This paper considers the effect of international air-pollution agreements ratified since 1970 on carbon dioxide emissions (CO2), the main cause of anthropogenic climate change. The analysis is based on a panel dataset of 150 countries over the period 1970-2008. While the literature generally focuses on one particular agreement, we analyze the effect of the accumulation of agreements using a two-way (country, year) fixed effects regression model. We find that the relationship between the number of ratifications and CO2 emissions is statistically significant and linearly decreasing.