If you replace 1 old aircraft, that emit 100 units of pollution into the atmosphere, with 5 modern aircraft, that emit 30 units of pollution into the atmosphere, then you are still releasing more pollution into the atmosphere than you were back when you were using that single aircraft (5 x 30 = 150). So the point that CoolP makes is still valid. More pollution IS being emitted into the atmosphere today, than it was many years ago. The only difference is that it takes more aircraft to do it.

I'm not using exact figures because I don't know what they really are.