Science tells us that aviation accounts for about 5% of global greenhouse gas (GHG) emissions because of the CO2 that is  emitted when jet fuel is burned. But aviation not only causes global warming through CO2 emissions, other factors, such as  contrails and cirrus clouds also lead to significant warming (see: www.co2offsetresearch.org/aviation/
AviationImpacts.html). If all these factors are taken into account, aviation may  currently be responsible for up to 14% of man-made climate change (Lee et al., 2009).

The GHG emissions from aviation are growing rapidly at about 4% annually (Solomon et al., 2007). Globally, CO2 emissions from aviation almost doubled from 1990 to 2006. In the absence of policies to control, emissions from aviation could grow by 300-400% by 2050.

The climate impacts from air travel are caused by only 2% of the world population that actively takes part in air travel.

To learn more download this Policy Brief which includes contributions by Carbon Market Watch.