There is scientific consensus that aviation contributes to climate change in three ways

• Combustion of fuel emitting carbon dioxide
• Contrails in the atmosphere generated at specific atmospheric conditions
• Emissions of nitrogen oxides at high altitudes which, through chemical reactions, influence the levels of methane and ozone

All these three atmospheric factors influence the heat radiation from the earth. According to the majority of the research community, two-thirds of aviation’s climate impact comes from non-carbon dioxide-based emissions.

For each individual flight, running on fossil fuels generate a certain amount of carbon dioxide emissions can be assessed with its climate impact.

The emissions of nitrogen oxides can also be quantified relatively well, but their effect depends on specific atmospheric conditions and chemical reactions.

The formation of contrails depends on the amount of water vapor that is formed and specific atmospheric conditions. Contrails are relatively short-lived.

Calculating the total climate impact of aviation in addition to carbon dioxide on the basis of carbon dioxide emissions is not correct. It should rather be based on:

– Nox emissions with factor for chemical reaction with impact on ozone and methane content

– Water discharge with factor for conditions for the formation of contrails

For the time being, NTM has chosen not to apply a standardized calculation of the flight’s climate impact based on a multiplicator on carbon dioxide emissions as the underlying assessments are too uncertain, especially for individual flights. However, NTM is conducting development to better describe the entire climate impact of aviation in NTMCalc.

NTM does not evaluate whether other actors, on the basis of emissions of carbon dioxide calculated in NTMCalc make a calculation of total climate impact, but does not want to be held responsible for these calculations and assumptions.