How is the atmosfair offsetting contribution calculated?

For this, there are two components that come together: firstly the CO₂ emissions of a flight and secondly the costs of saving this amount in a climate protection project.

The CO₂ emissions of a flight are calculated using the atmosfair emissions calculator. With this, other pollutants like nitrogen oxide or soot particles besides pure CO₂ emissions are also included that warm the climate in addition to CO₂. For this reason, the values for a flight with atmosfair are higher than with most other emissions calculators.

The emissions calculator sets a price of 23 euros per tonne of carbon dioxide. These 23 euros are currently needed in order to save a tonne of CO₂ in high-quality climate protection projects in developing countries. An example can illustrate how the price of saving a tonne of CO₂ comes into being:

On the roofs in an outer settlement of Cape Town in South Africa, all warm water is normally heated using diesel cookers. This is emissions-intensive and moreover expensive. atmosfair arranges the installation of solar panels with a project operator in South Africa; these panels are mounted onto house roofs and heat the water directly. To implement the 50 installations, the operator receives the 23,000 € required from atmosfair. In the ten years of the contractual term, 40,000 litres of diesel will be saved each year and thus the climate will be saved 1,000 tonnes of carbon dioxide (CO₂) in total. Thus, in this project, atmosfair can save 1,000 tonnes of CO₂ with 23,000 €. atmosfair concludes a contract with the project operator, after which the operator receives 23 € from atmosfair for a demonstrably saved tonne of CO₂, and pays the first 15,000 € as an advance payment so that the project operator can begin. A UN-accredited auditor who is liable for any mistakes must complete the verification of the successful  CO₂ reduction.

The principle of saving emissions caused somewhere else underlies the economic insight that it is less expensive to avoid damage than to repair it. In other words, once a storm destroys a settlement the costs for rebuilding it are higher than the costs of climate gas avoidance that would not have allowed the storm to arise in the first place. Thus, the emissions contribution of a long-distance flight does not reflect the costs for the “repair” of the damage caused to the climate, but rather the amount that is required to avoid these emissions somewhere else.

Why do even the shortest flights always cost at least 5 euros?

atmosfair sets a minimum price for all flights of 5 euros for one-way flights and 10 euros for roundtrip flights so that the topic “air traffic and climate” will be taken seriously.

A smaller contribution would suggest that short-distance flights are unproblematic for the environment. However, this is not the case because even a flight from Berlin to Munich and back creates 300 kg CO2 per passenger. This is already the equivalent of three times the yearly usage of a refrigerator or one-seventh the yearly environmentally sound annual climate budget for one person.

In addition, flights covering short distances are those that are the easiest to replace with a train journey. If we stay with the example from above: if you cover the route from Berlin to Munich with an ICE train, you create just a fifth (around 60 kg) of the incidental flight emissions over the round-trip journey!

Why does the emissions calculator only make its calculations using carbon dioxide? Airplanes also emit other pollutants that harm the climate.

Carbon dioxide, nitrogen oxide, soot and sulphur particles as well as water vapour from aircraft engines affect the climate with different durations and intensities. But because all of these together add to the layers of greenhouse gases in the atmosphere, atmosfair calculates them approximately in terms of carbon dioxide.

In sum, the different emissions in high flight altitudes of more than nine kilometres have an effect that is about three times as strong as the carbon dioxide of a flight.

In order to appropriately represent the climate impact of all flight emissions, the atmosfair emissions calculator multiplies the CO2 emissions emitted at altitudes over 9 km with the global average multiplicator of 3. This multiplicator results when the global warming potential of all non-CO2 effects is integrated and discounted over 100 years (UNFCC) and (David Lee et al., “Transport impacts on atmosphere and climate: Aviation”, in atmospheric environment (44), 2010).

Do short-distance flights cause more emissions than long-­distance flights?

Basically, it’s the case that the longer the flight is, the more detrimental its impact on the climate. This is because for each additional kilometre flown, more fuel is used and thus more greenhouse gases are emitted. However, if we consider the relative consumption per 100 kilometres of the flight route, this relationship changes.

On the one hand, aircrafts fly along short-distance routes up to around 400-600 kilometres in low atmospheric altitudes, in which no contrails or ice clouds are created. The ozone formation from nitrogen oxide is less here than in altitudes above around 9 kilometres. Finally, the kerosene tanks of an aircraft that must only cover 500 kilometres are much lighter than those of one that will cover a long-distance flight. On the other hand, the kerosene-intensive ascent of a short-distance flight carries much more weight than it does on an intercontinental flight.

You can find detailed information on the topic “distances” in the atmosfair emissions calculator documentation.

Is it important whether I fly on a scheduled or a charter flight?

On a charter aircraft, more passengers typically fly than in a scheduled plane of the same size. Due to the higher utilisation of the charter plane, a person travelling on a packaged tour has less of an impact on the climate than an individual traveller.

You can find detailed information on the topic “capacity utilisation” in the atmosfair emissions calculator documentation.

Why can one enter either business or economy class? Does that make a difference?

The seats are wider in business class. As a result, fewer people can be seated in the same amount of space as in economy class. Because the fuel consumption per person decreases when more people can be seated in an aircraft, the atmosfair contribution for a seat in business class is higher on average than the emissions contribution for a seat in economy class. As a consequence, passengers in economy class donate somewhat less and passengers in business somewhat more than average.

You can find detailed information on the topic “flight class” in the atmosfair emissions calculator documentation.

Do I need to know the aircraft model?

The more precise the flight data that you enter into the emissions calculator are, the more exactly the resulting per person emissions can be calculated. However, if you do not know the aircraft model, the emissions contribution can still be calculated using atmosfair’s approximated values. The calculator knows all the aircraft models that fly on a given route and forms an average value from these. Naturally, entering the aircraft model makes the calculation more exact. The emissions calculator has all consumption data of all commercial aircrafts saved, so it captures most civil air transport. Because only certain models are used on each route, the emissions calculator compiles a virtual average aircraft that is typical for the connection at hand.

You can find detailed information on the topic “aircraft type” in the atmosfair emissions calculator documentation.


How exact are the results of the emissions calculator?

It is clear that only the likely climate gas emissions of a flight can be calculated. If the aircraft must circle due to icy runways or if the occupancy is exceptionally high or low, the calculator cannot take this into account. In this respect, the emissions calculator’s results cannot be as exact as directly measuring the emissions on-site. However, in general, its results should correspond well with reality due to the range and quality of the underlying data.

You can find a discussion of the methods and the accuracy of results in the atmosfair emissions calculator documentation.