Mitigating the Climate Impact from Aviation: Achievements and Results of the DLR WeCare Project

Abstract

Abstract:The WeCare project (Utilizing Weather information for Climate efficient and eco efficient future aviation), an internal project of the German Aerospace Center (Deutsches Zentrum für Luft-und Raumfahrt, DLR), aimed at finding solutions for reducing the climate impact of aviation based on an improved understanding of the atmospheric impact from aviation by making use of measurements and modeling approaches. WeCare made some important contributions to advance the scientific understanding in the area of atmospheric and air transportation research. We characterize contrail properties, show that the aircraft type significantly influences these properties, and how contrail-cirrus interacts with natural cirrus. Aviation NO x emissions lead to ozone formation and we show that the strength of the ozone enhancement varies, depending on where within a weather pattern NO x is emitted. These results, in combination with results on the effects of aerosol emissions on low cloud properties, give a revised view on the total radiative forcing of aviation. The assessment of a fleet of strut-braced wing aircraft with an open rotor is investigated and reveals the potential to significantly reduce the climate impact. Intermediate stop operations have the potential to significantly reduce fuel consumption. However, we find that, if only optimized for fuel use, they will have an increased climate impact, since non-CO 2 effects compensate the reduced warming from CO 2 savings. Avoiding climate sensitive regions has a large potential in reducing climate impact at relatively low costs. Taking advantage of a full 3D optimization has a much better eco-efficiency than lateral re-routings, only. The implementation of such operational measures requires many more considerations. Non-CO 2 aviation effects are not considered in international agreements. We showed that climate-optimal routing could be achieved, if market-based measures were in place, which include these non-CO 2 effects. An alternative measure to foster climate-optimal routing is the closing of air spaces, which are very climate-sensitive. Although less effective than an unconstrained optimization with respect to climate, it still has a significant potential to reduce the climate impact of aviation. By combining atmospheric and air transportation research, we assess climate mitigation measures, aiming at providing information to aviation stakeholders and policy-makers to make aviation more climate compatible.

The contribution of aviation NOx emissions to climate change: are we ignoring methodological flaws?

“…It is important to stress that this correction of flaws has two major implications: first on the weighting of individual aviation non-CO 2 effects with respect to their impact on climate and second how to assess mitigation options. Concerning the first implication, the aviation CO 2 and NO x emissions lead to a RF in the year 2005 in the range of 25 to 30 mW m −2 ([4] and this work) and contrails to around 50 mW m −2 [5,38].…”

The contribution of carbon dioxide emissions from the aviation sector to future climate change

“…This is in particular the case for aircraft NO x emissions affecting tropospheric ozone and the methane lifetime, emissions or formation of particles (black carbon, sulphates, nitrates) and, more importantly, formation of linear contrails and induced cloudiness (Karcher 2018). The aviation CO 2 RF of climate is estimated to represent 36%-51% of this total forcing including short-term climate forcers (Lee et al 2009, Grewe et al 2017, Karcher 2018. These additional terms are subject to large uncertainties and will be analysed in forthcoming studies with the OSCAR compact carbon cycle-climate change model in order to account for the different lifetimes of the various climate agents involved or with the more complex LMDz-INCA chemistry-climate model.…”

“…The aviation climate impact is quantified over the 1940-2050 period with an extension to 2100, according to updated aviation emission scenarios and for the two aforementioned RCP (RCP2.6 and RCP6.0) storylines for background of CO 2 concentration and climate future evolution. The contribution of CO 2 is estimated to represent 36%-51% of the total aviation RF of climate including short-term climate forcers (Lee et al 2009, Grewe et al 2017, Karcher 2018. However, due to its long residence time in the atmosphere, aviation CO 2 will have a major contribution on decadal time scales.…”

Future Fuels—Analyses of the Future Prospects of Renewable Synthetic Fuels

“…Among others, these projections will contain a global air traffic forecast that allows for the quantification of future alternative kerosene demand in Germany until 2050. Applying a comprehensive passenger air travel demand prediction and modelling system described in [20], all commercial flights departing from Germany are modelled. For this purpose, the system first determines passenger origin-destination demand based on assumptions regarding the development of certain socio-economic factors.…”