"Shipping activities also lead to significant emissions of greenhouse gases and air pollutants, noise and water pollution. Carbon dioxide emissions from global shipping could be 17% of all carbon dioxide emissions by 2050 if no further action is taken. While emissions of some pollutants from road transport have gone down in general (although not carbon dioxide), emissions from aviation and shipping continue to rise. By 2050, global aviation and shipping are together expected to contribute almost 40% of global carbon dioxide emissions unless further mitigation actions are taken."