The impact of air travel on climate change is multifaceted. Aircraft burn large amounts of fuel and emit greenhouse gases. Another problem has to do with where these emissions end up. Planes fly at altitudes where the air is thin and the chemistry is both complex and fragile.
Aircraft emissions have a warming effect that is 1.9 times that of carbon dioxide alone. The key greenhouse gases and emitted by aircraft are Carbon dioxide (CO2), Nitrogen oxides (NOx) and water vapour.
A plane traveling from North America to London and back generates about 1.4 tonnes of CO2, that is the equivalent of more than 3 months of driving. Nitrogen oxides produced by air travel increases ozone concentrations in the upper troposphere which warms the planet more than it would at lower altitudes. When water vapor it is released in the stratosphere (above 10,000 metres) it builds up and creates contrails and cirrus clouds that warm the Earth’s surface, especially at night. Soot aerosols emitted by planes also warm the Earth because aerosols also influence the formation of clouds.
Air travel has increased substantially in the last few decades. In 1992, it accounted for just 2 percent of anthropogenic carbon dioxide emissions (13% of CO2 from all transportation sources). Between 1985 and 2000 passenger air traffic has doubled and air cargo traffic has grown even more quickly. In 2006, Boeing and Airbus forecasted that passenger air travel and air cargo would triple the 2004 level before 2020. According to their forecasts this translates to 22,700 new passenger and freighter aircraft by 2026.
Source: Climate Change Connection
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