The Aircraft and Alternative Modes of Transport – Environmental Impact: Energy Consumption and Global Warming

The environmental impact of a means of transport is made up of energy consumption, global warming, changes in local air quality, noise and landscape consumption. Global warming in the transport sector is mainly due to the climate impact of CO2. The entire environmental impact of aircraft results from CO2, nitrogen oxides (NOx) and cloud formation due to contrails. This is summarized with the help of the equivalent CO2. Statistically speaking, the environmental impact can be greatly reduced, especially by flying lower. Contrails occur depending on altitude, air temperature, and humidity. Contrails are only persistent, if the relative humidity exceeds a certain value. It is the typical passenger aircraft with jet engines that cause contrails in cruise flight. Only a few of these contrails would have to be avoided in order to significantly reduce the environmental impact. Global warming caused by passenger jets is three times as high as CO2 alone. This is a significant environmental disadvantage of the aircraft compared to ground-based traffic. The selection of a means of transport can already be made according to basic physical principles. The wheel-rail system has a clear advantage here. However, aircraft are unrivalled, especially for quickly overcoming the oceans. Ways in which air travelers can reduce their environmental impact are presented. The "Ecolabel for Aircraft" evaluates aircraft in comparison. The "Karman-Gabrielli Diagram" considers also speed in a comparison of modes of transport.