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Quantifying expert consensus against the existence of a 'chemtrails' conspiracy
Environmental Research Letters | August 10, 2016

Nearly 17% of people in an international survey said they believed the existence of a secret large-scale atmospheric program (SLAP) to be true or partly true. SLAP is commonly referred to as “chemtrails” or “covert geoengineering,” and has led to a number of websites (e.g., Global SkyWatch) purported to show evidence of widespread chemical spraying linked to negative impacts on human health and the environment.

To address these claims, we surveyed two groups of experts—atmospheric chemists with expertise in condensation trails and geochemists working on atmospheric deposition of dust and pollution—to scientifically evaluate for the first time the claims of SLAP theorists.

Results show that 76 of the 77 scientists (98.7%) that took part in this study said they had not encountered evidence of a SLAP, and that the data cited as evidence could be explained through other factors, including well-understood physics and chemistry associated with aircraft contrails and atmospheric aerosols.

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 science that can inform public discourse.

Shearer et al., 2016
Selected Press: NY Times, Forbes, Vice, Slate, Science
Figure 2 from Shearer et al., 2016

Presented with four different images of trails behind aircraft (a-d), experts uniformly responded that a secret, large-scale atmospheric spraying program (SLAP) was not the most parsimonious explanation for the depicted phenomena (pie charts). In each case, the stacked bars show the experts’ most common alternative explanations.

Image in Figure 2a from Shearer et al., 2016

Photograph obtained from Global SkyWatch website as posted by user "bornfree" and used here assuming Fair Use (see disclaimer below). Originally captioned: ""Two Contrail planes alongside one Chemtrail plane. These pictures were taken in Tucson Arizona in 2011."

Image from Figure 2b from Shearer et al., 2016

Photograph copyright owned by Forrest M. Mims III and used with permission. Originally published in 2004.

Image from Figure 2c from Shearer et al., 2016

Photograph obtained from website as posted by "Josef P. Willems" and used here assuming Fair Use (see disclaimer below). Originally captioned: "KLM Flight 9165 from Amsterdam to Dubai, cruising at FL350, seen from 1000 ft above. Maybe the largest trails I've ever seen..." Taken May 21, 2002

Image from Figure 2d from Shearer et al., 2016

Photograph obtained from website, photographer unknown and used here assuming Fair Use (see disclaimer below). Originally captioned: "战机大规模演习后空中流下的尾迹。" (Contrails behind fighter jets in the large scale exercise)"


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