Ladies and Gentleman I pose an honest and interesting question, to those of you hopefully closer to the core of this question... (NASA hopefully) because I'm very tired of being hit by the left wing media spewing-on about airline pollution in the upper atmospheres. It contradicts what I heard from one of the NASA Global Express Atmosphere Test pilots I spoke to face to face in Christchurch / EnZed, many years ago.
This is the latest slanted story on what I speak of and it lacks... everything, basically!
Scram jets' fuel requirements and upper atmosphere propulsion diminishes the higher you get doesn't it?
In discussions with the NASA pilot I'd spoken of previously, their findings were (being at the last section of their global trip I believe) findings were that jet engine emissions above the Tropopause/ jetstreams were found to have been beneficial, while those below where otherwise.
Can someone with expertise please swipe the politics into the bin and give the true Facts? ("Handing over")