6 April 2011
A paper coauthored by CSD scientist David W. Fahey has been honored as one of the top 50 most-cited papers in the last 5 years (January 2006 to February 2011) in the journal Atmospheric Environment.
The paper, Aviation and global climate change in the 21st century was published in July 2009 and so achieved this distinction in about 1.5 years.
The authors undertook the study because new data indicated higher aviation activity in recent years (2000-2005) than had been assumed in the most recent IPCC studies regarding aviation and climate. The paper re-examined the aviation impacts in light of the new data, assessed uncertainties, provided some new illustrative scenarios of future aviation emissions, and examined potential mitigation opportunities afforded by technological improvements and policy measures.
David S. Leea, David W. Faheyb, Piers M. Forsterc, Peter J. Newtond, Ron C.N. Wite, Ling L. Lima, Bethan Owena, and Robert Sausenf, Aviation and global climate change in the 21st century, Atmospheric Environment, doi:10.1016/j.atmosenv.2009.04.024, 2009.
Aviation emissions contribute to the radiative forcing (RF) of climate. Of importance are emissions of carbon dioxide (CO2), nitrogen oxides (NOx), aerosols and their precursors (soot and sulphate), and increased cloudiness in the form of persistent linear contrails and induced-cirrus cloudiness. The recent Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) quantified aviation's RF contribution for 2005 based upon 2000 operations data. Aviation has grown strongly over the past years, despite world-changing events in the early 2000s; the average annual passenger traffic growth rate was 5.3% yr-1 between 2000 and 2007, resulting in an increase of passenger traffic of 38%. Presented here are updated values of aviation RF for 2005 based upon new operations data that show an increase in traffic of 22.5%, fuel use of 8.4% and total aviation RF of 14% (excluding induced-cirrus enhancement) over the period 2000-2005. The lack of physical process models and adequate observational data for aviation-induced cirrus effects limit confidence in quantifying their RF contribution. Total aviation RF (excluding induced cirrus) in 2005 was ~55mWm-2 (23-87 mWm-2, 90% likelihood range), which was 3.5% (range 1.3-10%, 90% likelihood range) of total anthropogenic forcing. Including estimates for aviation-induced cirrus RF increases the total aviation RF in 2005-78 mWm-2 (38-139 mWm-2, 90% likelihood range), which represents 4.9% of total anthropogenic forcing (2-14%, 90% likelihood range). Future scenarios of aviation emissions for 2050 that are consistent with IPCC SRES A1 and B2 scenario assumptions have been presented that show an increase of fuel usage by factors of 2.7-3.9 over 2000. Simplified calculations of total aviation RF in 2050 indicate increases by factors of 3.0-4.0 over the 2000 value, representing 4-4.7% of total RF (excluding induced cirrus). An examination of a range of future technological options shows that substantive reductions in aviation fuel usage are possible only with the introduction of radical technologies. Incorporation of aviation into an emissions trading system offers the potential for overall (i.e., beyond the aviation sector) CO2 emissions reductions. Proposals exist for introduction of such a system at a European level, but no agreement has been reached at a global level.