Effects of air traffic on climate
This possibility was briefly discussed in the first edition of Hot Talk, Cold Science (HTCS) (see Fig. 19, pg. 54), with emission peaking at about 30 km and latitude ~30Ndeg. However, it has not yet been detected.
I anticipate that as air traffic grows, there will be more "contrails," cirrus clouds, made up of ice crystals from the condensation of water vapor in the cold upper atmosphere.
As such clouds covered the sky, they would block the escape of thermal radiation to space. As they cover the "atmospheric window" from 8 to 12 micro-meters (microns), they would cause intense warming of the surface. This warming has nothing to do with CO2.
The effect can be easily checked by observing down-welling radiation, from the ground, with a spectrometer — i.e., the U of Wisc–ARM station would observe the effect and could issue a warning.
Another, more difficult way to verify the effect would be to stop all jet traffic for a day or two, such as happened after the September 11, 2001 terror attack.
In critiquing the "nuclear winter" (see Singer in "Meteorology and Atmospheric Physics," 1988, pp. 228–239) hypothesis, I have calculated such a warming from the atomic explosions on the ground that carry water vapor and dust into the stratosphere.
I concluded then that a nuclear war would initially lead to intense warming — a "nuclear summer" — caused by this super-greenhouse mechanism (Singer, "Re-analysis of "Nuclear Winter," in Meteorology & Atmospheric Physics, 1988, pp. 228-239).