@ Anonymous Coward
'That aircraft con trails help to reduce global warming by increasing high level cloud that reflects heat.... but then again studies can show anything you want the to.'
Ummm no they don't. Contrails actually trap more heat than they reflect.
Ponater, M.; S. Marquart, R. Sausen and U. Schumann (2005). "On contrail climate sensitivity". Geophysical Research Letters 32 (10)