The consequences of climate change heavily influence the Mediterranean region. However, the Portuguese CO2 emission shows a decreasing tendency, the evolution of livestock and animal production have significantly increased its level in agriculture. The article investigates the role of the agricultural output and energy consumption in the environmental pollution in Portugal. It explores the short and long-run cointegration between carbon dioxide emissions and agricultural activities such as crop production, livestock production, and agricultural land use applying Autoregressive Distributed Lag (ARDL), Granger causality, Newey-West Standard Errors regression, as well as ARIMA model for the period of 1960-2015. The causality relation between CO2 emissions and agriculture is also analyzed. The Augmented Dickey-Fuller (ADF) unit root tests suggest that all variables are stationary. ARDL model demonstrates a long-run relationship between CO2 emissions, agriculture, and energy consumption. Results indicate that agricultural activities and energy use have a positive effect on environmental pollution; therefore, the Portuguese agriculture needs to achieve a higher level of sustainable development, with reducing the impact of animal husbandry and intensive crop production.