Air traffic

Climate protection in air traffic is now seen as an important social issue.

• An overseas flight increases one's personal CO2 footprint considerably. It can amount to a third of the yearly CO2- emissions of the average Swiss person (between 7 to 10 tons). A return flight from Zurich to New York for instance will create almost 3 tons of CO2.

• Air traffic is showing strong growth. With a growth rate of 6 percent per annum, air traffic is increasing faster than any other transport sector. Forecasts predict that this growth rate will stay relatively steady for the next 10 to 15 years.

As is the case for all other sectors causing greenhouse gases, there will need to be considerable efforts to reduce greenhouse gas emissions in the air traffic sector in the immediate future.

Impact on the climate through air traffic

The amount of greenhouse gases emitted during a flight is dependent on two main factors: The amount of fuel burned, and the engine type.

The amount of fuel burned depends on the distance travelled, flight altitude, weather conditions, aerodynamics and the weight loaded. A precise calculation per flight is therefore extremely complicated and not practical. In practice, average values are therefore used to calculate emissions for flights.

Normally the emissions of greenhouse gases per passenger and 100 kilometres are calculated ("100 passenger kilometres"). The emission of CO2 per 100 passenger kilometres is between around 11.6 kg (long haul flights) and 26.2 kg (short haul flights) (Source: ecoinvent). Aside from CO2 , air traffic causes numerous further climate-impacting emissions. Therefore the total impact of air traffic on global warming is higher than that of the effect of the CO2 emissions alone by a factor of around to 2 to 4. In order to take these other climate-impacting air traffic emissions into account, the myclimate flight calculator multiplies the pure CO2 emissions by a factor of 2.

Short vs. long haul flights

The shorter the flight distance, the higher the specific kerosene consumption. The reason for this is to be found in the relatively high consumption in the start phase, which for short flights is a greater proportion of the journey. This explains why in a modern A320 fleet (short and medium haul flights) around 5.3 litres of kerosene are used per passenger and 100 km, while the figure is around 3.2 litres in an A330/340 fleet (long haul). Kerosene consumption is lower during cruise flight. A further factor that governs consumption is plane size. Smaller planes are used for short and medium-haul flights, and these can carry fewer passengers. They therefore use more kerosene per passenger than large planes. However, the total consumption, and therefore climate impact, is of course higher on long-haul flights.

Solutions and strategies

On the one hand, air traffic has the great advantage of being able to transport people and goods across large distances in a very short time, making it an essential part of our economy. On the other hand, it has the disadvantage of a very high energy consumption and therefore a big impact on the climate. Solutions and strategies to avoid or mitigate these disadvantages must be found.

The airline industry is tackling this challenge in various ways:

• economic instruments (e.g. emissions trading and voluntary CO2 offsetting),
• technological progress (e.g. low-emissions turbines and lighter planes),
• operational measures (e.g. more direct flight routes, fuel-saving take-off and landing procedures),
• more efficient infrastructure (e.g. better utilisation of the air space and airports)

Other approaches to solutions cover ideas like the replacement of business flights with video conferences, demand control through taxation or voluntary agreements.