Conspiracy theories can be stubborn, particularly in the echo chamber of the internet.
One persistent belief in some quarters is that the government — or business, perhaps — is deploying a fleet of jet aircraft to spray chemicals into the sky to control the population, food supply or other things.
As evidence, they point to what they call “chemtrails,” which are more commonly known as contrails, or condensation trails, produced at high altitudes as water vapor in jet engine exhaust condenses and freezes.
Adding fuel to the chemtrails theory is the fact that there are a few legitimate reasons for atmospheric spraying — “seeding” clouds to make rain, for example — and in recent years there has been some research on the idea of spraying chemicals as a potential way to fight global warming.
But now, scientists have become more organized in their efforts to shoot down the idea, conducting a peer-reviewed study in Environmental Research Letters that debunks chemtrails supporters’ claims.
The goal, the researchers say, is not so much to change the minds of hard-core believers, but to provide a rebuttal — the kind that would show up in a Google search — to persuade other people to steer clear of this idea.
Steven J. Davis, a climate scientist at the University of California, Irvine, said he had the idea for the study after a conversation with a salesman at a mattress store.
When the man found out what he did for a living, Dr. Davis said, “he had very serious questions about what we were going to do about the chemtrails problem.”
Dr. Davis said that when he got home, he searched the internet for peer-reviewed studies on the conspiracy theory, but found none.
The theory has been popularized on websites that display photographs of contrails but are described instead as chemtrails that persist in the atmosphere and contain harmful chemicals like strontium, barium and aluminum.