Aviation causing 4.9% of man's climate change impact?

Among the papers presented at ICAO's fourth GIACC meeting held in Montreal on 25-27 May 2009 was one by the International Coalition for Sustainable Aviation (co-ordinated by the European Federation for Transport and Environment). At the back of this information paper is an abstract of a scientific journal article currently in press, Aviation and Global Climate Change in the 21st Century by Lee, Fahey, Forster, Newton, Wit, Lim, Owen and Sausen.

The abstract of the new scientific paper suggests that in 2005 the figure for aviation was around 3.5% of total anthropogenic forcing or, if aviation-induced cirrus cloud formation is taken into account, around 4.9% but there is not a high degree of confidence in the latter number.

The formation of cirrus cloud by aviation activity is more common in parts of the northern hemisphere where the bulk of aviation activity occurs.

Note that the abstract states that in the period 2000-2005 total air traffic increased by 22.5% while total aviation fuel use went up by 8.4%. The total increase in aviation-induced radiative forcing over the same period was estimated to be 14%, excluding the cirrus cloud formation.

To date one of the most widely quoted sources on aviation's impact has been the IPCC's 1999 Report Aviation and the Global Atmosphere.