Aviation and the Environment: Rating Airlines on Their CO2 Efficiency

The aviation industry contributes about 2% to the total global manmade CO2 emissions, which is seen as the main (manmade) greenhouse gas inducing climate change. This paper focuses on the design of a CO2 rating system which makes it possible to make a fair comparison of the environmental performance of airlines with respect to CO2 on the basis of public available data. It is argued that airlines can be best compared on the amount of CO2 emitted per revenue ton kilometer (CO2/ RTK) on the basis of distance sectors. Therefore, an airline is rated on various distance sectors. The CO2 efficiency scores of an airline within a distance sector can then be compared with other airlines. For nine airlines the CO2 efficiency is modeled, and the distance sector boundaries are determined. It is shown that the relative positions of airlines may change when choosing a different boundary, since the CO2 efficiency changes with distance. It is also shown that on the basis of public available information it is difficult to accurately determine the CO2/ RTK of an airline, which is due to lack of detail in public available data. A sensitivity analysis has been performed to show on which parameters information in greater detail is needed.