Review: The Effects of Supersonic Aviation on Ozone and Climate

When working towards regulation of supersonic aviation, a comprehensive understanding of the global climate effect of supersonic aviation is required in order to develop future regulatory issues. Such research requires a comprehensive overview of existing scientific literature having explored the climate effect of aviation. This review article provides an overview on earlier studies assessing the climate effects of supersonic aviation, comprising non-CO2 effects. An overview on the historical evaluation of research focussing on supersonic aviation and its environmental impacts is provided, followed by an overview on concepts explored and construction of emission inventories. Quantitative estimates provided for individual effects are presented and compared. Subsequently, regulatory issues related to supersonic transport are summarised. Finally, requirements for future studies, e.g., in emission scenario construction or numerical modelling of climate effects, are summarised and main conclusions discussed.

Eco-efficient flight trajectories – Using a Lagrangian approach in EMAC to investigate contrail formation in the mid latitudes

<p>Air transport has for a long time been linked to environmental issues like pollution, noise and climate change. While CO2 emissions are the main focus in public discussions, non-CO2 emissions of aviation may have a similar impact on the climate as aviation's carbon dioxide, e.g. contrail cirrus, nitrogen oxides or aviation induced cloudiness. While the effects of CO2 on climate are independent of location and situation during release, non-CO2 effects such as contrail formation vary depending on meteorological background. Previous studies investigated the influence of different weather situations on aviation’s climate change contribution, identifying climate sensitive regions and generating data products which enable air traffic management (ATM) to plan for climate optimized trajectories.</p> <p>The research presented here focuses on the further development of methods to determine the sensitivity of the atmosphere to aviation emissions with respect to climate effects in order to determine climate optimized aircraft trajectories. While previous studies focused on characterizing the North Atlantic Flight Corridor region, this study aims to extend the geographic scope by performing Lagrangian simulations in a global climate model EMAC for the northern hemispheric extratropical regions and tropical latitudes. This study addresses how realistically the physical conditions and processes for contrail formation and life cycle are represented in the upper troposphere and lower stratosphere by comparing them to airborne observations (HALO measurement campaign, CARIBIC/IAGOS scheduled flight measurements), examining key variables such as temperature or humidity. Direct comparison of model data with observations using clusters of data provides insight into the extent to which systematic biases exist that are relevant to the climate effects of contrails. We perform this comparison for different vertical resolutions to assess which vertical resolution in the EMAC model is well suited for studying contrail formation. Together with this model evaluation using aircraft measurements, the overall concept for studying the life cycle of contrails in the modular global climate model EMAC is introduced. Hereby, the concept for the development of a MET service that can be provided to ATM to evaluate contrail formation and its impact on the climate along planned aircraft trajectories is presented.</p> <p>Within the ClimOP collaborative project, we can investigate which physical processes determine the effects of contrails on climate and study their spatial and temporal variation. In addition, these climate change functions enable case studies that assess the impact of contrails on climate along trajectories and use alternative trajectories that avoid these regions of the atmosphere that have the potential to form contrails with a large radiative effect.</p> <p>This study is part of the ClimOP project and has received funding from European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement N° 875503 (ClimOP) and from the SESAR Joint Undertaking under grant agreements No 699395 (FlyATM4E). </p>

Future low-carbon electricity in Africa: how much material is needed?

African countries are expected to experience some of the worst climate effects, while trying to provide higher electricity access and increase wellbeing.Concrete, steel, and aluminium pre­sent the largest opportunities for action, given their high mass or embodied emissions projections.Embodied emissions related to material use for electricity plants are evaluated in three scenarios: a refer­ence scenario, and two scenarios related to the Paris Agreement (where renewable energy increases), resulting in higher embodied emissions as renewables are integrated.Pursuing strategies to increase the use of renewables should be done along material efficiency strategies to reach the total low-carbon potential.

Understanding the Climate Effects of Anthropogenic Aerosols

Anthropogenic aerosols alter the climate by scattering and absorbing the incoming solar radiation and by modifying clouds’ optical properties, causing a global cooling or warming effect. Anthropogenic aerosols are partly co-emitted with anthropogenic greenhouse gases, and future climate mitigation actions lead to the decline of anthropogenic aerosols’ cooling effect. However, the exact cooling effect is still uncertain. Part of this uncertainty is related to the structural differences of current climate models. This work evaluates the present-day anthropogenic aerosol temperature and precipitation effect and factors affecting the model difference. The key objectives of this thesis were: 1) What are the climate effects of present-day anthropogenic aerosols?, 2) What mechanisms drive the model-to-model differences?, and 3) How do future reductions affect local and global climates? The global models ECHAM6 and NorESM1 were used to evaluate the present-day climate effects with theidentical anthropogenic aerosol scheme MACv2-SP. Results reveal that an identical anthropogenic aerosol description does not reduce the uncertainty related to anthropogenic aerosol climate effects, and the difference in the estimated difference is due to model dynamics and oceans. The key mechanism driving the difference in the models was evaluated using data from the Precipitation Driven Model Intercomparison Project (PRMIP). Similar mechanisms drive the model-to-model difference for greenhouse gases and aerosols, where the key drivers are the differences in water vapor, the vertical temperature structure of the atmosphere, and sea ice and snow cover changes. However, on a regional scale, the key drivers differ. Future anthropogenic aerosol effects were evaluated using new CMIP6 data. This work shows the importance of anthropogenic aerosols for current and future climate change. For amore accurate assessment of climate impacts of anthropogenic aerosols, one needs to also consider remote effects of the local aerosols. The Arctic regions are particularly sensitive to midlatitude aerosols, such as Asian aerosols, which are expected to decline in the next decades. To gain a more accurate estimation of anthropogenic aerosols, it is not sufficient to only focus on composition and geographical distribution of aerosols, as the dynamic response of climate is also important. On global temperature results did not indicate clear aerosols signal, however future temperature development over the Asian regions is modulated by the future Asian aerosol emissions.

Assessing Pathways of Climate Change Effects in SpaDES: An Application to Boreal Landbirds of Northwest Territories Canada

Distributions of landbirds in Canadian northern forests are expected to be affected by climate change, but it remains unclear which pathways are responsible for projected climate effects. Determining whether climate change acts indirectly through changing fire regimes and/or vegetation dynamics, or directly through changes in climatic suitability may allow land managers to address negative trajectories via forest management. We used SpaDES, a novel toolkit built in R that facilitates the implementation of simulation models from different areas of knowledge to develop a simulation experiment for a study area comprising 50 million ha in the Northwest Territories, Canada. Our factorial experiment was designed to contrast climate effects pathways on 64 landbird species using climate-sensitive and non-climate sensitive models for tree growth and mortality, wildfire, and landbirds. Climate-change effects were predicted to increase suitable habitat for 73% of species, resulting in average net gain of 7.49 million ha across species. We observed higher species turnover in the northeastern, south-central (species loss), and western regions (species gain). Importantly, we found that most of the predicted differences in net area of occupancy across models were attributed to direct climate effects rather than simulated vegetation change, despite a similar relative importance of vegetation and climate variables in landbird models. Even with close to a doubling of annual area burned by 2100, and a 600 kg/ha increase in aboveground tree biomass predicted in this region, differences in landbird net occupancy across models attributed to climate-driven forest growth were very small, likely resulting from differences in the pace of vegetation and climate changes, or vegetation lags. The effect of vegetation lags (i.e., differences from climatic equilibrium) varied across species, resulting in a wide range of changes in landbird distribution, and consequently predicted occupancy, due to climate effects. These findings suggest that hybrid approaches using statistical models and landscape simulation tools could improve wildlife forecasts when future uncoupling of vegetation and climate is anticipated. This study lays some of the methodological groundwork for ecological adaptive management using the new platform SpaDES, which allows for iterative forecasting, mixing of modeling paradigms, and tightening connections between data, parameterization, and simulation.

Fuel-Operated Auxiliary Heaters Are a Major Additional Source of Vehicular Particulate Emissions in Cold Regions

Fuel-operated auxiliary heaters (AHs) can be notable sources of particle emissions from vehicles. The emissions of AHs are unregulated, and the number of devices is high; therefore, they make considerable contributions to local air quality, and even the global emissions budget. Experiments for studying the emissions were performed in Finland for a total of eight selected vehicles with Original Equipment Manufacturer (OEM) AHs installed, including both diesel- and gasoline-operated heaters. We present the numerical results of particle emissions and compare the particle concentrations in the AH exhaust to values found in the tailpipe exhaust of the same vehicle. Our results show that the emissions from auxiliary heaters are typically several orders of magnitude higher than of a car exhaust when idling. This raises the question of whether the use of heaters is justified based on the goal to reduce total emissions from vehicle use; furthermore, whether fuel-operated heaters should also be applied in electric vehicles for cabin heating. More research will be needed to characterize the emissions more thoroughly to understand the air quality and climate effects from AHs, and to provide further recommendations on the use of these heaters.