Aviation Emissions and Climate Change – An Overview


Soaring emissions


6.3% of British CO2 emissions were from aviation in 2005.  This translates to around 13% of Britain’s climate change effect being from aviation (domestic and international).

[In fact, if UK citizens are considered, leaving the country and then returning, rather than just departing flights from UK airports, the figure is more like 16 -17% of the UK’s climate change effect being from aviation].

Aviation accounts for around 2% of the CO2 emissions globally.  That is just the CO2 only.

The UK’s aviation accounts for around 0.1% of global CO2 emissions.

Aviation contributes around 3.4% of the EU’s CO2 emissions.

50% more emissions from global aviation expected by 2020, assuming fuel efficiency improves by 50%

240.7m passengers used British airports in 2007.  In 2007 this was forecast to rise to 470m by 2030.  In January 2009 the DfT forecast UK national passenger demand, unconstrained by airport capacities, to rise from 241mppa in 2007 to 465mppa in 2030.  There are a range of forecast figures with different assumptions in the DfT January 2009 UK Passenger Demand and CO2 Forecasts.

1.2 tonnes of CO2 (approximately) are emitted for each economy passenger return London-New York flight

Sources: Department for Transport; WWF; Atmosfair
May 2009
Globally aviation now contributes 4.9% to climate change
Research from the IPCC indicates that the correct multiplier to use for CO2 emitted by planes is  x3.   See link.   They estimate that aviation accounted for 4.9% of man-made climate impacts in 2005.  This contrasts with the 2% figure that is constantly quoted by aviation lobbyists.  The figures include estimates of cirrus cloud formation
The effect of these is to increase aviation’s impacts to:
3.5% without cirrus
4.9% including cirrus








What is the real climate impact of flying and what can we do about it? (BBC info)


28th May 2009    The BBC has produced an excellent page, setting out a great deal of information on the climate change impacts of aviation.   Well worth a look. It is at: http://www.bbc.co.uk/bloom/guides/flying.shtml

Click here for more…



If flying expands as much as the UK Government predicts …

We can kiss goodbye to meeting our climate change targets. 
Increasing aviation  =  not taking climate change seriously.

Government’s climate Change Policy

By 2050 aviation could cancel out all emissions savings made from other sources

The Government has a climate change target to cut overall UK carbon emissions by 80% between 1990 and 2050.  Its own research states that this will be impossible if aviation is allowed to carry on expanding at the present rate.  For aviation to be allowed to emit as much CO2 in 2050 as it did in 2005, most other sectors of the UK will have to cut their emissions by 90% by 2050.  The independent Tyndall Centre for Climate Change Research estimated that, unless aviation emissions were controlled effectively, with business- as-usual growth, they could account for up to half of the UK’s total emissions target by 2050, cancelling out savings made by individuals and other industrial sectors.  .

Aviation’s contribution to climate change globally

Aviation is  perhaps the fast-growing contributor to human-induced global warming (with the industry growing at around 4 -5% globally)
Air travel is much more harmful to the climate than other activities which create CO2 largely because so many of their exhaust gases are emitted at a high altitude.  In 1992 aviation contributed 3% of human-induced global warming emissions, worldwide.  On present trends this could rise to 15% by 2050, maybe more.  The industry is not growing much in Europe currently due to the recession, though growth was at around 3 – 4% per year till 2007.  But in China, south east Asia, the Middle East, and other emerging nations, aviation hopes to continue growing at 4 – 5% per year.  As many other sectors de-carbonise, aviation is set to become the world’s dirtiest industry.
The computing sector and other electronics are also growing rapidly, and their emissions are also rising fast.


What % of the UK’s carbon dioxide emissions are from aviation?


The contribution of UK aviation makes to climate change is often underestimated.  There are misleading claims, such as that made by Ryanair in frequent advertisements, that aviation is only 2% of CO2 emissions. 




Government figures show that in 2005 aviation accounted for 13% of total UK climate change damage (if using a multiplier of 2).  That is an understatement because it is based on departing flights only: if the calculation is based on return flights by UK citizens in 2007 the figure would be nearer 20%.  




The figure for CO2 alone is 6.3%, but this is multiplied by 2 to take radiative forcing into account.




Using the new IPCC multiplier of 3, the climate changing effect of UK aviation is more like 19%.   See link.


Currently international aviation is not included in the UK’s climate change inventory as there is no internationally agreed method for allocating such emissions between states.


The contribution of UK aviation to climate change – briefing



Do planes produce more CO2 than other modes of transport?

Most studies show that passenger air travel produces more far more emissions than train, coach or ship.  Cars are generally shown to be higher than train, coach and ship, but usually still less than flying.
It is difficult to get exact figures, as these need to be done for one specific plane, for one specific journey – by contrast with one specific car or train, for a specific journey.  The make of plane or vehicle makes a difference, as does the load factor (how full it is), the speed and the several other variables.
As planes travel high in the atmosphere, there is an approximate doubling of climate change effect – radiative forcing – due to formation of cirrus cloud by contrails, and emission of other gases like NOx from planes. So the climate changing effect of each kilo of CO2 emitted by a jet at 35,000 feet up is about twice that of a kilo of CO2 produced at ground level.

Air travel can contribute a high proportion of any individual’s carbon footprint, as a plane journey takes so little time to cover a huge distance.  Though the emissions of CO2 per person per kilometer by plane may be only slightly worse than the same journey by car (excluding the doubling due to radiative forcinc), not many people bother to drive 10,000 miles to their holiday destination, or if they did, it would take them weeks rather than hours.  It is quick and easy by plane, with the same amount of carbon being emitted in a couple of hours of plane trip, as would take weeks by car.

One example of an attempt to get a reliable comparison is a study by CE Delft “To shift or not to shift, that’s the question: The environmental performance of the principal modes of freight and passenger transport  in the policy-making context”  (2003).

The charts on page 41 shows the emissions of CO2 per passenger kilometre.   CE Delft concludes that CO2 emissions by aircraft are anything from 3 to 10 times higher than rail for medium distance journeys of 500km. For longer journeys of 1,500km, air is a little better in terms of emission per passenger km, but still about 2 to 6 times worse than rail.


For more information, see the AirportWatch Briefing Sheets page on Climate Change   




There is a lot of useful information in the article below, from Travel Weekly, 19.1.2007 

Aviation and Climate Change – a Q&A guide

Aviation and climate change: Q&A guide
(19 January 2007)

Ryanair claims to be Europe’s “greenest, cleanest airline”. UK environment minister Ian Pearson calls the carrier “irresponsible”. Who is right?

It depends on your point of view. Ryanair operates a fleet of predominantly new aircraft that produce significantly less carbon dioxide than older models and is committed to a continual fleet renewal programme as it expands.

Aircraft fuel efficiency improved 20% in the past decade and almost 5% in the last two years, according to the International Air Transport Association, cutting emissions by a comparable amount.  The latest Boeing and Airbus models should bring further improvements.

Carriers such as Ryanair, and tour operators’ charters, also fly with more bums on seats than traditional airlines, so the emissions per passenger are lower – and area fraction of those produced by long-haul business and first-class passengers.

However, Ryanair is expanding rapidly, as are other airlines. It aims to double in size by 2012, so its total emissions will soar above improvements in fuel efficiency.

But it is Ryanair’s threat to boycott the European emissions trading scheme that provoked the environment minister’s outburst.  The Government has put all its eggs on aviation emissions in this one basket, which airlines are set to join in 2011.

They will trade carbon dioxide allowances with other industries and have to pay out if they want to expand.

Ryanair boss Michael O’Leary also delights in challenging all things green. He referred last week to “environmental hysteria” and said: “People are being scammed.” O’Leary enjoys the publicity and other carriers are happy to see him take the flak.


There are different figures for air travel’s contribution to climate warming.  What is it and what is the problem?

Aviation accounts for 2% of worldwide CO2 emissions, and 3.4% of the European Union’s.

UK air travel is responsible for 0.1% of the world’s total emissions, so airlines point out it would make little difference if everyone stopped flying.  However, flights do produce 5.5% of total UK CO2 emissions [6.3% in 2005] – reflecting the importance of Heathrow as a hub and the number of over-flights.

The problem is that air travel is the fastest-growing source of greenhouse gases and its expansion risks undermining progress in reducing emissions in other areas.

The international Kyoto Protocol of 1997 commits EU members to cut CO2 emissions by 8% below the level of 1990 by 2012.  The UKGovernment has acknowledged a need to cut emissions by 60% by 2050.  In fact, scientists suggest a 90% cut may be needed, but argue it is not achievable.

Whitehall accepts the UK cannot meet its target without cutting aircraft emissions. The Government predicts UK passenger numbers will rise to 476 million a year by 2030, taking aviation emissions to more than 4.5 times their 1990 level.   European Commission figures suggest a return, UK-Thailand flight for two produces more CO2 than the average new car will in a year.

Aircraft emit CO2, the gas responsible for about 80% of global warming.  But they also create water vapour at high altitude which may be even more damaging.  The Government suggests this may exacerbate the warming effect of air travel by a factor of 2.4, although the International Panel on Climate Change that reports to the United Nations suggests a factor of 2.7. [The UK Government now uses a figure of 1.9, while waiting for better clarity of the science].

Either way, it is a worry.


Airlines believe they are being singled out for unfair criticism. Are they right?

They have a case. Other sectors pose a much greater problem. Power stations produce 39% of EU emissions and roads are to blame for 22%.

Cutting the use of cars and trucks, switching from fossil fuels in power generation or capturing and burying CO2 from power plants would make a far bigger contribution to cutting emissions than anything airlines can do.

And there are plenty of other polluters to tackle. China is building coal-fired power stations at anastonishing rate – although its production of CO2 per person remains at one-third of that in the EU. Global deforestation is adding CO2 and reducing the amount that nature can absorb. Methane produced by cattle and seeping from rubbish dumps is exacerbating global warming, with a short-term impact many times that of CO2.

The industry has every right to be indignant about the doubling of Air Passenger Duty, which the Chancellor attempted to justify on environmental grounds.  A Treasury spokesman told Travel Weekly:  “It may provide an incentive to take holidays at home and to business travellers to consider using the train.”  Yet the Government’s Aviation White Paper of 2003 acknowledged that taxing flights would be unlikely to cut demand.

Airlines do get off lightly on tax. If aviation fuel (kerosene) was taxed at the same rate as petrol, airline fuel costs would quadruple. At the moment, kerosene is not taxed at all.

The industry should be aware it is not alone in arguing other sectors should be tackled first. European steel bosses say the same thing, pointing out EU steel plants account for just 1% of global CO2 emissions.

Tony Blair says technology is the answer. What’s wrong with that?

Technology can certainly help, as continuing improvements in aircraft engine efficiency show. However, its contribution may be much more limited in the case of flying than Blair suggests.

Despite efficiency improvements, total emissions from UK aviation rose 79% between 1990 and 2004. It is estimated the industry’s expansion will outstrip efficiencies by 3% a year for the foreseeable future, with the Government expecting UK passenger numbers to double by 2030.

The Aviation White Paper suggested a 50% reduction in CO2 emissions from aircraft may be possible by 2020. But MPs on the Commons Environmental Audit Committee described this claim as “misleading”, pointing out it depends on technologies that do not yet exist. And many airlines will continue to fly elderly, more-polluting aircraft unless they are forced to scrap them.

Developing an alternative fuel won’t be easy because of the need to operate at very low temperatures. Existing biofuels thicken when cold and would pose a safety problem. So would hydrogen. Using hydrogen as a fuel would also pose an emissions problem, since it would produce high volumes of water vapour. In its 2004 report Aviation and Global Warming (pdf) the Department for Transport concedes: “There is no viable alternative currently to kerosene.”

The Virgin Group and US space agency NASA are working on prototype aircraft that might fly far higher than today’s aircraft, in the stratosphere. But a Government Royal Commission noted scientists’ concerns that emissions at such altitude may be 5.4 times more damaging than at ground level.

What other possible solutions are there?

Air traffic control improvements could cut emissions by 10%-12%, reducing stacking over busy airports, shortening routes and allowing aircraft to come into land in a fuel-saving continuous descent approach (CDA).

Airlines could reduce emissions further by rationalising operations to cut the number of empty seats.

The European emissions trading scheme ought to play a part,although restricting it for at least the first year to flights within the EU will exclude more than 60% of aircraft emissions in Europe. Most airlines are in favour. In the words of a British Airways spokesman, a failure to include carriers in emissions trading “would be very dangerous. It would increase the political pressure to take other measures against airlines.”

However, there are doubts that it will produce any cut in emissions.  The first year of the scheme in 2005/2006 proved disappointing.  The market price of carbon collapsed and the scheme led to no overall cuts in emissions.

Carbon offsetting is becoming popular as a way for individuals to show their concern about the impact of flying on the climate. But there are limits to its effectiveness. Many schemes involve planting trees to absorb carbon dioxide, which is only absorbed for the lifetime of the tree. As forests mature they release carbon dioxide. Now a committee of MPs plans to investigate offsetting schemes to see if they really do what is claimed.

Virgin chairman Sir Richard Branson has joined environmental groups in suggesting people should not fly if there are cleaner alternative forms of travel available. “People should think twice before flying domestically,” he says.

Leave aside the fact that Virgin Trains forms an important part of Branson’s business, it is not true that railways will always be less polluting than flying. A London-Manchester flight currently produces 13 times as much CO2 per passenger as a rail journey on the same route. But faster trains will cut the savings. At 220mph, a London-Edinburgh train journey would produce more CO2 per passenger than the comparable flight.

Aren’t there still doubts about whether the world is warming, whether humans are responsible, and whether this is a bad thing?

No, the evidence on these questions is now overwhelming. The waters have been muddied by a handful of dissidents, often non-scientists, who receive substantial funds from sections of the fossil fuel industry and a sympathetic hearing from the US government.

The real arguments lie elsewhere. Climate scientists are debating how far and how fast the Earth will heat up, assuming the warming is gradual – as predicted by the IPCC. Many now argue this model is wrong and future warming will be sudden and extreme, as rising temperatures trigger changes in climate systems and release vast quantities of greenhouse gases trapped beneath oceans, ice and permafrost.

The EC warned last week: “Time is running out.”

by Ian Taylor (About this Author)
Based on a publication “Aviation and Global Climate Change” published by AEF,
Friends of the Earth, NSCA and HACAN Clearskies

People living near airports have long suffered from aircraft noise, traffic congestion
and air pollution. Indeed communities around airports have been concerned about
these issues for years. However new evidence shows that air travel is contributing
towards a far greater threat – CLIMATE CHANGE


Air travel growth + CO2 emissions

Air travel is one of the world’s fastest growing source of greenhouse gases (computing
an IT is  another)  like carbon dioxide, which cause climate change. Globally the world’s 16,000 commercial jet aircraft generate more than 700 million tonnes of carbon dioxide (CO2), the world’s major greenhouse gas, per year.   (IATA says air transport produced 649 million tonnes CO2  in 2010 (compared with 627million tonnes in 2009)   ( IATA link )

Even IATA  (The Interntional Air Transport  Association) estimates aviation is responsible for:

  • 2% of global carbon dioxide (CO2) emissions
  • 12% of CO2 emissions from all transport sources, compared to 74% from road transport
  • 3% of the total man-made contribution to climate change (other estimates put this at almost 5%, taking in to account radiative forcing). IATA then say his may grow to 5% by 2050 (which would in practice mean more like 8 -9%, depending on how aviation expands over coming decades, and how much carbon humanity produces in other ways.

(IATA link)

 Indeed aviation generates nearly as much CO2 annually as that from all human activities in Africa.

One person flying a return trip between London and New York generates between 1.5 and 2 tonnes of CO2.

The huge increase in aircraft pollution is largely due to the rapid growth in
air traffic which has been expanding at nearly two and half times average economic
growth rates since 1960.  

It is expected the number of people flying globally will virtually double (or more) over the next 15 years, to 2025.  The global aviation industry hopes for growth rates of 4% or so each  year. 

This means increasing airport capacity, more flights, more pollution and increasingly crowded airspace.


What % of the UK’s carbon dioxide emissions are from aviation?

 •  Gillian Merron’s reply in the House of Commons  2.5.2007  details below
 Government figures show that in 2005 aviation accounted for 13% of total UK climate change damage.  That is an understatement because it is based on departing flights only:  if the calculation is based on return flights by UK citizens in 2007 the figure would be nearer 20%.The figure for CO2 alone is 6.3%, but this is multiplied by 2 to take radiative forcing into account. Currently international aviation is not included in the UK’s climate change inventory as there is no internationally agreed method for allocating such emissions between states.   Gillian Merron’s reply in the House of Commons 


Aviation now contributes 4.9% of climate change worldwide

 New Report by IPCC authors.   Globally aviation contributes 3.5% if cirrus cloud is not taken into account, and 4.9% if it is.   21.5.2009   •   The same report estimates that CO2 accounts for 6.3% of total UK emissions and 9.8% of all greenhouse gases, but excluding cirrus.  Using a multiplier of 2.8 to take account of cirrus, (compared to a multiplier of 1.9 if cirrus is excluded)  the UK figure is nearer 17% than 13%.    http://aef.org.uk/?p=479


Impacts of climate change

Scientists predict surface air temperatures are likely to rise between 1 ° to
5 °C over the next century. This rate of warming is likely to be greater than at
any time in the last 10,000 years. Although the effects will vary from place to
place there is expected to be an increase in the number of very hot days and a
decrease in the number of very cold days.

  • More extreme weather events – Global warming is likely to lead to more natural disasters such as hurricanes, droughts and floods. The number of major natural disasters has increased threefold since the sixties.
  • Spread of infectious diseases -The likely increase in warmer and wetter weather could enable infectious diseases
    such as malaria and yellow fever to spread to new areas.
  • Disappearing countries – Global warming is expected to lead to a rise in sea levels of between 15 and
    95cm over the next century. Many islands and low lying coastal areas will be affected
    by rising sea levels and some island nations could disappear altogether.
  • Environmental refugees – Global warming could lead to the displacement of millions of people. Rising sea
    levels, floods and drought could make former land uninhabitable. Changing weather
    patterns could affect food crops and accelerate water shortages.
  • Effect on tourism – Ironically one of the industries most at risk from climate change is tourism.
    Many tourist destinations depend on the natural environment for their appeal to
    tourists. A study commissioned by the World Wide Fund for Nature (WWF) found many
    popular British tourist destinations would be threatened as a result of global


Aviation’s Contribution to Climate Change

In 1999 the world’s top climate scientists, the Intergovernmental Panel on Climate
Change (IPCC), published a detailed study of the impact of aircraft pollution
on our atmosphere – Aviation and the Global Atmosphere.

The report’s findings support the following:

  • Aircraft released more than 600 million tonnes of CO2 into the atmosphere in
    1990.   650 tonnes CO2 in 2010.
  • Aircraft currently cause about 3.5% of global warming from all human activities.  This could be as much as 4.9%, depending how much radiative forcing is taken into account, including the effect of cirrus cloud (contrails) produced by planes.
  • Aircraft greenhouse emissions will continue to rise and could contribute up to
    15% of global warming from all human activities within 50 years.
  • Nitrogen oxides (NOx) and water vapour from aircraft engines are important greenhouse
    gases. Water vapour contributes to the formation of contrails, often visible from
    the ground, which in turn are linked to an increase in the formation of cirrus
    clouds. Both contrails and cirrus clouds warm the Earth’s surface magnifying the
    global warming effect of aviation. Together, NOx and water vapour account for
    nearly two-thirds of aviation’s impact on the atmosphere. Hence any strategy to
    reduce aircraft emissions will need to consider other gases and not just CO2.
  • An increase in the number of supersonic aircraft could further damage the ozone
    layer as aircraft emissions of NOx deplete ozone concentrations at high altitudes,
    where these aircraft would typically fly.
  • The impacts on the global atmosphere from air travel will be concentrated over
    Europe and the USA where 70-80% of all flights occur. Hence the regional climatic
    impacts of aircraft emissions over these areas are likely to be greater than predicted
    by the IPCC report (which used global averages).


Most significantly, it concluded that improvements in aircraft and engine technology
and in air traffic management will not offset the projected growth in aircraft
emissions. That is, we need to slow the growth in air travel if we want to reduce
the growth in aircraft greenhouse gas emissions.


Is the Industry Accountable?

Emissions from international aviation are specifically excluded from the targets
agreed under the Kyoto Protocol. Instead, the Protocol invites developed countries
to pursue the limitation or reduction of emissions through the International Civil
Aviation Organisation (ICAO). To date, ICAO had not agreed any specific action,
although its environmental committee is considering the potential for using market-based

Emissions from domestic aviation are included within the targets agreed
by countries.  International air travel is not counted within country targets.  However, the UK Committee on Climate Change has advised that aviation should be taken account of within the Climate Act, even if not specifically included. They also propose that the UK’s carbon emissions from aviation should not exceed the level in 2005 by 2050. The current coalition government has not yet endorsed this fully.   (See DfT response to CCC August 2011)
UK aviation carbon dioxide emissions in 2010 were around 33.6 MtCO2, and in the central estimates, these might rise to 47.6 MtCO2 by 2030 and to 49 MtCO2 by 2050.  (The lowest estimates for CO2 are for 43.2 MtCO2 in 2030, falling to 39.6 MtCO2 in 2050.  The highest are around 60 MtCO2).  The DfT forecasts, August 2011 (173 page)  are at   UK aviation forecasts 2011 (PDF – 2000 kB) 

Despite the UK Government’s stance that aviation and its users should pay for the social and environmental costs they impose, there is no duty on kerosene.
The absence of a fuel tax, or an emissions based levy, allows airlines to charge
artificially low fares as the cost of pollution is passed on to society and not
the passenger.

The aviation sector will join the EU Emissions Trading Scheme on 1st January 2012, with all flights leaving or arriving in Europe paying for carbon permits.  Details


A New Approach

If aviation had to meet its external environmental and social costs in full,
and did not benefit from large subsidies (see AirportWatch economic briefing sheets),
the growth in demand for air travel would be much slower*. Additionally, airlines would have an added economic incentive to invest in the cleanest technology available.  

Using market-based measures to correct these market distortions is central to delivering a sustainable aviation policy.    

The role of rail over short distances (e.g. routes around 500km)

Air travel produces three to ten times more carbon dioxide per passenger then rail. Yet nearly 70% of all flights within European airspace are less than l000km long.  With over 7 ½ million flights within European airspace in 1998, there is a lot of scope to move short haul flights to rail. As well as less pollution, rail companies can boast faster check in times, city centre to city centre travel and less frequent delays than most airlines.


Advances in telecommunications can reduce the need to travel. Tele- and video-conferencing are increasingly becoming a viable alternative to flying for many business travellers.  (See WWF – One in Five challenge)

Limited value of carbon offsetting

 Voluntary carbon offsetting may help to raise consumer awareness but does not
solve the problem of greenhouse gas emissions from flying. Offsetting schemes
aim to calculate the damage caused by an individual flight and allow the traveller
to “pay” for the environmental damage by donating to organisations which will,
for example, plant trees or invest in low carbon technology in the developing
world. While offsetting sounds attractive it has several important flaws. The
different schemes come to wildly different conclusions about how much carbon any
given flight generates. Are some of them dramatically under-estimating the damage
from flying? Does offsetting amount to a token gesture to salve the conscience,
when the ethical choice is to use a different mode or not travel at all?   AirportWatch
does not recommend any particular carbon offsetting schemes. Instead it argues
for changes to tax and charging rules to achieve consistent and fair restitution
for the damage caused by flying.

For more information:

Growth Scenarios for EU & UK Aviation: contradictions with climate policy
93 page report produced by the Tyndall Centre for Climate Change for Friends of
the Earth in 2005. Shows how aviation growth could wreck UK and EU policies to
tackle climate change



Stop Climate Chaos  aims to build a massive coalition to create an irresistible
mandate for political action to stop human-induced climate change. See http://www.stopclimatechaos.org      


Related Links

Fly now, grieve later,

written by Brendon Sewill and published by the Aviation Environment Federation in 2005. Explains how to reduce the impact of air travel on climate change – a hugely readable 46 page booklet

Aviation and global climate change

Four page leaflet published in 2000 by Friends of the Earth, Aviation Environment Federation, National Society for Clean Air and HACAN Clearskies. Available in full at:


DEFRA passenger transport emission factors (June 2007) comparing emissions from forms  of transport
• How planes compare with other means of travel

Carbon offsetting