This paper aims to study the symmetric and asymmetric effects of financial globalization on CO2 emissions in the MENA region. Using a panel dataset of seven non-OPEC MENA countries over the period 1980-2014, we perform a comprehensive econometric analysis based on the panel ARDL and non-linear panel ARDL (NARDL) models and a battery of tests, including cross-sectional dependence tests, second-generation unit root tests and cointegration tests. The findings reveal a significant long-term impact of financial globalization on CO2 emissions that can be symmetric or asymmetric depending on the nature of financial globalization. While external debt liabilities appear to be polluting because they increase CO2 emissions significantly and linearly, the long-term impact of FDI and portfolio investment liabilities on CO2 emissions is asymmetric, with only negative shocks of FDI and portfolio investment decreasing CO2 emissions. This suggests that financial globalization through foreign investment (FDI and portfolio investment) is more environmentally friendly than financial globalization through debt, which provides interesting insights for policy makers.