Climate impact of aviation is caused by both CO2 emissions and non-CO2 effects, comprising by way of example contrail and contrail-cirrus, as well as nitrogen oxide (NOx)-induced ozone (O3) formation and methane (CH4) destruction. Aviation can mitigate its climate impact by reducing CO2 emissions and also by reducing non-CO2 effects. One option to implement such mitigation strategies is to avoid regions of the atmosphere which are in particular sensitive to non-CO2 effects, by identifying alternative, climate-optimized aircraft flight paths.
Within the frame of European collaborative research projects under the coordination of the DLR Institute of Atmospheric Physics in Oberpfaffenhofen, the initial idea of avoiding climate sensitive regions in the atmosphere was developed in the European Aeronautic collaborative project REACT4C. This idea was taken further in the SESAR JU (Single European Sky Aeronautics Research Joint Undertaking) projects ATM4E and FlyATM4E and climate mitigation potentials were explored for the European air space (Matthes et al., 2020), in order to develop strategies on how to identify such climate optimal flight paths and to explore concepts on future implementation in an advanced air traffic management.
“Central elements of such climate-optimized flight planning is the provision of temporally and spatially resolved information, where these climate sensitive regions are located and the provision and quantification of the climate impact of aviation emissions, which are deposited at these specific locations”, explains project leader Dr. Sigrun Matthes, atmospheric scientist in the Earth-System Development department of the DLR Institute. “For this we have developed in our team the concept of the climate change functions, which enable to provide information on these climate sensitive regions as a meteorological (MET) service to the flight planning process”. Her work in the current research project FlyATM4E (Flying Air Traffic Management for Environment) is mentioned on the occasion of the international women’s day presenting her work as project leader together with other European Initiatives in a SESAR article (Women in ATM).
Cumulative CO2 emission distribution from 1-day-case-study for the European Airspace as geographical distribution and vertical distribution (bottom and right). (Source: Lührs et al., 2021)
In a case study for the European Airspace it was shown in the Exploratory Research SESAR Project ATM4E that considerable mitigation potentials exist by using a first estimate of these climate change functions on a day with high contrail formation, with only small fuel penalties when avoiding that region. These mitigation potentials are caused by a reduction of non-CO2 effects, in this case especially contrails (Matthes et al., 2020). For such an optimization it was shown, that by efficient selection of flight paths and only optimizing 25% of the city pair connections considerable mitigation gains can be achieved (Lührs et al.,2021).
Both scientific articles are part of the special issue “Towards Sustainable Aviation”, presenting contributions to the ECATS Conference on the challenges of sustainable aviation in the journal Aerospace. Other interesting studies explore e.g. future engine concepts, on the mitigation potential of formation flight, on prediction of contrail formation, or how the climate impact changes when aircraft are flying at alternative flight altitudes. This scientific conference is regularly organized by the international association ECATS (Environmentally Compatible Air Transport System, IASBL, Brussels), and this 3rd conference was successfully held as an online event. The association founded in 2010 includes members of leading research institutions and universities in Europe in the domain “Aviation and Environment” and is organizing, with currently Dr. Sigrun Matthes acting as chair, its work in several working groups. Topics are e.g. alternative aviation fuels, climate impact of aviation and mitigation options, and green flight, disseminated and supported by conferences, scientific project collaboration, and student schools to foster the education of early career scientists.
The FlyATM4E consortium, led by the DLR Institute of Atmospheric Physics, is composed of Technical University Hamburg, Technical University Delft, University Carlos III in Madrid, DLR Air Transport System and it builds on its expertise covering the whole spectrum from atmospheric science and climate research to aviation operations research and aircraft trajectory optimization.
Contrail and contrail-cirrus affect radiative balance of the Earth and have predominantly a warming effect. (Photo: © Sigrun Matthes)
Women in aviation: An untapped resource, SESAR Joint Undertaking, 8 May 2021.
Matthes, S.; Lührs, B.; Dahlmann, K.; Grewe, V.; Linke, F.; Yin, F.; Klingaman, E.; Shine, K.P. Climate-Optimized Trajectories and Robust Mitigation Potential: Flying ATM4E. Aerospace 2020, 7, 156. https://doi.org/10.3390/aerospace7110156
Lührs et al., Lührs, B.; Linke, F.; Matthes, S.; Grewe, V.; Yin, F. Climate Impact Mitigation Potential of European Air Traffic in a Weather Situation with Strong Contrail Formation. Aerospace 2021, 8, 50. https://doi.org/10.3390/aerospace8020050
Matthes, S.; Lim, L.; Burkhardt, U.; Dahlmann, K.; Dietmüller, S.; Grewe, V.; Haslerud, A.S.; Hendricks, J.; Owen, B.; Pitari, G.; Righi, M.; Skowron, A. Mitigation of Non-CO2 Aviation’s Climate Impact by Changing Cruise Altitudes. Aerospace 2021, 8, 36. https://doi.org/10.3390/aerospace8020036
ECATS Special Issues, „Making Aviation Sustainable”
DLR Magazin, No. 164, Following the Yellow Brick Road, Page 24, April 2020.