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Air Travel and Climate Change
How do greenhouse gas emissions from flying compare with emissions from other forms of transport, like driving? Compared to other modes of transport, such as driving or taking the train, travelling by air has a greater climate impact per passenger kilometer, even over longer distances (see graph below). It’s also the mode of freight transport that produces the most emissions. CLICK HERE FOR LARGE IMAGE
When jet fuel is burned, the carbon in the fuel is released and bonds with oxygen (O2) in the air to form carbon dioxide (CO2). Burning jet fuel also releases water vapour, nitrous oxides, sulphate, and soot. Aircraft emissions trigger the formation of contrails (condensation trails), and contribute to the formation of cirrus clouds. A special characteristic of aircraft emissions is that most of them are produced at cruising altitudes high in the atmosphere. Scientific studies have shown that these high-altitude emissions have a more harmful climate impact because they trigger a series of chemical reactions and atmospheric effects that have a net warming effect. The IPCC, for example, has estimated that the climate impact of aircraft is two to four times greater than the effect of their carbon dioxide emissions alone.
Contrails are the long plumes of exhaust that can be seen in the sky behind airplanes. They consist primarily of water droplets and ice, and are formed when water vapour released from burning jet fuel condenses at higher altitudes. Contrails may stay in the sky for many hours, and can spread 2 kilometres wide before dispersing. The net effect of these contrails is to trap heat that would otherwise escape from the earth, which contributes to global warming. Studies have shown that night flights have the strongest warming impact, because during the daytime contrails actually reflect some sunlight away from the earth.
Not much, unfortunately. Countries with national emissions targets under the Kyoto Protocol, like Canada, are only required to account for emissions from domestic flights. Emissions from international flights are not counted. And very little has been done to actually limit these emissions. To date the only formal plan to control and reduce international aviation emissions is being developed within the European Union (EU).
Right now there is no climate-friendly alternative to the kerosene fuel burned by airplanes, and there is no indication that solar or hydrogen-powered aircraft can be expected anytime soon. In terms of efficiency, it appears that improvements in current aircraft technology have nearly reached their limit, and further significant fuel efficiency gains will only come from the development of radically new airplane designs and systems. The time, cost and coordinated effort it would take to develop and test such designs, and then phase them into the world’s fleets of aircraft, make this unlikely to happen anytime soon, and an impractical solution for the urgent problem of climate change. In reality, the small, incremental gains that we can reasonably expect in aircraft fuel efficiency will be eclipsed by the projected growth in the industry.
Because the climate impacts of air transportation are at present not adequately regulated under national or international laws, the onus is on individuals and businesses to limit their flying unless absolutely necessary. This needn’t be as drastic as it sounds:
If you do have to fly:
In Fall 2006 the David Suzuki Foundation purchased videoconferencing equipment for its Vancouver office. We already rely on phone conferences for many of our meetings, and look for ways to minimize travel to conferences, training sessions and other functions. We currently purchase high quality carbon offsets for all Foundation air travel. We are also taking an office-wide look at our air travel requirements, seeking further reduction opportunities.
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Air Travel
security, travelling to and from the airport, and sitting in those tiny seats. Most of us live in places that tourists from elsewhere visit, so take a holiday in your hometown or region and find out what it has to offer.
