Seventeen percent of people believe that it is true or partly true that world governments currently operate a secret large-scale atmospheric spraying program (SLAP), according to an international survey conducted in 2011. They believe that a secret program of geo-engineering to prevent global warming already threatens the health of global citizens with unforeseen consequences such as air and water contamination from the spraying.
Adherents of this theory often refer to "chemtrails," a portmanteau of chemical and contrails - the name for the white lines of condensate left behind in the sky as airplanes pass by overhead. Websites such as Geoengineering Watch or Global Sky Watch present evidence supporting the chemtrails conspiracy theory, which presumes that the lines left by planes are proof of chemical aerosols being injected into jet engines as a means of pervasive delivery of these geo-engineering aerosols.
The group identified experts in the two fields of 'contrail expert' and 'atmospheric deposition expert' as those people who have co-authored one or more of the 100 most-cited papers in each area. They asked these experts if they have ever seen evidence in their careers which they believe supports the existence of SLAP. They were also asked for their expert opinions on whether the evidence presented by the chemtrails activists can be explained by natural processes (in contradiction to the contention of activists that there is no natural explanation for the phenomena, which therefore proves the existence of SLAP).
Seventy-six of 77 experts stated that they have never seen evidence of SLAP. Which naturally raises the question of what the one out of 77 has seen? The paper reports that "the evidence s/he had come across was 'high levels of atm[ospheric] barium in a remote area with standard 'low' soil barium'." Barium, along with strontium and aluminum, is often cited as a chemical contaminant which points to the "chemtrails" program.
In response to the question on natural explanations for the phenomena reported, the experts on contrails were quite clear: there are a number of explanations for the appearance of these white trails across the sky. While experts were not always in agreement on which explanation might best fit each scenario, the contrails experts were unanimous in their interpretation that the evidence can more simply be explained by natural phenomena than by "chemtrails."
Experts on atmospheric deposition answered less definitively. Over 80 percent agreed that simpler explanations than SLAP apply, but some were 'not sure' and wanted more information before making a definite conclusion. One atmospheric deposition expert did agree that SLAP is the simplest explanation for the data presented.
That said, many of the experts strongly disagreed with the sampling instructions used for collecting evidence. As any environmental scientist knows, sampling techniques can have significant impact on the analytical results. In particular, experts had problems with instructions that included the sampling of sediments in water samples. Metal contamination released by natural or industrial processes tends to concentrate in sediments. So if you want to prove that water has been contaminated, accidentally mixing a bit of sediment with the water sample is a good way to do that.
The authors say up front that,
"Our goal is not to sway those already convinced that there is a secret, large-scale spraying program—who often reject counter-evidence as further proof of their theories—but rather to establish a source of objective, peer-reviewed science that can inform public discourse in the future by seriously addressing the underlying concerns of science, governance, and public trust."
But we disagree: there are a lot of real risks in our world, and we need people with the conviction and energy of the chemtrails activists to get involved in making a difference where it counts. If you really want the government to be scared, the truth should be the first weapon of choice. This includes listening to those who have invested over 20 years of their lives studying our planet. Let's get the people with energy and commitment to force politicians to talk about the things scientists already agree pose real threats.
And let's keep looking for the real causes of the symptoms people report experiencing, rather than dismissing it as all in their heads and leaving them to come up with conspiracy theories to explain their pains. Knowing how the chemicals we use affect people and our planet must remain one of the highest priorities of our technological age.
Read more at Environmental Research Letters.