Mitigating the Climate Impact from Aviation: Achievements and Results of the DLR WeCare Project
29 Jun 2017-Aerospace Science and Technology (Multidisciplinary Digital Publishing Institute)-Vol. 4, Iss: 3, pp 34
TL;DR: The WeCare project (Utilizing Weather information for Climate efficient and eco-efficient future aviation) as mentioned in this paper 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.
About: This article is published in Aerospace Science and Technology.The article was published on 2017-06-29 and is currently open access. It has received 73 citations till now. The article focuses on the topics: Aviation & Climate change.
Citations
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01 Jan 2000
TL;DR: In this paper, a parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters, including tropical, mid-latitude, and subarctic summer and winter atmospheres.
Abstract: A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm−2 daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.
163 citations
TL;DR: In this paper, the authors analyze and compare two CO 2 trading schemes for aviation from an environmental and competition perspective: the EU Emissions Trading Scheme (EU ETS) and the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).
87 citations
TL;DR: In this article, the authors show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals.
Abstract: Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO2 and non-CO2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.
74 citations
TL;DR: In this article, the authors used the compact Earth system model OSCARv2.2 to assess the climate impact of present and future civil aviation carbon dioxide (CO2) emissions.
Abstract: The compact Earth system model OSCARv2.2 is used to assess the climate impact of present and future civil aviation carbon dioxide (CO2) emissions. The impact of aviation CO2 on future climate is quantified over the 1940–2050 period, extending some simulations to 2100 and using different aviation CO2 emission scenarios and two background Representative Concentrations Pathways (RCP2.6 and RCP6.0) for other emission sectors. Several aviation scenarios including weak to strong mitigation options are considered with emissions ranging from 386 MtCO2/year (Factor 2 scenario) to 2338 MtCO2/year (ICAO based scenario) in 2050. As a reference, in 2000, the calculated impact of aviation CO2 emissions is 9.1 ± 2 mK (0.8% of the total anthropogenic warming associated to fossil fuel emissions). In 2050, on a climate trajectory in line with the Paris Agreement limiting the global warming below 2 °C (RCP2.6), the impact of the aviation CO2 emissions ranges from 26 ± 2 mK (1.4% of the total anthropogenic warming associated to fossil fuel emissions) for an ambitious mitigation strategy scenario (Factor 2) to 39 ± 4 mK (2.0% of the total anthropogenic warming associated to fossil fuel emissions) for the least ambitious mitigation scenario of the study (ICAO based). On the longer term, if no significant emission mitigation is implemented for the aviation sector, the associated warming could further increase and reach a value of 99.5 mK ± 20 mK in 2100 (ICAO based), which corresponds to 5.2% of the total anthropogenic warming under RCP2.6. The contribution of CO2 is estimated to represent 36%–51% of the total aviation radiative forcing of climate including short-term climate forcers. However, due to its long residence time in the atmosphere, aviation CO2 will have a major contribution on decadal time scales. These additional short-terms forcers are subject to large uncertainties and will be analysed in forthcoming studies.
62 citations
17 Jun 2021
TL;DR: In this article, the authors provided experimental evidence that burning low aromatic sustainable aviation fuel can result in a 50 to 70% reduction in soot and ice number concentrations and an increase in ice crystal size.
Abstract: Contrail cirrus account for the major share of aviation’s climate impact. Yet, the links between jet fuel composition, contrail microphysics and climate impact remain unresolved. Here we present unique observations from two DLR-NASA aircraft campaigns that measured exhaust and contrail characteristics of an Airbus A320 burning either standard jet fuels or low aromatic sustainable aviation fuel blends. Our results show that soot particles can regulate the number of contrail cirrus ice crystals for current emission levels. We provide experimental evidence that burning low aromatic sustainable aviation fuel can result in a 50 to 70% reduction in soot and ice number concentrations and an increase in ice crystal size. Reduced contrail ice numbers cause less energy deposition in the atmosphere and less warming. Meaningful reductions in aviation’s climate impact could therefore be obtained from the widespread adoptation of low aromatic fuels, and from regulations to lower the maximum aromatic fuel content. Burning sustainable aviation fuel blends with low levels of soot-producing aromatic components can result in a 50 to 70% reduction in soot and ice number concentrations and an increase in ice crystal size, suggest measurements of exhaust and contrail characteristics in two aircraft campaigns.
61 citations
References
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Joint Global Change Research Institute1, National Center for Atmospheric Research2, Victoria University of Wellington3, Electric Power Research Institute4, Netherlands Environmental Assessment Agency5, Finnish Environment Institute6, National Institute for Environmental Studies7, Met Office8, International Institute for Applied Systems Analysis9, Vienna University of Technology10, National Oceanic and Atmospheric Administration11, Stanford University12, Oak Ridge National Laboratory13
TL;DR: A new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community is described.
Abstract: Advances in the science and observation of climate change are providing a clearer understanding of the inherent variability of Earth's climate system and its likely response to human and natural influences. The implications of climate change for the environment and society will depend not only on the response of the Earth system to changes in radiative forcings, but also on how humankind responds through changes in technology, economies, lifestyle and policy. Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists. Here we describe a new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community.
5,670 citations
"Mitigating the Climate Impact from ..." refers methods in this paper
...It provides historical emissions up to the year 2000 and future projections based on Representative Concentration Pathways (RCPs [124]) up to the year 2100....
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TL;DR: In this article, the effects of aerosols on the climate system are discussed and different approaches how the climatic implications of these effects can be estimated globally as well as improvements that are needed in global climate models in order to better represent indirect aerosol effects are discussed.
Abstract: . Aerosols affect the climate system by changing cloud characteristics in many ways. They act as cloud condensation and ice nuclei, they may inhibit freezing and they could have an influence on the hydrological cycle. While the cloud albedo enhancement (Twomey effect) of warm clouds received most attention so far and traditionally is the only indirect aerosol forcing considered in transient climate simulations, here we discuss the multitude of effects. Different approaches how the climatic implications of these aerosol effects can be estimated globally as well as improvements that are needed in global climate models in order to better represent indirect aerosol effects are discussed in this paper.
2,327 citations
"Mitigating the Climate Impact from ..." refers background in this paper
...Aerosol particles can affect the planetary radiation budget both directly, by scattering and absorbing radiation, and indirectly, by perturbing the microphysical structure of clouds, thereby changing their albedo and lifetime [126]....
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National Center for Atmospheric Research1, University of Illinois at Urbana–Champaign2, German Aerospace Center3, Earth System Research Laboratory4, Cooperative Institute for Research in Environmental Sciences5, Centre national de la recherche scientifique6, Forschungszentrum Jülich7, International Institute for Applied Systems Analysis8, Manchester Metropolitan University9, Goddard Institute for Space Studies10, Joint Global Change Research Institute11, Netherlands Environmental Assessment Agency12, Cornell University13, Desert Research Institute14, Geophysical Fluid Dynamics Laboratory15
TL;DR: In this paper, the authors present a new dataset of gridded emissions covering the historical period (1850-2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude.
Abstract: We present and discuss a new dataset of gridded emissions covering the historical period (1850–2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude. The primary purpose of this inventory is to provide consistent gridded emissions of reactive gases and aerosols for use in chemistry model simulations needed by climate models for the Climate Model Intercomparison Program #5 (CMIP5) in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). Our best estimate for the year 2000 inventory represents a combination of existing regional and global inventories to capture the best information available at this point; 40 regions and 12 sectors are used to combine the various sources. The historical reconstruction of each emitted compound, for each region and sector, is then forced to agree with our 2000 estimate, ensuring continuity between past and 2000 emissions. Simulations from two chemistry-climate models is used to test the ability of the emission dataset described here to capture long-term changes in atmospheric ozone, carbon monoxide and aerosol distributions. The simulated long-term change in the Northern mid-latitudes surface and mid-troposphere ozone is not quite as rapid as observed. However, stations outside this latitude band show much better agreement in both present-day and long-term trend. The model simulations indicate that the concentration of carbon monoxide is underestimated at the Mace Head station; however, the long-term trend over the limited observational period seems to be reasonably well captured. The simulated sulfate and black carbon deposition over Greenland is in very good agreement with the ice-core observations spanning the simulation period. Finally, aerosol optical depth and additional aerosol diagnostics are shown to be in good agreement with previously published estimates and observations.
1,953 citations
"Mitigating the Climate Impact from ..." refers methods in this paper
...Emissions of short-lived gases (NOx, CO, SO2, Non-Methane Volatile Organic Carbons (NMVOC), and NH3) and aerosol species (black (BC) and organic carbon (OC)) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) inventory [123] were used as input to the model....
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TL;DR: In this paper, the ice nucleation active surface site (INAS) density is discussed as a simple and empirical normalized measure for ice nucleization activity, and the authors compare the results obtained with different methodologies.
Abstract: . A small subset of the atmospheric aerosol population has the ability to induce ice formation at conditions under which ice would not form without them (heterogeneous ice nucleation). While no closed theoretical description of this process and the requirements for good ice nuclei is available, numerous studies have attempted to quantify the ice nucleation ability of different particles empirically in laboratory experiments. In this article, an overview of these results is provided. Ice nucleation "onset" conditions for various mineral dust, soot, biological, organic and ammonium sulfate particles are summarized. Typical temperature-supersaturation regions can be identified for the "onset" of ice nucleation of these different particle types, but the various particle sizes and activated fractions reported in different studies have to be taken into account when comparing results obtained with different methodologies. When intercomparing only data obtained under the same conditions, it is found that dust mineralogy is not a consistent predictor of higher or lower ice nucleation ability. However, the broad majority of studies agrees on a reduction of deposition nucleation by various coatings on mineral dust. The ice nucleation active surface site (INAS) density is discussed as a simple and empirical normalized measure for ice nucleation activity. For most immersion and condensation freezing measurements on mineral dust, estimates of the temperature-dependent INAS density agree within about two orders of magnitude. For deposition nucleation on dust, the spread is significantly larger, but a general trend of increasing INAS densities with increasing supersaturation is found. For soot, the presently available results are divergent. Estimated average INAS densities are high for ice-nucleation active bacteria at high subzero temperatures. At the same time, it is shown that INAS densities of some other biological aerosols, like certain pollen grains, fungal spores and diatoms, tend to be similar to those of dust. These particles may owe their high ice nucleation onsets to their large sizes. Surface-area-dependent parameterizations of heterogeneous ice nucleation are discussed. For immersion freezing on mineral dust, fitted INAS densities are available, but should not be used outside the temperature interval of the data they were based on. Classical nucleation theory, if employed with only one fitted contact angle, does not reproduce the observed temperature dependence for immersion nucleation, the temperature and supersaturation dependence for deposition nucleation, and the time dependence of ice nucleation. Formulations of classical nucleation theory with distributions of contact angles offer possibilities to overcome these weaknesses.
946 citations
"Mitigating the Climate Impact from ..." refers background in this paper
...They are known to act as ice nuclei for heterogeneous ice formation processes in mixed-phase and cirrus clouds [44]....
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TL;DR: In this article, the authors presented updated values of aviation radiative forcing (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% over the period 2000-2005.
910 citations