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According to the Intergovernmental Panel on Climate Change (IPCC), there is a real danger that climate changes may be influenced by human intervention. Human intervention causes the composition of the atmosphere to change through the use of fossil fuels and other human activities, which have as a result the destabilization of the planet's thermal equilibrium, with major impacts on humans and the ecosystem.

In a series of IPCC Reports, the cooperating scientists argued, with incontrovertible scientific evidence, that the anthropogenic climate changes are speeding up and that there is a high a danger of more frequent extreme weather events, flooding, drought, etc. IPCC, through its representatives, has strongly been supporting since 1997 the immediate need to take corrective measures in order to prevent a global crisis resulting from anthropogenic interference with the climate system, which could seriously threaten the very existence of human life on our planet.

For its efforts to acquire and spread deeper knowledge of this problem and of the ways to deal with it, the IPCC was awarded, along with the US Vice President Al Gore, the Nobel Peace Prize 2007. The year 2007 also marks the 10th anniversary of the Kyoto Protocol.

Aircraft engines and greenhouse gases: their impact on the atmosphere


The report of IPCC "Aviation and the Global Atmosphere" was compiled in 1999 following a request from the International Civil Aviation Organization (ICAO) as well as from the partners of the Montreal Protocol on substances destroying the ozone layer in order to assess the impact on the atmosphere by greenhouse gases emitted by aircraft engines.

On this specific study, the level of knowledge was assessed concerning atmospheric science, aircraft technology and socio-economic parameters related to mitigation options of negative impacts in subsonic and supersonic aircraft fleets. Furthermore, the potential impact of aviation in the past and the future has been studied, as far as the reduction of the stratospheric ozone layer and the global climate change are concerned, although environmental impact issues at local level have not been addressed. The report composes the research findings in order to identify and characterize the options for limiting future impacts.

The professors of A.U.TH., Christos Zerefos and Alkiviadis Bais have participated as Review Editor and Lead Author correspondingly in Chapter 5 of the IPCC Aviation Report, on the issue of the impact of future aircrafts to the ultraviolet sunlight on the ground (Solar Ultraviolet Irradiance at the Ground). Following the analysis of calculations with radiation distribution models it was shown that aircraft emissions will bring a small decrease (<1%) to erythemal radiation levels on the ground by 2015, while for the year 2050 this reduction was estimated to be about twice as high. On the contrary, the introduction of supersonic aircrafts in the world fleet was estimated to result in a very slight increase (<1%) of erythemal radiation on the ground. These estimates are accompanied by considerable uncertainty which widens the range of estimated changes from -2% to + 3%. However, if we take into account the expected future changes in the stratospheric ozone (by the year 2050), then the impacts of future changes of the aircraft fleet to ultraviolet radiation on the ground are negligible.


School of Physics, Faculty of Sciences, Aristotle University of Thessaloniki

Ten years after their participation as Review Editor and Lead Author correspondingly on the Aviation Report of the IPCC, professors of A.U.TH, Christos Zerefos and Alkiviadis Bais received an honorary award in 2008, from the United Nations Environment Programme (UNEP) and the Intergovernmental Panel on Climate Change for their important contribution to the Intergovernmental Panel on Climate Change which was awarded along with the US Vice President Al Gore, the Nobel Peace Prize in 2007. Another 300 scientists worldwide received similar honorary awards for their contribution to the IPCC evaluation report on the Climate Change (IPCC Fourth Assessment Report: Climate Change 2007) and among them: Maria Kanakidou (Professor of University of Crete), Pantelis Kapros (Professor of Electrical and Computer Engineering, NTUA), Christos Giannakopoulos (researcher at the National Observatory of Athens) Sevastianos D. Mirasgedis (Researcher at National Observatory of Athens), Miltiadis Seferlis (Greek Biotope/ Wetland Centre) as well as Greek researchers of foreign institutions.

Professor Christos Zerefos has also been Review Editor of the 2012 IPCC Report: "Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, UK, and New York, NY, USA, 582 pp."

In 2015, Professor Christos Zerefos was awarded the Blaise Pascal Medal by the European Academy of Sciences as well as the Yoram J. Kaufman Unselfish Cooperation in Research Award by the American Geophysical Union.


Christos Zerefos, Emeritus professor of Atmospheric Physics of AUTH and Emeritus Professor of National and Kapodistrian University of Athens, Supervisor of Research Center for Atmospheric Physics and Climatology.

Alkiviadis Bais, Professor of Physics of Aristotle University of Thessaloniki, Head of the Laboratory of Atmospheric Physics (LAP), Physics Department, AUTH.