Journal Article 1 Mention
Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program
Christine Shearer•2016
Mick WestKen Caldeira
Top 11% · 89th Percentile
28 citations · Global and Planetary Change
Open Access

TLDR

Nearly all surveyed specialists found no evidence that airplanes are secretly spraying chemicals on a large scale. They said the trails and test results presented as proof had other explanations, including ordinary flight conditions and flawed sample collection.

Summary

1 Study Aim

The authors aimed to assess claims of a secret large-scale atmospheric spraying program (SLAP), often called “chemtrails.” They asked whether specialists had encountered evidence of such a program and how they interpreted photographs of aircraft trails and chemical test results. The researchers wanted to find out whether specialists saw proof of secret spraying.

2 Study Design

The authors surveyed two expert groups: atmospheric scientists specializing in condensation trails (visible trails formed behind aircraft) and geochemists (scientists who study Earth’s chemical composition). They identified experts through highly cited research papers and invited 171 trail specialists and 190 atmospheric-deposition specialists, who study material settling from air onto Earth. Forty-nine trail specialists and 28 deposition specialists completed separate surveys. The surveys asked about possible evidence, showed photographs or sample analyses, and assessed sample-collection advice. The researchers asked specialists to review the trails, test results, and collection methods.

3 Findings

The study reports that 76 of 77 respondents had never encountered evidence of a secret large-scale atmospheric spraying program (SLAP). All 49 trail specialists said ordinary trail formation best explained the four photographs, citing factors such as moisture and aircraft altitude. Most deposition specialists also rejected the chemical test results as proof; some said more information was needed, and others found the readings typical of dust or sediment. Most disagreed with online sampling advice, warning that it could contaminate samples. The authors conclude that the evidence reviewed does not support secret spraying and recommend careful attention to real pollution concerns. Specialists found no convincing proof of secret spraying, and poor testing methods could mislead people.

Abstract

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 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 expertize 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.

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