Estimates show that aviation is responsible for 13% of transportation-related fossil fuel consumption and 2% of all anthropogenic CO2 emissions [2]. Although emission contributions from aviation are small, a large portion of the emissions takes place at altitudes where the emissions remain longer in the atmosphere than if emitted at the surface. After a small decline over the last few years, air traffic has increased since 2011, and the Federal Aviation Administration (FAA) expects domestic air traffic to grow at an annual rate of 3.5% over the next 20 years [3]. Global air traffic is expected to grow more rapidly than domestic air traffic at an annual rate of 4.8% from 2011 to 2030 [4]. The desire to accommodate growing air traffic needs while limiting the impact of aviation on the environment has led to research in green aviation with the goals of better scientific understanding, utilization of alternative fuels, introduction of new aircraft technology, and rapid operational changes.
Aviation operations affect the climate in several ways.
The climate impact of aviation is expressed in terms of “radiative forcing” (RF). RF is a perturbation to the balance between incoming solar radiation and outgoing infrared radiation at the top of the troposphere. The amount of outgoing infrared radiation depends on the concentration of atmospheric greenhouse gases (GHG). RF associated with each type of emission has an approximately linear relationship with global mean surface temperature change. CO2, water vapor, and other gases are unavoidable by-products of the combustion of fossil fuel; of these CO2 and water vapor are GHG resulting in a positive RF. Because of its abundance and long lifetime, CO2 has a long-term effect on climate change; the non-CO2 emissions have a short-term effect on climate change. The important non-CO2 impacts associated with aviation are water vapor, oxides of nitrogen (NOX), condensation trails (contrails) and cirrus clouds due to air traffic. Contrails are clouds that are visible trails of water vapor made by the exhaust of aircraft engines [5]. The latest estimates indicate that contrails caused by aircraft may be causing more climate warming today than all the residual CO2 emitted by aircraft [6].
Concluding Remarks
Initial results demonstrate that a contrail reduction policy involving altitude changes to aircraft flying distances greater than 500 miles applied on days with high contrail activity is more energy efficient than applying altitude changes to avoid contrails to all aircraft on all days. These results need to be evaluated further with a range of values covering uncertainties in contrail formation and RF associated with contrails.
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Evaluating the Impacts of Aviation on Climate Change 2007. Future ATM Concepts Evaluation Tool. Future Aircraft Traffic Management Concepts Evaluation Tool (FACET) Related Airport Cooperative Research Program (ACRP) Projects. PARTNER: Partnership for Air Transportation Noise and Emissions Reduction. Continuous Lower Emissions, Energy, and Noise (CLEEN) Program. The Continuous Lower Energy, Emissions and Noise (CLEEN) program is a NextGen effort to accelerate development and commercial deployment of environmentally promising aircraft technologies and sustainable alternative fuels.
The aircraft technologies focus on reduction in aircraft noise, emissions, and fuel burn. Under this program, FAA has awarded five-year agreements to Boeing, General Electric, Honeywell, Pratt & Whitney, and Rolls-Royce. These companies will match or exceed the awards in this cost-sharing program. The total federal investment is expected to be $125 million over five years. Specifically, CLEEN goals include developing and demonstrating: A complementary piece of the CLEEN Program to the technology and fuel development activities is an independent technology assessment.
This effort will: To learn more about the CLEEN program, please visit the links below: For information and materials on CLEEN II Industry Day: CLEEN II Industry Day – December 3, 2013. CAAFI - Home. Calendar | ATTREX. INCITE Researchers Explore How Aircraft Contrails Can Impact Climate | Argonne Leadership Computing Facility. When aircraft in the United States were grounded for three days after the Sept. 11, 2001 terrorist attacks, scientists had a singular opportunity to study the effects of contrails—ice clouds generated by water exhaust gases from aircraft engines—on climate.
The scientists measured day and night temperatures to find out if contrails contributed to regional warming and/or global climate change. Some studies indicated that the absence of contrails during this grounding period increased the daily temperature range at the Earth’s surface, but this result is still a subject of scientific debate.
Nonetheless, there’s no question that the environmental impact of aviation represents a source of increasing concern among scientists and policymakers as the demand for air travel continues to grow. Aviation is one of the fastest growing sectors, with a projected twofold increase by 2020. Jet Biofuel Enlisted For Contrail Control. Contrails might be a punch line in the culture these days, thanks to the imaginative folks who have rechristened them “chemtrails” and embroidered them with elaborate theories involving government and corporate misdeed. But contrails are pretty serious business for a less conspiratorial reason: scientists believe these ice clouds generated by water exhaust gases from aircraft engines could have a real impact on the climate, perhaps by cooling temperatures during the day and warming them at night.
That’s where a new phase in an ongoing NASA study comes into play: The space agency recently began doing flights over the Southern California desert in which a DC-8 “flying laboratory” is testing the contrail consequences of using standard JP-8 jet fuel versus a 50-50 blend of JP-8 and a biofuel made from camelina plants. So what’s the problem with that? As CERFACS explains: When contrails spread to form cirrus clouds, they can persist for hours and extend over areas of several square kilometers. Sustainable Alternative Jet Fuels. Commercial aviation faces fuel cost, environmental, and energy security challenges that arise from petroleum based jet fuel use. Sustainable alternative jet fuels can help to address these challenges. Their use could reduce emissions that impact surface air quality and global climate while expanding domestic energy sources that diversify fuel supplies, contribute to price and supply stability, and generate economic development in rural communities.
The FAA is working to enable the U.S. use of one billion gallons per year of "drop-in" sustainable alternative jet fuels by 2018. Though they are created from renewable sources, drop-in fuels mimic the chemistry of petroleum jet fuel and can be used in today's aircraft and engines without modification and provide the same level of performance and safety as today's petroleum-derived jet fuel. Sustainable alternative jet fuel development and deployment is also a key element of the U.S. Information Exchange and Coordination. Environmentally Responsible Aviation (ERA) Project. Created in 2009 as part of NASA's Aeronautics Research Mission Directorate's Integrated Systems Research Program, the Environmentally Responsible Aviation (ERA) Project explores and documents the feasibility, benefits and technical risk of vehicle concepts and enabling technologies to reduce aviation’s impact on the environment.
Current-generation aircraft already benefit from the NASA investments in aeronautical research that have improved fuel efficiencies, lowered noise levels and reduced harmful emissions. Although substantial progress has been made, much more needs to be done. Forecasts call for the nation's air transportation system to expand significantly within the next two decades. Such an expansion could bring adverse environmental impacts. To neutralize or reduce these impacts is the goal of the ERA Project and its focused research. The project is organized to:
Climate optimized routing of flights - Colloquium on Aviation and Climate Chante - 6_Schumann_Wmo.pdf. Air Tansportation Systems - CATS – Climate Compatible Air Transport System. Model for Assessing Global Exposure to the Noise of Transport Aircraft (MAGENTA) MAGENTA is a computer model used to estimate the number of people exposed to significant aircraft noise worldwide.
The original MAGENTA model development was done with the Committee on Aviation Environmental Protection (CAEP) under the International Civil Aviation Organization (ICAO) to assess the worldwide aviation noise climate. The computational core of MAGENTA is FAA’s Integrated Noise Model (INM), the most widely used computer program to calculate aircraft noise around airports. Major assumptions on local traffic use come from getting INM datasets developed for an airport. The noise studies obtained from U.S. airports have gone through thorough public review; either under the National Environmental Policy Act (NEPA) requirements or as part of a land use compatibility program. A U.S. version of the global MAGENTA model was developed to determine the noise exposure in the U.S. using data on aircraft and operations specific to U.S. airports. System for Assessing Aviation's Global Emissions (SAGE) incorporated into the Aviation Environmental Design Tool (AEDT)
SAGE was a high fidelity computer model used to predict aircraft fuel burn and emissions for all commercial (civil) flights globally. The model was used to analyze scenarios from a single flight to airport, country, regional, and global levels. In addition, SAGE dynamically modeled aircraft performance, fuel burn and emissions. The United States Federal Aviation Administration (FAA) Office of Environment and Energy (AEE) developed SAGE with support from the Volpe National Transportation Systems Center (Volpe), the Massachusetts Institute of Technology (MIT) and the Logistics Management Institute (LMI). Its purpose was to provide FAA, and indirectly the international aviation community, with a tool to evaluate the effects of various policy, technology, and operational scenarios on aircraft fuel use and emissions.
Concluded at Version 1.5, SAGE was not developed for use on a stand alone personal computer; it was an FAA government research tool. Aircraft Fuel Burn and Emissions Analysis. Emissions and Dispersion Modeling System (EDMS) The Emissions and Dispersion Modeling System (EDMS) was developed in the mid-1980s as a complex source microcomputer model designed to assess the air quality impacts of proposed airport development projects. What is EDMS Designed to Do? The Emissions and Dispersion Modeling System (EDMS) is designed to assess the air quality impacts of airport emission sources, particularly aviation sources, which consist of: Aircraft Auxiliary power units Ground support equipment Ground access vehicles Stationary sources EDMS is one of the few air quality assessment tools specifically engineered for the aviation community. It includes: FAA Required Model In 1998, FAA revised its policy on air quality modeling procedures to identify EDMS as the Required Model (PDF) to perform air quality analyses for aviation sources instead of the preferred model.
EDMS 5.1.4.1 (August 2013) Best Practice Document for Using EDMS with USEPA MOVES The FAA has produced a best practice document for using EDMS with the U.S. Aviation environmental Portfolio Management Tool (APMT) The Aviation Environmental Portfolio Management Tool (APMT) computes the environmental impacts of aircraft operations, their interrelationships and economic consequences using the following elements: APMT-Impacts, APMT-Cost Benefit, and APMT-Economics. The APMT-Impacts estimates the environmental impacts of aircraft operations through changes in health and welfare endpoints for climate, air quality, and noise. It is part of a series of tools based on the latest research understanding to provide a thorough assessment of how changes to one or more aviation technologies or operations will affect many other aspects of aviation and society.
Cost benefit analyses with the APMT-Cost Benefit combines output from multiple Tools Suite elements to facilitate weighing total expected costs against total expected benefits for aviation's environmental effects under different policy, technology, operational and market scenarios. For more information, visit the MIT website. Users Developers Availability. Environmental Design Space (EDS) EDS is a numerical simulation based on physics that is capable of estimating source noise, exhaust emissions, and performance for potential future aircraft designs under different technological, operational, policy, and market scenarios.
While the primary focus of EDS is future aircraft designs (which includes technology modifications to existing aircraft), EDS is capable of analyzing existing aircraft designs (current technology levels), including the simulation of existing aircraft with higher fidelity than is possible using existing noise and emissions tools and inventories. EDS is linked to the Aviation Environmental Tools Suite by providing future aircraft design characteristics to AEDT and AMPT. Users EDS is currently being developed for use with US Next Generation Air Transportation System (NextGen) advanced technology goals analyses and to support the future International Civil Aviation Organization (ICAO) Committee on Aviation Environmental Protection (CAEP) analyses. Developers. Aviation Environmental Design Tool (AEDT) Performance Based Navigation (PBN) Implementation And Usage.
Next Generation Air Transportation System (NextGen) CALIPSO - Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. NASA LaRC Satellite Imagery and Cloud Products. Formation flying civilian airliners? Air Tansportation Systems - Formationsflug ziviler Verkehrsflugzeuge. Der Formationsflug von zivilen Verkehrsflugzeugen verspricht analog zum natürlichen Vorbild der Zugvögel signifikante Treibstoffeinsparungen und dadurch eine Reduktion der Betriebskosten und des CO2-Ausstoßes. Die Integration dieses Verfahrens in das Lufttransportsystem stellt jedoch sowohl technisch als auch operationell eine große Herausforderung dar. Das Institut für Lufttransportsysteme untersucht die verschiedenen Einflüsse und Abhängigkeiten des Formationsfluges im Lufttransportsystem mit dem Ziel, eine Bewertung des systemweit operationell erreichbaren Potenzials zu ermöglichen.
Dabei werden nicht nur die Trajektorien der einzelnen an der Formation teilnehmenden Flugzeuge betrachtet, sondern beispielsweise auch die Routenführung der Gesamtformationen. Durch das Fliegen in Formation ergeben sich zudem Effekte, die die durch die Formation erreichte Treibstoffeinsparung wieder reduzieren. Partner:Laufzeit: 2015+Projektträger: DLR. Centre for Air Transport and the Environment - Climate Change. Omega addressed main question relating to climate and aviation. Non-CO2 impacts were the main focus with studies looking at contrail formation and modelling the resultant impacts.
Omega linked aero-technology modelling and climate effects modelling to understand the relationship of emissions and feeding knowledge into work for operational and market solutions. Global temperature change implications of aviation growth (link to the project) This study generated information on global temperature implications of the range of aviation scenarios in terms of projected surface temperature change and on the contribution of aviation to such change drawing upon broader Inter-Governmental Panel on Climate Change data. Click here for the Project Summary and the Final Report Jet engine exhaust and climate change influencing engine design and operations The project aimed to understand how to balance the effects of CO2, NOx and contrails with the aim of improving aircraft and engine design and operation.
Aviation Climate Change Research Initiative (ACCRI) Workshop on the Impacts of Aviation on Climate Change: A Report of Findings and Recommendations June 7-9, 2006, Cambridge, MA. Ice-Supersaturated Regions. Atmospheric science: Seeing through contrails : Nature Climate Change. Aviation is at present responsible for about 3% of all fossil fuel carbon dioxide emissions, but an estimated 2–14% of anthropogenic climate forcing1. Furthermore, its contribution to climate forcing could triple by 2050, according to some scenarios1. As such, mitigating the impact of aviation on climate has become a subject of considerable public and political interest. The debate is complicated, however, by the fact that aviation's climate impact results from a number of different factors, as well as by the large uncertainty in the effect that some of these factors have on climate.
Writing in Nature Climate Change, Burkhardt and Kärcher3 present a global modelling study that quantifies the climate effect of 'spreading contrails' — the least well quantified of all the aviation-related climate-forcing agents. Aircraft-engine emissions are mostly composed of carbon dioxide, water vapour, nitrogen oxides, sulphur oxides and aerosol particles. Full size image (148 KB) Black Carbon and Warming: It’s Worse than We Thought by Carl Zimmer: Yale Environment 360. 17 Jan 2013: Analysis by carl zimmer It rises from the chimneys of mansions and from simple hut stoves. It rises from forest fires and the tail pipes of diesel-fueled trucks rolling down the highway, and from brick kilns and ocean liners and gas flares.
Every day, from every occupied continent, a curtain of soot rises into the sky. What soot does once it reaches the atmosphere has long been a hard question to answer. To get a clear sense of soot — which is known to scientists as black carbon — an international team of 31 atmospheric scientists has worked for the past four years to analyze all the data they could. The new estimate of black carbon’s heat-trapping power is twice that made by the IPCC.
Ramanathan of the Scripps Institution for Oceanography, an expert on atmospheric chemistry who was not involved in the study. The big result that jumps off the page is that black carbon plays a much bigger role in global warming than many scientists previously thought. How can this be? Black carbon is a larger cause of climate change than previously assessed. From the International Geosphere-Biosphere Programme via Eurekalert, some of the heat gets taken off CO2 as the ‘big kahuna’ of forcings, now there is another major player, one that we can easily do something about. I’ve often speculated that black carbon is a major forcing for Arctic sea ice, due to examples like this one. – Anthony Reducing diesel engine emissions would reduce warming This shows black carbon processes in the climate system. Credit: American Geophysical Union 2013.
Credit D. W. Black carbon is the second largest man-made contributor to global warming and its influence on climate has been greatly underestimated, according to the first quantitative and comprehensive analysis of this issue. The landmark study published in the Journal of Geophysical Research-Atmospheres today says the direct influence of black carbon, or soot, on warming the climate could be about twice previous estimates. Co-lead author David Fahey from the U.S. Other co-authors are: T. Like this: The Double-Sided Sensitivity of Clouds to Air Pollution & Intentional Seeding.
Energy Efficient Contrail Mitigation Strategies for Reducing the Environmental Impact of Aviation 2013. Evaluating the Importance of Aviation on Climate Change 2008.