Factors affecting aircraft CO2 emissions

Since the actual fuel used provides the most accurate and direct link to CO2 emissions, fuel consumption is a crucial element when calculating CO2 emissions. However, the fuel consumption is affected in many ways. Weight is certainly the primary driver for an aircraft's fuel consumption. Other important factors include the type of aircraft, whether it is a short or long-haul flight, weather patterns (tail wind or head wind) and various operational impacts such as holding patterns and derouting due to inefficient air traffic control. A continuous descent approach could reduce fuel consumption, however, fragmented European airspace make this impossible. While more weight of the cargo on a plane increases fuel consumption it reduces the relative fuel consumption per tkm making the transport operation more efficient.

It is therefore a real challenge to calculate the CO2 emissions from third party air freight accurately. In theory, the most precise approach would be to evaluate on a flight by flight level the actual fuel consumption and the total amount of payload on that flight. Unfortunately, this data is not readily available to companies other than the airlines themselves.

Examples of technology improvements

Despite the fact that air freight has by far the highest CO2 emissions per tonne kilometre, there have been substantial energy efficiency improvements over the last decades and there are potentials to further reduce the fuel consumption significantly.