We describe the current status of knowledge regarding the contribution of aviation to anthropogenic climate forcing. The emissions and associated radiative forcings from aviation are compared to those from other modes of transport. The different analytical metrics used to quantify climate forcing are presented showing their relevancies and uncertainties. The discussion then focuses on the use of radiative forcing, one of the most commonly used metric, in accounting for the climate change contribution from aviation with a particular look at how the contribution from CO2 and non-CO2 greenhouse gases can be compared.O. Dessens acknowledges funding from QUANTIFY (European Union 6th Framework Program under contract number 003893)
