Aviation and the environment
Encyclopedia
The environmental impact of aviation occurs because aircraft engine
s emit noise
, particulates, and gases which contribute to climate change
and global dimming
. Despite emission reductions from automobiles and more fuel-efficient and less polluting turbofan
and turboprop
engines, the rapid growth of air travel
in recent years contributes to an increase in total pollution attributable to aviation
. In the European Union
, greenhouse gas
emissions from aviation increased by 87% between 1990 and 2006.
There is an ongoing debate about possible taxation of air travel and the inclusion of aviation in an emissions trading
scheme, with a view to ensuring that the total external costs of aviation are taken into account.
, most forms of aviation
release carbon dioxide
(CO2) and other greenhouse gases into the Earth's atmosphere
, contributing to the acceleration of global warming
and (in the case of CO2) ocean acidification
.
In addition to the CO2 released by most aircraft in flight through the burning of fuels such as Jet-A
(turbine aircraft) or Avgas
(piston aircraft), the aviation industry also contributes greenhouse gas
emissions from ground airport
vehicles and those used by passengers and staff to access airports, as well as through emissions generated by the production of energy used in airport buildings, the manufacture of aircraft
and the construction of airport infrastructure.
While the principal greenhouse gas
emission from powered aircraft in flight is CO2, other emissions may include nitric oxide
and nitrogen dioxide
, (together termed oxides of nitrogen or NOx), water vapour and particulates
(soot and sulfate particles), sulfur oxides, carbon monoxide
(which bonds with oxygen
to become CO2 immediately upon release), incompletely burned hydrocarbons, tetra-ethyl lead
(piston aircraft only), and radicals such as hydroxyl
, depending on the type of aircraft in use.
The contribution of civil aircraft-in-flight to global CO2 emissions has been estimated at around 2%. However, in the case of high-altitude airliners which frequently fly near or in the stratosphere
, non-CO2 altitude-sensitive effects may increase the total impact on anthropogenic (man-made) climate change
significantly.
Carbon dioxide (CO2)
Oxides of nitrogen (NOx)
Water vapor (H2O)
Particulates
For perspecitve, per passenger a typical economy-class New York to Los Angeles round trip produces about 715 kg (1574 lb) of CO2, but is equivalent to 1,917 kg (4,230 lb) of CO2 when the high altitude “climatic forcing” effect is taken into account. Within the categories of flights above, emissions from scheduled jet flights are substantially higher than turboprop or chartered jet flights. The emissions above are similar to a four-seat car with one person on board; however, flying trips often cover longer distances than would be undertaken by car, so the total emissions are much higher. About 60% of aviation emissions arise from international flights, and these flights are not covered by the Kyoto Protocol and its emissions reduction targets.
Per passenger kilometre, figures from British Airways suggest carbon dioxide emissions of 0.1 kg for large jet airliners (a figure which does not account for the production of other pollutants or condensation trails).
(IPCC) has estimated that aviation’s total climate impact is some 2-4 times that of its direct CO2 emissions alone (excluding the potential impact of cirrus cloud enhancement). This is measured as radiative forcing
. While there is uncertainty about the exact level of impact of NOx and water vapour, governments have accepted the broad scientific view that they do have an effect. Globally in 2005, aviation contributed "possibly as much as 4.9% of radiative forcing." UK government policy statements have stressed the need for aviation to address its total climate change impacts and not simply the impact of CO2.
The IPCC has estimated that aviation is responsible for around 3.5% of anthropogenic climate change, a figure which includes both CO2 and non-CO2 induced effects. The IPCC has produced scenarios estimating what this figure could be in 2050. The central case estimate is that aviation’s contribution could grow to 5% of the total contribution by 2050 if action is not taken to tackle these emissions, though the highest scenario is 15%. Moreover, if other industries achieve significant cuts in their own greenhouse gas emissions, aviation’s share as a proportion of the remaining emissions could also rise.
Continual Increases in Travel & Freight
From 1992 to 2005, passenger kilometers increased 5.2% per year, even with the disruptions of 9/11 and two significant wars. Since the onset of the current recession:
In a 2008 presentation and paper Professor Kevin Anderson
of the Tyndall Centre for Climate Change Research
showed how continued aviation growth in the UK threatens the ability of that nation to meet CO2 emission reduction goals necessary to contain the century-end temperature increase to even 4 or 6C°. (See also: the 4 Degrees and Beyond International Climate Conference (2009)
and its proceedings.) His charts show the projected domestic aviation carbon emission increase for the UK as growing from 11 MT in 2006 to 17 MT in 2012, at the UK's historic annual emission growth rate of 7%. Beyond 2012 if the growth rate were reduced to 3% yearly, carbon emissions in 2030 would be 28 MT, which is 70% of the UK's entire carbon emissions budget that year for all sectors of society. This work also suggests the foreseeable future which confronts many other nations that have high dependency on aviation. "Hypermobile Travelers," an academic study by Stefan Gössling
et al. (2009) in the book "Climate Change and Aviation," also points to the dilemma caused by the increasing hypermobility of air travelers
both in particular nations and globally.
Increasing efficiencies of aircraft and their operation
Modern jet aircraft are significantly more fuel efficient (and thus emit less CO2 in particular) than 30 years ago. Moreover, manufacturers have forecast and are committed to achieving reductions in both CO2 and NOx emissions with each new generation of design of aircraft and engine. Thus, the accelerated introduction of more modern aircraft represents an opportunity to reduce emissions per passenger kilometre flown. However, aircraft are major investments that endure for many decades, and replacement of the international fleet is therefore a long-term proposition which will greatly delay realizing the climate benefits of many kinds of improvements. Engines can be changed at some point, but nevertheless airframe
s have a long life.
Other opportunities arise from the optimisation of airline timetables, route networks and flight frequencies to increase load factors (minimise the number of empty seats flown), together with the optimisation of airspace. However, these are each one-time gains, and as these opportunities are successively fulfilled, diminishing returns can be expected from the remaining opportunities.
Another possible reduction of the climate-change impact is the limitation of cruise altitude of aircraft. This would lead to a significant reduction in high-altitude contrails for a marginal trade-off of increased flight time and an estimated 4% increase in CO2 emissions. Drawbacks of this solution include very limited airspace capacity to do this, especially in Europe and North America and increased fuel burn because jet aircraft are less efficient at lower cruise altitudes.
While they are not suitable for long-haul or transoceanic flights, turboprop aircraft used for commuter flights bring two significant benefits: they often burn considerably less fuel per passenger mile, and they typically fly at lower altitudes, well inside the tropopause, where there are no concerns about ozone or contrail production.
technology for use in jet aircraft. As part of this test Virgin Atlantic Airways
flew a Boeing 747
from London Heathrow Airport to Amsterdam Schiphol Airport on 24 February 2008, with one engine burning a combination of coconut oil
and babassu oil
. Greenpeace
's chief scientist Doug Parr said that the flight was "high-altitude greenwash
" and that producing organic oils to make biofuel
could lead to deforestation and a large increase in greenhouse gas emissions. Also,
the majority of the world's aircraft are not large jetliners but smaller piston aircraft, and with major modifications many are capable of using ethanol
as a fuel. Another consideration is the vast amount of land that would be necessary to provide the biomass feedstock needed to support the needs of aviation, both civil and military.
In December 2008 an Air New Zealand
jet completed the world's first commercial aviation test flight partially using jatropha
-based fuel. Jatropha, used for biodiesel, can thrive on marginal agricultural land where many trees and crops won't grow, or would produce only slow growth yields. Air New Zealand set several general sustainability criteria for its Jatropha, saying that such biofuels must not compete with food resources, that they must be as good as traditional jet fuels, and that they should be cost competitive with existing fuels.
In January 2009, Continental Airlines
used a sustainable biofuel to power a commercial aircraft for the first time in North America. This demonstration flight marks the first sustainable biofuel demonstration flight by a commercial carrier using a twin-engined aircraft, a Boeing 737-800
, powered by CFM International CFM56-7B engines. The biofuel blend included components derived from algae and jatropha plants.
One fuel biofuel alternative to avgas
that is under development is Swift Fuel. Swift fuel was approved as a test fuel by ASTM International
in December 2009, allowing the company to continue their research and to pursue certification testing. Mary Rusek, president and co-owner of Swift Enterprises predicted at that time that "100SF will be comparably priced, environmentally friendlier and more fuel-efficient than other general aviation fuels on the market".
As of June 2011, revised international aviation fuel standards officially allow commercial airlines to blend conventional jet fuel with up to 50 percent biofuels. The renewable fuels "can be blended with conventional commercial and military jet fuel through requirements in the newly issued edition of ASTM D7566, Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons".
said in a 2006 column:
Thought on how to grapple with this unsustainable growth, and even to reduce air travel from its present level in order to avoid dangerous climate change
, seems to be most prominent in the UK. Although the specifics differ globally, this work in the UK is likely to be widely applicable.
Personal choices and social pressure:
The German video short The Bill explores how travel and its impacts are commonly viewed in everyday developed-world life, and the social pressures that are at play. Using the concept of "love miles" George Monbiot also delved into this topic in his above 2006 column:
British writer George Marshall has investigated common rationalizations that act as barriers to making personal choices to travel less, or to justify recent trips. In an informal research project, "one you are welcome to join," he says, he deliberately steered conversations with people who are attuned to climate change problems to questions about recent long-distance flights and why the travel was justified. Reflecting on actions contrary to their beliefs, he noted, "(i)ntriguing as their dissonance may be, what is especially revealing is that every one of these people has a career that is predicated on the assumption that information is sufficient to generate change -- an assumption that a moment’s introspection would show them was deeply flawed."
Business and professional choices:
Ending incentives to fly—frequent flyer programs:
Over 130 airlines have "frequent flyer programs"
based at least in part on miles, kilometers, points or segments for flights taken. Globally, such programs included about 163 million people as reported in 2006. These programs benefit airlines by habituating people to air travel and, through the mechanics of partnerships with credit card companies and other businesses, in which high profit margin revenue streams can amount to selling free seats for a high price. The only part of United Airlines
business that was making money when the company filed for bankruptcy in 2002 was its frequent flyer program.
Concerning business travel, "The ease of international air travel and the fact that, for most of us, the costs are met by our employers, means that ... globe trotting conference travel is often regarded as a perk of the job." However, the perk usually is not only the business trip itself, but also the frequent flyer points which the individual accrues by taking the trip, and which can be redeemed later for personal air travel. Thus a conflict of interest
is established, whereby bottom-up pressure may be created within a firm or government agency for travel that is really not necessary. Even when such conflict is not a motivation, the perk of frequent flyer miles can be expected to lead in many cases to personal trips that would not be taken if a ticket had to paid for with personal funds.
By just using an airline-sponsored credit card to pay one's household expenses, personal or business bills, or even bills expensible to an employer, frequent flyer points can be racked up quickly. Thus, free travel—for which the individual has to pay nothing extra—becomes a reality. Across society, this too can be expected to lead to much air travel—and greenhouse gas emissions—that otherwise would not occur.
Several studies have contemplated the elimination of frequent flyer programmes (FFPs), on the grounds of anti-competitiveness, ethics, conflict with society's overall well-being, or climate effects. There is a record of governments disallowing or banning FFPs and of industry players requesting bans. Denmark did not allow the programs until 1992, then changing its policy because its airlines were disadvantaged. In 2002, Norway banned domestic FFPs in order to promote competition among its airlines. In the U.S. in 1989, a vice president of Braniff "said the government should consider ordering an end to frequent-flyer programs, which he said allow unfair competition."
A Canadian study said that because of competition no airline could unilaterally end its FFP, but that a national government could use its regulatory power to end the programs broadly, which in Canada's case would also require North American-wide cooperation. In further analysis, a Scandinavian study which recommended an end to frequent flyer plans said, "the only possible way of prohibiting FFPs successfully now that they have spread from the US to Europe to the Far East would be to do so on a global basis. The basis exists: it could be done by the World Trade Organization." A recent study which surveyed frequent flyers in the U.K. and Norway, looked into behavioral addition to frequent flying and the "flyer's dilemma" of the conflict between "the social and personal benefits of flying and air travel's impact on climate change." It concluded that:
Potential for governmental constraints on demand:
One means for reducing the environmental impact of aviation is to constrain demand for air travel, through increased fares in place of expanded airport capacity. Several studies have explored this:
, neither are the non-CO2 climate effects. In place of agreement, Governments agreed to work through the International Civil Aviation Organization
(ICAO) to limit or reduce emissions and to find a solution to the allocation of emissions from international aviation in time for the second round of Kyoto in 2009 in Copenhagen
; however, that conference failed reach an agreement on these emissions.
system to meet CO2 emissions reduction objectives. Guidelines for the adoption and implementation of a global scheme are currently being developed, and will be presented to the ICAO Assembly in 2007, although the prospects of a comprehensive inter-governmental agreement on the adoption of such a scheme are uncertain.
Within the European Union
, however, the European Commission
has resolved to incorporate aviation in the European Union Emissions Trading Scheme (ETS). A new directive has been adopted by the European Parliament in July 2008 and approved by the Council in October 2008. It will enter into force on 1 January 2012.
, the use of aviation biofuel
s and route optimisation reduces the impact of aviation on greenhouse gas emissions.
Organisations
News
Aircraft engine
An aircraft engine is the component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines...
s emit noise
Noise pollution
Noise pollution is excessive, displeasing human, animal or machine-created environmental noise that disrupts the activity or balance of human or animal life...
, particulates, and gases which contribute to climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
and global dimming
Global dimming
Global dimming is the gradual reduction in the amount of global direct irradiance at the Earth's surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has been estimated to be of the order of a 4%...
. Despite emission reductions from automobiles and more fuel-efficient and less polluting turbofan
Turbofan
The turbofan is a type of airbreathing jet engine that is widely used for aircraft propulsion. A turbofan combines two types of engines, the turbo portion which is a conventional gas turbine engine, and the fan, a propeller-like ducted fan...
and turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
engines, the rapid growth of air travel
Air travel
Air travel is a form of travel in vehicles such as airplanes, helicopters, hot air balloons, blimps, gliders, hang gliding, parachuting or anything else that can sustain flight.-Domestic and international flights:...
in recent years contributes to an increase in total pollution attributable to aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
. In the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions from aviation increased by 87% between 1990 and 2006.
There is an ongoing debate about possible taxation of air travel and the inclusion of aviation in an emissions trading
Emissions trading
Emissions trading is a market-based approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants....
scheme, with a view to ensuring that the total external costs of aviation are taken into account.
Climate change
Like all human activities involving combustionCombustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...
, most forms of aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
release carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
(CO2) and other greenhouse gases into the Earth's atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
, contributing to the acceleration of global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
and (in the case of CO2) ocean acidification
Ocean acidification
Ocean acidification is the name given to the ongoing decrease in the pH and increase in acidity of the Earth's oceans, caused by the uptake of anthropogenic carbon dioxide from the atmosphere....
.
In addition to the CO2 released by most aircraft in flight through the burning of fuels such as Jet-A
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...
(turbine aircraft) or Avgas
Avgas
Avgas is an aviation fuel used to power piston-engine aircraft. Avgas is distinguished from mogas , which is the everyday gasoline used in cars and some non-commercial light aircraft...
(piston aircraft), the aviation industry also contributes greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions from ground airport
Airport
An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...
vehicles and those used by passengers and staff to access airports, as well as through emissions generated by the production of energy used in airport buildings, the manufacture of aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
and the construction of airport infrastructure.
While the principal greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emission from powered aircraft in flight is CO2, other emissions may include nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
and nitrogen dioxide
Nitrogen dioxide
Nitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...
, (together termed oxides of nitrogen or NOx), water vapour and particulates
Particulates
Particulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...
(soot and sulfate particles), sulfur oxides, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
(which bonds with oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
to become CO2 immediately upon release), incompletely burned hydrocarbons, tetra-ethyl lead
Tetra-ethyl lead
Tetraethyllead , abbreviated TEL, is an organolead compound with the formula 4Pb. An inexpensive additive, its addition to gasoline from the 1920's allowed octane ratings and thus engine compression to be boosted significantly, increasing power and fuel economy...
(piston aircraft only), and radicals such as hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
, depending on the type of aircraft in use.
The contribution of civil aircraft-in-flight to global CO2 emissions has been estimated at around 2%. However, in the case of high-altitude airliners which frequently fly near or in the stratosphere
Stratosphere
The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
, non-CO2 altitude-sensitive effects may increase the total impact on anthropogenic (man-made) climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
significantly.
Mechanisms
Subsonic aircraft-in-flight contribute to climate change in four ways:Carbon dioxide (CO2)
- CO2 emissions from aircraft-in-flight are the most significant and best understood element of aviation's total contribution to climate change. The level and effects of CO2 emissions are currently believed to be broadly the same regardless of altitude (i.e. they have the same atmospheric effects as ground based emissions). In 1992, emissions of CO2 from aircraft were estimated at around 2% of all such anthropogenic emissions, and that year the atmospheric concentration of CO2 attributable to aviation was around 1% of the total anthropogenic increase since the industrial revolution, having accumulated primarily over just the last 50 years.
Oxides of nitrogen (NOx)
- At the high altitudes flown by large jet airliners around the tropopauseTropopauseThe tropopause is the atmospheric boundary between the troposphere and the stratosphere.-Definition:Going upward from the surface, it is the point where air ceases to cool with height, and becomes almost completely dry...
, emissions of NOx are particularly effective in forming ozoneOzoneOzone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
(O3) in the upper troposphereTroposphereThe troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....
. High altitude (8-13km) NOx emissions result in greater concentrations of O3 than surface NOx emissions, and these in turn have a greater global warming effect. The effect of O3 concentrations are regional and local (as opposed to CO2 emissions, which are global).
- NOx emissions also reduce ambient levels of methaneMethaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
, another greenhouse gas, resulting in a climate cooling effect. But this effect does not offset the O3 forming effect of NOx emissions. It is now believed that aircraft sulfurSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
and water emissions in the stratosphereStratosphereThe stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
tend to deplete O3, partially offsetting the NOx-induced O3 increases. These effects have not been quantified. This problem does not apply to aircraft that fly lower in the troposphere, such as light aircraft or many commuter aircraft.
Water vapor (H2O)
- One of the products of burning hydrocarbons in oxygen is water vapour, a greenhouse gas. Water vapour produced by aircraft engines at high altitude, under certain atmospheric conditions, condenses into droplets to form Condensation trails, or contrails. Contrails are visible line clouds that form in cold, humid atmospheres and are thought to have a global warming effect (though one less significant than either CO2 emissions or NOx induced effects) SPM-2. Contrails are extremely rare from lower-altitude aircraft, or from propellerPropeller (aircraft)Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...
-driven aircraft or rotorcraft.
- Cirrus cloudCirrus cloudCirrus clouds are atmospheric clouds generally characterized by thin, wispy strands, giving them their name from the Latin word cirrus meaning a ringlet or curling lock of hair...
s have been observed to develop after the persistent formation of contrails and have been found to have a global warming effect over-and-above that of contrail formation alone. There is a degree of scientific uncertainty about the contribution of contrail and cirrus cloud formation to global warming and attempts to estimate aviation's overall climate change contribution do not tend to include its effects on cirrus cloud enhancement.
Particulates
- Least significant is the release of soot and sulfate particles. Soot absorbs heat and has a warming effect; sulfate particles reflect radiation and have a small cooling effect. In addition, they can influence the formation and properties of clouds. All aircraft powered by combustion will release some amount of soot.
CO2 emissions per passenger kilometre
Emissions of passenger aircraft per passenger kilometre vary extensively, according to variables such as the size of the aircraft, the number of passengers on board, and the altitude and distance of the journey as the practical effect of emissions at high altitides may be greater than those of emissions at low altitudes. Some representative figures for CO2 emissions are provided by LIPASTO's survey of average direct emissions (not accounting for high-altitude radiative effects) of airliners expressed as CO2 and CO2 equivalent per passenger kilometre:- Domestic, short distance, less than 463 km (288 mi): 257 g/km CO2 or 259 g/km (5.6 oz/mile) CO2e
- Domestic, long distance, greater than 463 km (288 mi): 177 g/km CO2 or 178 g/km (3.7 oz/mile) CO2e
- Long distance flights: 113 g/km CO2 or 114 g/km (2.5 oz/mile) CO2e
For perspecitve, per passenger a typical economy-class New York to Los Angeles round trip produces about 715 kg (1574 lb) of CO2, but is equivalent to 1,917 kg (4,230 lb) of CO2 when the high altitude “climatic forcing” effect is taken into account. Within the categories of flights above, emissions from scheduled jet flights are substantially higher than turboprop or chartered jet flights. The emissions above are similar to a four-seat car with one person on board; however, flying trips often cover longer distances than would be undertaken by car, so the total emissions are much higher. About 60% of aviation emissions arise from international flights, and these flights are not covered by the Kyoto Protocol and its emissions reduction targets.
Per passenger kilometre, figures from British Airways suggest carbon dioxide emissions of 0.1 kg for large jet airliners (a figure which does not account for the production of other pollutants or condensation trails).
Total climate effects
In attempting to aggregate and quantify the total climate impact of aircraft emissions the Intergovernmental Panel on Climate ChangeIntergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...
(IPCC) has estimated that aviation’s total climate impact is some 2-4 times that of its direct CO2 emissions alone (excluding the potential impact of cirrus cloud enhancement). This is measured as radiative forcing
Radiative forcing
In climate science, radiative forcing is generally defined as the change in net irradiance between different layers of the atmosphere. Typically, radiative forcing is quantified at the tropopause in units of watts per square meter. A positive forcing tends to warm the system, while a negative...
. While there is uncertainty about the exact level of impact of NOx and water vapour, governments have accepted the broad scientific view that they do have an effect. Globally in 2005, aviation contributed "possibly as much as 4.9% of radiative forcing." UK government policy statements have stressed the need for aviation to address its total climate change impacts and not simply the impact of CO2.
The IPCC has estimated that aviation is responsible for around 3.5% of anthropogenic climate change, a figure which includes both CO2 and non-CO2 induced effects. The IPCC has produced scenarios estimating what this figure could be in 2050. The central case estimate is that aviation’s contribution could grow to 5% of the total contribution by 2050 if action is not taken to tackle these emissions, though the highest scenario is 15%. Moreover, if other industries achieve significant cuts in their own greenhouse gas emissions, aviation’s share as a proportion of the remaining emissions could also rise.
Future emission levels: improved efficiencies vs. the trend in increased travel and freight
Even though there have been significant improvements in fuel efficiency through aircraft technology and operational management as described here, these improvements are being continually eclipsed by the increase in air traffic volume.Continual Increases in Travel & Freight
From 1992 to 2005, passenger kilometers increased 5.2% per year, even with the disruptions of 9/11 and two significant wars. Since the onset of the current recession:
- "During the first three quarters of 2010, air travel markets expanded at an annualized rate approaching 10%. This is similar to the rate seen in the rapid expansion prior to the recession. November’s results mean the annualized rate of growth so far in Q4 drops back to around 6%. But this is still in line with long run rates of traffic growth seen historically. The level of international air travel is now 4% above the pre-recession peak of early 2008 and the current expansion looks to have further to run."
- "Air freight reached a new high point in May (2010) but, following the end of inventory restocking activity, volumes have slipped back to settle at a similar level seen just before the onset of recession. Even so, that means an expansion of air freight during 2010 of 5-6% on an annualized basis – close to historical trend. With the stimulus of inventory restocking activity removed, further growth in air freight demand will be driven by end consumer demand for goods which utilize the air transport supply chain. ... The end of the inventory cycle does not mean the end of volume expansion but markets are entering a slower growth phase."
In a 2008 presentation and paper Professor Kevin Anderson
Kevin Anderson (scientist)
Professor Kevin Anderson is the Deputy Director of the Tyndall Centre for Climate Change Research; holds a joint chair in Energy and Climate Change at the School of Mechanical, Aerospace and Civil Engineering at the University of Manchester and School of Environmental Sciences at University of East...
of the Tyndall Centre for Climate Change Research
Tyndall Centre
The Tyndall Centre for Climate Change Research is an organisation based in the United Kingdom that brings together scientists, economists, engineers and social scientists to 'research, assess and communicate from a distinct trans-disciplinary perspective, the options to mitigate, and the...
showed how continued aviation growth in the UK threatens the ability of that nation to meet CO2 emission reduction goals necessary to contain the century-end temperature increase to even 4 or 6C°. (See also: the 4 Degrees and Beyond International Climate Conference (2009)
4 Degrees and Beyond International Climate Conference
The 4 Degrees and Beyond International Climate Conference, subtitled Implications of a Global Climate Change of 4+ Degrees for People, Ecosystems and the Earth-system, was held 28-30 September 2009 at Oxford, United Kingdom. Implications of...
and its proceedings.) His charts show the projected domestic aviation carbon emission increase for the UK as growing from 11 MT in 2006 to 17 MT in 2012, at the UK's historic annual emission growth rate of 7%. Beyond 2012 if the growth rate were reduced to 3% yearly, carbon emissions in 2030 would be 28 MT, which is 70% of the UK's entire carbon emissions budget that year for all sectors of society. This work also suggests the foreseeable future which confronts many other nations that have high dependency on aviation. "Hypermobile Travelers," an academic study by Stefan Gössling
Stefan Gössling
Stefan Gössling, born 1970, is a Professor Professor of Tourism at the School of Business and Economics, Linnaeus University, Kalmar, Sweden. Dr...
et al. (2009) in the book "Climate Change and Aviation," also points to the dilemma caused by the increasing hypermobility of air travelers
Hypermobility (travel)
The term hypermobility in regard to travelers arose around 1980 and is a concept that has increased in useage since the early 1990s: Damette ; Hepworth and Ducatel ; Whitelegg ; Lowe ; van der Stoep ; Shields ; Cox ; Adams ; Khisty and Zeitler ; Gössling et al. ; and Mander & Randles...
both in particular nations and globally.
Increasing efficiencies of aircraft and their operation
Modern jet aircraft are significantly more fuel efficient (and thus emit less CO2 in particular) than 30 years ago. Moreover, manufacturers have forecast and are committed to achieving reductions in both CO2 and NOx emissions with each new generation of design of aircraft and engine. Thus, the accelerated introduction of more modern aircraft represents an opportunity to reduce emissions per passenger kilometre flown. However, aircraft are major investments that endure for many decades, and replacement of the international fleet is therefore a long-term proposition which will greatly delay realizing the climate benefits of many kinds of improvements. Engines can be changed at some point, but nevertheless airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...
s have a long life.
Other opportunities arise from the optimisation of airline timetables, route networks and flight frequencies to increase load factors (minimise the number of empty seats flown), together with the optimisation of airspace. However, these are each one-time gains, and as these opportunities are successively fulfilled, diminishing returns can be expected from the remaining opportunities.
Another possible reduction of the climate-change impact is the limitation of cruise altitude of aircraft. This would lead to a significant reduction in high-altitude contrails for a marginal trade-off of increased flight time and an estimated 4% increase in CO2 emissions. Drawbacks of this solution include very limited airspace capacity to do this, especially in Europe and North America and increased fuel burn because jet aircraft are less efficient at lower cruise altitudes.
While they are not suitable for long-haul or transoceanic flights, turboprop aircraft used for commuter flights bring two significant benefits: they often burn considerably less fuel per passenger mile, and they typically fly at lower altitudes, well inside the tropopause, where there are no concerns about ozone or contrail production.
Alternative fuels
Some scientists and companies such as GE Aviation and Virgin Fuels are researching biofuelBiofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
technology for use in jet aircraft. As part of this test Virgin Atlantic Airways
Virgin Atlantic Airways
Virgin Atlantic Airways Limited is a British airline owned by Sir Richard Branson's Virgin Group and Singapore Airlines...
flew a Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
from London Heathrow Airport to Amsterdam Schiphol Airport on 24 February 2008, with one engine burning a combination of coconut oil
Coconut oil
Coconut oil is an edible oil extracted from the kernel or meat of matured coconuts harvested from the coconut palm . Throughout the tropical world, it has provided the primary source of fat in the diets of millions of people for generations. It has various applications in food, medicine, and industry...
and babassu oil
Attalea speciosa
Attalea speciosa is a palm native to the Amazon Rainforest region in South America...
. Greenpeace
Greenpeace
Greenpeace is a non-governmental environmental organization with offices in over forty countries and with an international coordinating body in Amsterdam, The Netherlands...
's chief scientist Doug Parr said that the flight was "high-altitude greenwash
Greenwash
Greenwashing , or "green sheen", is a form of spin in which green PR or green marketing is deceptively used to promote the perception that a company's policies or products are environmentally friendly.-Usage:...
" and that producing organic oils to make biofuel
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
could lead to deforestation and a large increase in greenhouse gas emissions. Also,
the majority of the world's aircraft are not large jetliners but smaller piston aircraft, and with major modifications many are capable of using ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
as a fuel. Another consideration is the vast amount of land that would be necessary to provide the biomass feedstock needed to support the needs of aviation, both civil and military.
In December 2008 an Air New Zealand
Air New Zealand
Air New Zealand Limited is the national airline and flag carrier of New Zealand. Based in Auckland, New Zealand, the airline operates scheduled passenger flights to 26 domestic destinations and 24 international destinations in 15 countries across Asia, Europe, North America and Oceania, and is...
jet completed the world's first commercial aviation test flight partially using jatropha
Jatropha
Jatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female...
-based fuel. Jatropha, used for biodiesel, can thrive on marginal agricultural land where many trees and crops won't grow, or would produce only slow growth yields. Air New Zealand set several general sustainability criteria for its Jatropha, saying that such biofuels must not compete with food resources, that they must be as good as traditional jet fuels, and that they should be cost competitive with existing fuels.
In January 2009, Continental Airlines
Continental Airlines
Continental Airlines was a major American airline now merged with United Airlines. On May 3, 2010, Continental Airlines, Inc. and UAL, Inc. announced a merger via a stock swap, and on October 1, 2010, the merger closed and UAL changed its name to United Continental Holdings, Inc...
used a sustainable biofuel to power a commercial aircraft for the first time in North America. This demonstration flight marks the first sustainable biofuel demonstration flight by a commercial carrier using a twin-engined aircraft, a Boeing 737-800
Boeing 737 Next Generation
The Boeing 737 Next Generation, commonly abbreviated as Boeing 737NG, is the name given to the -600/-700/-800/-900 series of the Boeing 737 after the introduction of the -300/-400/-500 Classic series. They are short- to medium-range, narrow-body jet airliners...
, powered by CFM International CFM56-7B engines. The biofuel blend included components derived from algae and jatropha plants.
One fuel biofuel alternative to avgas
Avgas
Avgas is an aviation fuel used to power piston-engine aircraft. Avgas is distinguished from mogas , which is the everyday gasoline used in cars and some non-commercial light aircraft...
that is under development is Swift Fuel. Swift fuel was approved as a test fuel by ASTM International
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
in December 2009, allowing the company to continue their research and to pursue certification testing. Mary Rusek, president and co-owner of Swift Enterprises predicted at that time that "100SF will be comparably priced, environmentally friendlier and more fuel-efficient than other general aviation fuels on the market".
As of June 2011, revised international aviation fuel standards officially allow commercial airlines to blend conventional jet fuel with up to 50 percent biofuels. The renewable fuels "can be blended with conventional commercial and military jet fuel through requirements in the newly issued edition of ASTM D7566, Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons".
Reducing air travel
As George MonbiotGeorge Monbiot
George Joshua Richard Monbiot is an English writer, known for his environmental and political activism. He lives in Machynlleth, Wales, writes a weekly column for The Guardian, and is the author of a number of books, including Captive State: The Corporate Takeover of Britain and Bring on the...
said in a 2006 column:
- "Aviation has been growing faster than any other source of greenhouse gases. Between 1990 and 2004, the number of people using airports in the UK rose by 120%, and the energy the planes consumed increased by 79%. Their carbon dioxide emissions almost doubled in that period - from 20.1 to 39.5 megatonnes, or 5.5% of all the emissions this country produces. Unless something is done to stop this growth, flying will soon overwhelm all the cuts we manage to make elsewhere. But the measures the government proposes are useless."
Thought on how to grapple with this unsustainable growth, and even to reduce air travel from its present level in order to avoid dangerous climate change
Avoiding Dangerous Climate Change
The related terms "avoiding dangerous climate change" and "preventing dangerous anthropogenic interference with the climate system" date to 1995 and earlier, in the Second Assesment Report of the International Panel on Climate Change and previous science it cites.In 2002, the United Nations...
, seems to be most prominent in the UK. Although the specifics differ globally, this work in the UK is likely to be widely applicable.
Personal choices and social pressure:
The German video short The Bill explores how travel and its impacts are commonly viewed in everyday developed-world life, and the social pressures that are at play. Using the concept of "love miles" George Monbiot also delved into this topic in his above 2006 column:
- "When it comes to flying, there seems to be no connection between intention and action. This is partly because the people who are most concerned about the inhabitants of other countries are often those who have travelled widely. ... When you form relationships with people from other nations, you accumulate what I call "love miles": the distance you must travel to visit friends and partners and relatives on the other side of the planet. If your sister-in-law is getting married in Buenos Aires, it is both immoral to travel there, because of climate change, and immoral not to, because of the offence it causes. ... Who could be surprised to discover that "ethical" people are in denial about the impacts of flying?"
British writer George Marshall has investigated common rationalizations that act as barriers to making personal choices to travel less, or to justify recent trips. In an informal research project, "one you are welcome to join," he says, he deliberately steered conversations with people who are attuned to climate change problems to questions about recent long-distance flights and why the travel was justified. Reflecting on actions contrary to their beliefs, he noted, "(i)ntriguing as their dissonance may be, what is especially revealing is that every one of these people has a career that is predicated on the assumption that information is sufficient to generate change -- an assumption that a moment’s introspection would show them was deeply flawed."
Business and professional choices:
- "With most international conferences having hundreds if not thousands of participants, and the bulk of these usually travelling by plane, conference travel is an area where significant reductions in air-travel-related GHG emissions could be made. ... This does not mean non-attendance." (Reay, 2004) For example, by 2003 Access Grid technologyAccess GridAccess Grid is a collection of resources and technologies that enables large format audio and video based collaboration between groups of people in different locations. The Access Grid is an ensemble of resources, including multimedia large-format displays, presentation and interactive...
has already been successfully used to host several international conferences, and technology has likely progressed substantially since then.
Ending incentives to fly—frequent flyer programs:
Over 130 airlines have "frequent flyer programs"
Frequent flyer program
A frequent flyer program is a loyalty program offered by many airlines. Typically, airline customers enrolled in the program accumulate frequent flyer miles corresponding to the distance flown on that airline or its partners. There are other ways to accumulate miles...
based at least in part on miles, kilometers, points or segments for flights taken. Globally, such programs included about 163 million people as reported in 2006. These programs benefit airlines by habituating people to air travel and, through the mechanics of partnerships with credit card companies and other businesses, in which high profit margin revenue streams can amount to selling free seats for a high price. The only part of United Airlines
United Airlines
United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...
business that was making money when the company filed for bankruptcy in 2002 was its frequent flyer program.
Concerning business travel, "The ease of international air travel and the fact that, for most of us, the costs are met by our employers, means that ... globe trotting conference travel is often regarded as a perk of the job." However, the perk usually is not only the business trip itself, but also the frequent flyer points which the individual accrues by taking the trip, and which can be redeemed later for personal air travel. Thus a conflict of interest
Conflict of interest
A conflict of interest occurs when an individual or organization is involved in multiple interests, one of which could possibly corrupt the motivation for an act in the other....
is established, whereby bottom-up pressure may be created within a firm or government agency for travel that is really not necessary. Even when such conflict is not a motivation, the perk of frequent flyer miles can be expected to lead in many cases to personal trips that would not be taken if a ticket had to paid for with personal funds.
By just using an airline-sponsored credit card to pay one's household expenses, personal or business bills, or even bills expensible to an employer, frequent flyer points can be racked up quickly. Thus, free travel—for which the individual has to pay nothing extra—becomes a reality. Across society, this too can be expected to lead to much air travel—and greenhouse gas emissions—that otherwise would not occur.
Several studies have contemplated the elimination of frequent flyer programmes (FFPs), on the grounds of anti-competitiveness, ethics, conflict with society's overall well-being, or climate effects. There is a record of governments disallowing or banning FFPs and of industry players requesting bans. Denmark did not allow the programs until 1992, then changing its policy because its airlines were disadvantaged. In 2002, Norway banned domestic FFPs in order to promote competition among its airlines. In the U.S. in 1989, a vice president of Braniff "said the government should consider ordering an end to frequent-flyer programs, which he said allow unfair competition."
A Canadian study said that because of competition no airline could unilaterally end its FFP, but that a national government could use its regulatory power to end the programs broadly, which in Canada's case would also require North American-wide cooperation. In further analysis, a Scandinavian study which recommended an end to frequent flyer plans said, "the only possible way of prohibiting FFPs successfully now that they have spread from the US to Europe to the Far East would be to do so on a global basis. The basis exists: it could be done by the World Trade Organization." A recent study which surveyed frequent flyers in the U.K. and Norway, looked into behavioral addition to frequent flying and the "flyer's dilemma" of the conflict between "the social and personal benefits of flying and air travel's impact on climate change." It concluded that:
Potential for governmental constraints on demand:
One means for reducing the environmental impact of aviation is to constrain demand for air travel, through increased fares in place of expanded airport capacity. Several studies have explored this:
- The UKUnited KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
study Predict and Decide - Aviation, climate change and UK policy, notes that a 10% increase in fares generates a 5% to 15% reduction in demand, and recommends that the British government should manage demand rather than provide for it. This would be accomplished via a strategy that presumes "… against the expansion of UK airport capacity" and constrains demand by the use of economic instruments to price air travel less attractively.
- A study published by the campaign group Aviation Environment FederationAviation Environment FederationThe Aviation Environment Federation is the principal UK non-profit making organisation concerned with the environmental effects of aviation. These range from aviation noise issues associated with small airstrips or helipads to the contribution of airline emissions to global warming...
(AEF) concludes that by levying £9 billion of additional taxes, the annual rate of growth in demand in the UK for air travel would be reduced to 2%.
- The ninth report of the House of Commons Environmental Audit Select CommitteeEnvironmental Audit Select CommitteeThe Environmental Audit Select Committee is a select committee of the House of Commons in the Parliament of the United Kingdom. The remit of the committee is to examine how government department's policies and programmes will affect both the environment and sustainable development.-Membership:As of...
, published in July 2006, recommends that the British government rethinks its airport expansion policy and considers ways, particularly via increased taxation, in which future demand can be managed in line with industry performance in achieving fuel efficiencies, so that emissions are not allowed to increase in absolute terms.
- In his conclusion, after considering alternative fuels, better efficiency not expanding air fields and terminals, etc., Monbiot wrote:
Kyoto Protocol
Greenhouse gas emissions from fuel consumption in international aviation, in contrast to those from domestic aviation and from energy use by airports, are not assigned under the first round of the Kyoto ProtocolKyoto Protocol
The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change , aimed at fighting global warming...
, neither are the non-CO2 climate effects. In place of agreement, Governments agreed to work through the International Civil Aviation Organization
International Civil Aviation Organization
The International Civil Aviation Organization , pronounced , , is a specialized agency of the United Nations. It codifies the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth...
(ICAO) to limit or reduce emissions and to find a solution to the allocation of emissions from international aviation in time for the second round of Kyoto in 2009 in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
; however, that conference failed reach an agreement on these emissions.
Emissions trading
As part of that process the ICAO has endorsed the adoption of an open emissions tradingEmissions trading
Emissions trading is a market-based approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants....
system to meet CO2 emissions reduction objectives. Guidelines for the adoption and implementation of a global scheme are currently being developed, and will be presented to the ICAO Assembly in 2007, although the prospects of a comprehensive inter-governmental agreement on the adoption of such a scheme are uncertain.
Within the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, however, the European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
has resolved to incorporate aviation in the European Union Emissions Trading Scheme (ETS). A new directive has been adopted by the European Parliament in July 2008 and approved by the Council in October 2008. It will enter into force on 1 January 2012.
Mitigation
Increased fuel efficiencyFuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is...
, the use of aviation biofuel
Aviation biofuel
Aviation biofuel is a biofuel used for aircraft. Aviation biofuel is widely considered by the aviation industry to be one of the primary means by which the industry can reduce its carbon footprint. After a multi-year technical review from aircraft makers, engine manufacturers and oil companies,...
s and route optimisation reduces the impact of aviation on greenhouse gas emissions.
Noise
Aircraft noise is seen by advocacy groups as being very hard to get attention and action on. The fundamental issues are increased traffic at larger airports and airport expansion at smaller and regional airports.See also
- Air transport and the environment (United Kingdom)Air transport and the environment (United Kingdom)The environmental impact of aviation in the United Kingdom is increasing due to the increasing demand for air travel in the country. In the past 25 years the UK air transport industry has seen sustained growth, and the demand for passenger air travel in particular is forecast to increase more than...
- Aviation Environment FederationAviation Environment FederationThe Aviation Environment Federation is the principal UK non-profit making organisation concerned with the environmental effects of aviation. These range from aviation noise issues associated with small airstrips or helipads to the contribution of airline emissions to global warming...
, a UK focused non-profit direct action group - Biofuels
- Climate changeClimate changeClimate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
- EcoJet
- Electric aircraft
- Flying MattersFlying MattersFlying Matters was a pro-aviation coalition in the United Kingdom. Members included tourist organisations, airlines, aerospace manufacturers, trade associations, airport operators, growers and others. Formed in June 2007, they have issued briefings, press releases, lobbied Members of Parliament and...
, a pro-aviation coalition in the United Kingdom - Global warmingGlobal warmingGlobal warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
- Hydrogen powered aircraft
- Hypermobility (travel)Hypermobility (travel)The term hypermobility in regard to travelers arose around 1980 and is a concept that has increased in useage since the early 1990s: Damette ; Hepworth and Ducatel ; Whitelegg ; Lowe ; van der Stoep ; Shields ; Cox ; Adams ; Khisty and Zeitler ; Gössling et al. ; and Mander & Randles...
- Plane MadPlane MadPlane Mad is an Irish direct action group that campaigns against the aviation industry's contribution to climate change. It was established in 2007, and is a sister group to the British group Plane Stupid. It is a non-hierarchical organisation...
(direct action group) - Sustainable biofuels
External links
- Air travel, climate change, and green consumerism
- Centre for Air Transport and the Environment
- Commercial aviation industry environmental initiatives
- Climate Change Denial blog Exploring the psychology of climate change denial.
- Efficient Aviation: The Sky’s the Limit Eight ways to cut fuel consumption, Allianz Knowledge, June 2008
- European Federation for Transport and Environment (T&E) 'Clearing the Air: The Myth and Reality of Aviation and Climate Change'
- EU Parliament to Tighten Airline Emissions Rules
- Flight Emission Calculator
- Partnership for AiR Transportation Noise and Emissions Reduction
- Sustainable Aviation
- The Dreadful Cost of Flying
Organisations
- Stop Flying
- Manchester Climate Action
- Plane Stupid
- Flight Pledge
- GreenSkies Alliance
- AirportWatch
- Air Transport Action Group
- Aviation Environment Federation
News