Flying beyond our means – air travel and the environment
Key text
This topic is sponsored by Dr Margaret Middleton.
With aviation’s emissions growing faster than any other transport sector our impacts on the environment are heading sky high.
In February 2008, the eyes of the aviation world were looking up in the sky at a Boeing 747 flying from London to Amsterdam.
That's because one of the four engines of the plane was flying on a mix of biofuel made from plant-based material – in this case, coconut and babassu palm oil. This test flight was hailed as the world's first commercial flight powered (partly) by biofuel, with the ultimate aim of trying to reduce carbon emissions into the atmosphere.
It might have been a public relations coup for the airline, but environmentalists criticised it as a publicity stunt saying there are only scant savings to be made using biofuels, especially if food crops are forgone to produce the fuel. Some even went so far as to label the exercise as 'high altitude greenwash'.
Then in November 2008, with much less fanfare, a small jet flew on a test flight across the United States on 100 per cent biofuel for 2,858 kilometres of the total 4,000-kilometre journey.
Greenwash or not, what both flights achieved was to focus attention on the great air race underway around the world to address the environmental effects of flying.
There are good reasons why airlines are trying to be 'greener'. With passenger numbers soaring, the emissions from domestic flights over Australia are growing faster than any other method of transport. In Australia, the number of people flying is predicted to double within the next 20 years. Over 23 million passengers – more than the country's entire population – flew on international flights in and out of Australia in the 12 months prior to August 2008. Fifty million people flew on domestic and regional flights.
Just one return trip between Sydney and London produces around 5.7 tonnes of carbon dioxide per person, about the same as the average Australian produces from their combined car and electricity emissions over an entire year.
The story is similar around the world.
Aviation contributes about 3.5 per cent of radiative forcing (global warming) and – according to the Intergovernmental Panel on Climate Change – is likely to increase to 5 per cent by 2050 for a mid range scenario, thus making air travel a significant source of man-made climate change (Box 1: What aviation emissions do).
Concerns such as these have resulted in governments, scientists and the airline industry trying to find better, 'greener' ways of flying. Alternative fuels, flight path management and more efficient plane design are just some of the areas of research (Box 2: Flying smarter).
It's also making many people and businesses re-think how and where they fly, and whether they need to fly at all (Box 3: Saving our skies – what can we do?).
The environmental effects of aviation
It's not just emissions that are the problem; aviation has a range of effects on the environment.
For starters, planes can cause considerable noise pollution, which in Australia has led to four major airports banning flights between 11pm and 6am. For local residents, at around 95 decibels every time a plane takes off it is equivalent in noise to a truck passing close by. But things are improving; the new 787 noise levels are around 10 decibels lower than the older aircraft they are replacing. According to the International Civil Aviation Organisation, noise is the biggest environmental issue with aviation for local communities. Aircraft noise affects the quality of life of residents around airports in some cases causing problems with sleep, communication, learning and even cardiovascular function.
Air pollution can also be a problem, affecting air quality for hundreds of kilometres downwind from an airport.
It's not just the planes that leave a footprint, so do the airports. There are land use, planning and ecosystem concerns at the local level as large areas of land have to be set aside for the airports and their related access roads and infrastructure.
Recent modelling by Airport Footprints Ltd for one UK airport shows that flights are responsible for 85.9 per cent of the airport's ecological footprint, with ground transport vehicles (including staff and passenger access and service vehicles and cargo trucks) responsible for another 9.5 per cent. Other demands on the environment include catering facilities, utilities such as energy and water use, built land and waste facilities.
The heavy footprint of an airport
| Sector | Percentage of airport ecological footprint (%) |
| Flights | 85.9 |
| Ground transport | 9.5 |
| Food | 0.9 |
| Utilities (energy & water) | 1.5 |
| Waste | 1.9 |
| Built land | 0.2 |
In the northern hemisphere, de-icing operations are being examined as the chemicals used to keep planes and run-ways ice-free can have harmful effects on ground water and surface water ecosystems.
Other critics add that aviation – by providing access to previously untouched parts of the world – can be responsible for pollution in previously pristine locations such as the Antarctic. And by opening the door to tourism and other developments, aviation can unwittingly help spread animal and plant diseases.
But the largest environmental impacts can't easily be seen. That's because they take place well above the Earth. According to the Australian Government Department of Climate Change, the domestic aviation industry accounted for around 6.1 million tonnes of carbon dioxide equivalent (Mt CO2-e) of greenhouse gas emissions in 2006. This represents only 7.7 per cent of all transport emissions, but aviation is one of the fastest growing contributors of greenhouse gases. While greenhouse gas emissions from transport increased by 27 per cent between 1990 and 2006, emissions from the domestic aviation industry increased more than 107 per cent.
Complicating the issue of aircraft emissions is that they have been largely unregulated. International emissions (about 50 per cent of the global total) are exempt from the Kyoto Protocol governing reductions in greenhouse gases (they will be included in the European Union's emissions trading scheme from 2012). In addition, there is no tax on airline fuel at an international level. That means there's no pool of money to help counter the adverse environmental effects of aviation, and the lack of a fuel tax can be seen as an incentive for people to travel by air, by keeping fares lower.
Peering over the horizon
Like other countries, Australia has been trying find better ways to ensure that the aviation industry reduces its footprint.
In early 2008, the Australian Government announced it would draw up a National Aviation Policy Statement, to guide the industry's growth over the next decade and beyond. This will address the environmental concerns arising from the growing number of planes in Australian skies, as well as tie in with the efforts of international bodies such as the International Civil Aviation Organisation. It will also look at the need for market-based measures such as emissions trading or carbon offset schemes in the aviation industry.
What is certain is that a range of measures will be needed – technological advances such as biofuel blends and more efficient plane design are not enough to stop the rapidly growing impact of aviation on the environment.
Boxes
1. What aviation emissions do
2. Flying smarter
3. Saving our skies – what can we do?
Related Academy Links
Nova
Carbon currency – the credits and debits of carbon emissions trading
Making our mark – ecological footprints
Quiet please! Fighting noise pollution
Local air pollution begins at home
Cleaner production – a solution to pollution?
External sites are not endorsed by the Australian Academy of Science.
Posted February 2009.