Iolar,
Although aviation may only contribute approx 3% of the global CO2 emissions, it would also seem important to measure the % contribution to C02 in the upper atmosphere since apparently that is where CO2 and other pollutants have a greater warming effect. The overall contribution to global warming from aviation pollution could be significantly higher than 3%.
Yes, but it seems there is some complexity there too. Apparently NOx emmission decay Methane. It is estimated that there is 2% less Methane due to avaition than there would otherwise be. Trop ozone (the bad kind) is created by aircraft and it is suggested that trop ozone has a greater impact than at ground level. However, sulphur and water emissions from aircraft also break down upper top and lower strat ozone (a good thing). So far no data has been gathered on the effect of this. It is worth mentioning that creation of ozone is a global impact, the effects of decay of methane and upper trop/lower strat ozone are local.
As a caveat, I don't want to give the impression I understand this, it is just what I have read!
MarKD,
Adding revenue to the equation probably doesn't tell us much because it will, theoretically, have been reduced due to the £0.99 flights, etc.
In the UK it seems there was a total of 738K movements in 2000 and 748K movements. This is a 1.4% increase and is less than the increase in PAX so I suspect there has been an increase in medium and long haul? It's an assumption I know. This seems to back up the CAA's report which suggests that LoCos have not really had as big an impact as thought on short haul trips other than to make them cheaper!!