This report assesses the effects of aircraft on climate and atmospheric ozone and is the first IPCC report for a specific industrial subsector. It was prepared by IPCC in collaboration with the Scientific Assessment Panel to the Montreal Protocol on Substances that Deplete the Ozone Layer, in response to a request by the International Civil Aviation Organization (ICAO) because of the potential impact of aviation emissions. These are the predominant anthropogenic emissions deposited directly into the upper troposphere and lower stratosphere. Aviation has experienced rapid expansion as the world economy has grown. Passenger traffic (expressed as revenue passenger kilometers) has grown since 1960 at nearly 9% per year, 2.4 times the average Gross Domestic Product (GDP) growth rate. Freight traffic, approximately 80% of which is carried by passenger airplanes, has also grown over the same time period. The rate of growth of passenger traffic has slowed to about 5% in 1997 as the industry is maturing. Total aviation emissions have increased, because increased demand for air transport has outpaced the reductions in specific emissions3 from the continuing improvements in technology and operational procedures. Passenger traffic, assuming unconstrained demand, is projected to grow at rates in excess of GDP for the period assessed in this report. The effects of current aviation and of a range of unconstrained growth projections for aviation (which include passenger, freight, and military) are examined in this report, including the possible effects of a fleet of second generation, commercial supersonic aircraft. The report also describes current aircraft technology, operating procedures, and options for mitigating aviation's future impact on the global atmosphere. The report does not consider the local environmental effects of aircraft engine emissions or any of the indirect environmental effects of aviation operations such as energy usage by ground transportation at airports. Comments Reprinted from Aviation and the Global Atmosphere, Intergovernmental Panel on Climate Change, edited by J.E. Penner, D.H. Lister, D.J. Griggs, et al., (Cambridge: Cambridge University Press, 1999), pages 1-12. NOTE: At the time of publication, the author Anu Vedantham was affiliated with the U.S. Department of Commerce. Currently, she is the Director of the Weigle Information Commons at the UPenn Libraries of the University of Pennsylvania. This government publication is available at ScholarlyCommons: http://repository.upenn.edu/library_papers/58 SUMMARY FOR POLICYMAKERS AVIATION AND THE GLOBAL ATMOSPHERE A Special Report ofWorking Groups I and III of the Intergovernmental Panel on Climate Change This summary, approved in detail at a joint session of IPCC Working Groups I and III (San Jose, Costa Rica· 12-14 April 1999), represents the formally agreed statement of the IPCC concerning current understanding of aviation and the global atmosphere. Based on a draft prepared by: David H. Lister, Joyce E. Penner, David J. Griggs, John T. Houghton, Daniel L. Albritton, John Begin, Gerard Bekebrede, John Crayston, Ogunlade Davidson, Richard G. Derwent, David 1. Dokken, Julie Ellis, David W. Fahey, John E. Frederick, Randall Friedl, Neil Harris, Stephen C. Henderson, John F. Hennigan, Ivar Isaksen, Charles H. Jackman, Jerry Lewis, Mack McFarland, Bert Metz, John Montgomery, Richard W. Niedzwiecki, Michael Prather, Keith R. Ryan, Nelson Sabogal, Robert Sausen, Ulrich Schumann, Hugh J. Somerville, N. Sundararaman, Ding Yihui, Upali K. Wickrama, Howard L. Wesoky