Greenhouse gas emissions from air transport, and methods to calculate them, are not
well defined in the current literature. While calculating the direct emissions of CO2 is already cause
for some debate, the contribution of other emissions and impacts – like nitrogen oxides (NOx),
contrails, water vapour – to climate change still lacks a reliable metric. As aviation is the largest
emitter of greenhouse gases within tourism, accurate estimates of carbon and non-carbon emissions are important. This paper presents some standardisation as well as general insights to assist
researchers assessing the impact of aviation on climate change in scenario studies or evaluating
mitigation policies. The IPCC introduced a radiative forcing index (RFI) to measure the role of aviation in climate change, which is in scenario studies or evaluations of policies often used as a kind of
constant ‘equivalence factor’. The paper shows this to be inaccurate and proposes ways to account
for both carbon and non-carbon climate impacts of air transport