraay technique which is the most suitable for panel data with cross-sectional and time dependence. The model shows that the best results were achieved with the second pillar, indicating that the adaptations and changes in environmental measures under the first pillar were not satisfactory for farmers and did not achieve their full potential.