The observation appears valid: the cause (fundamental reason) is theorized to be high altitude clouds enhanced/formed by the aircraft vapor trails increasing cloud cover -> increasing reflections from the atmosphere.
On a normal day, there would be a few percent more clouds up high than on a day without jet traffic. Thus, if there were no jets over a three day period, temps should rise a little bit because more energy is absorbed, not reflected by clouds.
They did measure average temps over the US in the three days after 9/11 and temps did go up by a .25 degree (rem - check actual value).
Thus, to combat global warming, increase jet traffic. Or increase contrail formation by seeding or aerosol injection.
A theory is not the production of evidence of a cause.
In every sense, from “chem trails” to “CO2” there is frequent unproven application of mindless zero-sum affects for things in an atmosphere of knowledge that KNOWS it is not true (zero sum affects) and KNOWS that we know far less than what we do know about the total dynamic complexity of the atmosphere.
A theory and a statistical correlation are not evidence of a “cause”, only actual, on hand evidence of an input and ALL affects resulting from it can any verifiable cause be attributed to that input and that input alone.
What were ALL the other climate elements and their attributes and their behaviors and their values - over the U.S. - over those three days? Not known or even stated to be known.
Is it without reason and without evidence, when there has been no great change in airline activity over the US during a three day period, for the upper atmosphere to have registered a 0.25 degree change over that period. IN FACT IT IS NOT. Ergo - correlation is not causation.
The mean average temperate is not a statement of a day to day constant. In some small measure, to some small degree, the only constant is that it changes.
Hey! Those contrails are from the evil government jets spraying the population with mind control drugs. Everyone knows that. Just turn on your AM transistor radio and listen to the talk shows late at night. There are "scientists" that call in and admit it.
(snicker)