Hi,
Looks like they are broadly speaking comarable. This claims to show the general picture:
http://www.grida.no/publications/other/ipcc%5Fsr/?src=/climate/ipcc/aviation/125.htm
(but it doesn't appear to add weighting to the additional problems of CO2 at high altitude)
One transatlantic round trip would probably churn out more CO2 per head than most people generate from a year of car use....

>How does that compare to the greenhouse gases if all passengers on a single plane were driving in autos instead?
>
>>Agnes,
>>
>>I didn't check the atom balance, good catch. But the CO2 balance is correct and that's all that's relevant in this case. Agreed that the 4.0L/km/passenger average might be off by a few percent if it's weighted more on longer range flights. But Airbus claims much better fuel economy so I stuck with the more conservative value.
>>
>>>>kerosene combustion reaction: C12H28 + 37/2 O2 -> 12C02 + 13H20
>>>
>>>where is the single H2 where do you get a half O2?
>>>
>>>28 Atoms H on the left does not equal 13H2 equal 26 Atoms on the right
>>>
>>>it must be
>>>
>>>C12H28 + 37/2 O2 -> 12C02 + 13H20 +H2
>>>
>>>but this sounds not likely, why shouldn't the free H2 not react? If there is not enough oxygene I always thought it would react with the hydrogen rather then carbon.
>>>
>>>or
>>>
>>>C12H28 + 19 O2 -> 12C02 + 14H20
>>>
>>>If you use a more complex equation where the H2 goes to something else you need to put this into the equation and its remnants into acount to the rest of your view.
>>>
>>>Short range flights consume more fuel then average. No idea how much. But just consider the repeated acceleration, climbing and lower flight altitude.
>>>
>>>Universe is non linear.