Are aircraft as ecologically bad as is claimed?

I've seen it claimed that a single flight by a commercial aircraft creates as much carbon dioxide as driving a car for 3 months. But the 'plane might carry 200 people for 1000 miles. Most family cars never even achieve 200,000 passenger-miles, so that means that per passenger-mile the 'plane is far more carbon efficient than a car.

Add to that the fact that aircraft produce vapour trails which encourage the creation of clouds. These clouds in turn reflect heat back into space. Did you know that the day after 9/11 the temperature over the US rose by 1 degree C due to the lack of vapour trails!. So are aircraft as bad for the environment as is currently being claimed?

For reference I have now looked up some figures. According to Wikipedia, a 747-400 uses 17 lites of fuel per kilometre. Assuming that it can carry almost 600 people, that works out at about 0.005 litres per passenger mile. By comparison a car which does 30 miles to the gallon appears to work out at aboout 0.02 litres per passenger mile if transporting 4 passengers. Please feel free to check my maths.

Airplanes are more fuel efficient than driving for trips over 200 miles.

Commercial planes burn a lot of fuel taking off and landing, and a much smaller amount while cruising. The longer the flight, the higher the efficiency. Flights under 100 miles are much worse than if the same 200 people drove their cars. 100-200 mile flights are about equal to driving. Longer flights are more efficient than driving.

only if they use a fuel that isn't

that is based on per person, not per 200 people. so you see its very bad! and dont forget the plane drops all excess fual before landing!

I think they are.

I dont know if I believe the claim that the temperature rose by 1 degree over the US after 911. How could they possibly have predicted that the temp should have been 1 degree more?

The comparison between plane and car travel is usually per person, so I think you should be doing your calculation the other way around. So if we do this with the example you have seen " I've seen it claimed that a single flight by a commercial aircraft creates as much carbon dioxide as driving a car for 3 months " then we get:

200 passengers X 3 months car carbon emissions = 1 X 600 months car emissions per flight. Thats the same emission as one person driving a car for 50 years, quite a difference.

The damage caused by the pollution being released (exhausted) from the engines at high alitude is also magnified due its proximity to the parts of the atmosphere damaged by it compared to the ground release of car exhuast.

Information from an Observer article:

The arguments against flying are compelling. One return flight to Florida produces the equivalent carbon dioxide to a year's motoring. A return flight to Australia equals the emissions of three average cars for a year. Fly from London to Edinburgh for the weekend and you produce 193kg of CO2, eight times the 23.8kg you produce by taking the train. Moreover, the pollution is released at an altitude where its effect on climate change is more than double that on the ground. (Link to source below)

And also from Airport Watch:

Air travel is the world's fastest growing source of greenhouse gases 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. 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 will virtually double over the next 15 years. This means increasing airport capacity, more flights, more pollution and increasingly crowded airspace. (Link to source below)


To go off topic slightly, in my opinion (so not fact), the pollution caused by air travel will go into steady decline within 5-15 years due to the growing scarcity of oil after peaking somewhere along that timeline. Oil prices have been on a steady rise and the "early toppers", people within the Oil Industry who believe in the lower estimates of oil reserves available, predict global oil shortages in that time leading to massive price increases which will suffocate air travel. Good source for this information is is Jeremy Leggetts - Half Gone.


If anyone see's any inconsistencies please post them, i don't like to give out wrong info.