In a paper publish in Environmental Research letters, August 2016, 77 scientists with expertise in atmospheric science and geochemistry were asked to give their expert opinions regarding the most common claims of evidence put forward by proponents of the "chemtrail" or "covert geoengineering" theory (referred to in the paper as a "secret large-scale atmospheric program (SLAP)". The evidence being photos of trails left by planes, and chemical analyses of air, soil, and water. The scientists overwhelming rejected the idea that the photos and tests were evidence of a secret spraying program. All of the atmospheric scientists and all but one of the geochemists saw nothing suspicious about the proffered evidence. The photos were all identified as contrails, and the chemical analyses were generally identified as expected results due to normal variation and poor testing methodology.
Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program
Chemtrail believers frequently show the same kinds of evidence over and over. Because of the fringe nature of this belief many scientists simply ignore the issue and the claims of evidence are likewise ignored. Since the claims are often only refuted by online lay skeptics the believers in the theory think they may have more validity than they actually do. So by having a large number of actual experts examine the evidence and give their professional opinion, a more accurate assessment of the evidence can be given to the believers.
And it is a large number of experts, have a look at the list of atmospheric scientists polled:
- Andrew Carleton, Penn State University
- Andrew Heidinger, National Oceanic and Atmospheric Administration
- Andrew Heymsfield, National Center for Atmospheric Research
- Andrew J Weinheimer, National Center for Atmospheric Research
- Brian A Ridley, National Aeronautics and Space Administration
- Bruce Anderson, National Aeronautics and Space Administration
- Bryan Baum, University of Wisconsin-Madison
- Charles A Brock, National Oceanic and Atmospheric Administration
- Charles E Kolb, Aerodyne Research
- Christine Fichter, German Aerospace Center (DLR)
- Christos Zerefos, University of Athens
- Cynthia Twohy, NorthWest Research Associates
- Darrel Baumgardner, Droplet Measurement Technologies
- David Doelling, National Aeronautics and Space Administration
- David Kratz, National Aeronautics and Space Administration
- David Lee, Manchester Metropolitan University
- David Lewellen, West Virginia University
- David J Travis, University of Wisconsin-Whitewater
- Donald P Garber, National Aeronautics and Space Administration
- Eleftheratos Konstantinos, University of Athens
- Gaby Radel, University of Reading
- Guy Febvre, Observatory of Atmospheric Physics at Clermont-Ferrand
- Hartmut Grassl, Max Planck Institute for Meteorology
- Jack Dibb, University of New Hampshire
- Karen Rosenlof, National Oceanic and Atmospheric Administration
- Klaus Gierens, German Aerospace Center (DLR)
- Larry Miloshevich, Milo Scientific
- Markus Garhammer, Ludwig-Maximilians-University
- Matthias Tesche, Stockholm University
- Michael Ponater, German Aerospace Center (DLR)
- Michael Prather, University of California, Irvine
- Otto Klemm, University of Muenster
- Patrick Minnis, National Aeronautics & Space Administration
- Piers Forster, University of Leeds
- R Paul Lawson, Stratton Park Engineering Company
- Rabi Palikonda ,National Aeronautics & Space Administration
- Reinhold Busen, German Aerospace Center (DLR)
- Robert Sausen, Institute of Atmospheric Physics
- Robert Talbot, University of Houston
- Ru-Shan Gao, National Oceanic and Atmospheric Administration
- Sonia M Kreidenweis, Colorado State University
- Stephan Bakan, Max Planck Institute for Meteorology
- Tatiana Khokhlova, University of Washington
- Thilo Stilp European, Aviation Group for Occupational Safety and Health
- Tove Svenby Norwegian, Institute for Air Research
- Ulrich Schumann Institute, of Atmospheric Physics
- Ulrike Burkhardt, German Aerospace Center (DLR)
- Volker Grewe, Institute of Atmospheric Physics
- William L Smith, National Aeronautics and Space
The photos were chosen to illustrate the most common type of photographic evidence presented by chemtrail believers:
a) Planes leaving long trails where seemingly adjacent planes leave no trails
b) Trails from planes that leave gaps
c) Trails that seem to come from the whole wing surface, and exhibit a spectrum of colors
d) Multiple persistent trails curving and criss-crossing the sky.
b) Trails from planes that leave gaps
c) Trails that seem to come from the whole wing surface, and exhibit a spectrum of colors
d) Multiple persistent trails curving and criss-crossing the sky.
(unfortunately since Environmental Research Letters is a UK publication, they were not able to display all the photos due to the more restrictive UK copyright laws. I have reproduced them all in the copy of the figure above).
As well as simply giving a yes/no answer on if they thought the photos were evidence of covert geoengineering, the scientists were asked to explain what they thought was going on in the photo. For example the photo (b) with the gap in the trail (credit: Forest M. Mims III)

The atmospheric scientists were all asked a simple question:
"What is the most likely reason there is a gap in this trail?"
A variety of answers were given, for example:
- "A local area of the upper troposphere where the temperature or the humidity (or both) are below the threshold values needed for a persisting contrail (e.g., due to locally sinking air at that altitude, which warms up and dries out the air)."
- "A dry spot."
- "Water vapor fields are not homogeneous or uniform. Part of the contrail is in a region where the relative humidity is less than 100% with respect to ice and the crystals are evaporating"
- "Aircraft passing through local turbulence condition (strong upwinds?) leading to a rapid break-up of the vortex in the area. Likely to accelerate also the break up of the vortex."
- "Atmospheric variability: In that area the air is probably not moist enough, not a ice supersaturated region ."
These various answers were manually grouped into the four most common variants, along with an "other" category, and the results were graphed:
The results were similar for the other three photos, as seen in the top image.
The scientists were also asked "Could you provide a citation to a publication describing the mechanisms that most likely account for the phenomena shown in the photo?", and a wide variety of scientific papers were cited with the most common reference for photo (b) being Schumann’s ‘On conditions for contrail formation from aircraft exhausts’ (1996) and Schumann’s ‘Formation, properties, and climate effects of contrails’ (2005), both cited by 6% of experts.
The geochemists survey was slightly less clear cut, which probably reflects the more ambiguous nature of the data, and lack of information regarding collection procedures. Three chemical analyses were presented, all of which we picked because they have been continually cited by chemtrail believers for several years, and are still in use as of today. Unfortunately they were not reproduced in the paper, so I will reproduce them here.
Analysis a, pond sediment
Analysis b, airborne particulates:
Analysis c, Snow Surface
With the results:
The question with the most consesus is the pond sample, which was featured in the film "What In The World Are They Spraying?" in 2010. The scientists were asked:
"Do you think the most parsimonious explanation of these results involve the existence of a secret large-scale atmospheric spraying program?
If yes, why? If not, how would you interpret these results?"
If yes, why? If not, how would you interpret these results?"
As with the contrail photos the answer was generally "no" and there were a variety of interpretations which were grouped as seen above. Some sample responses:
- "It looks like about 5 grams of average soil or desert dust in a liter of sludge, quite reasonable."
- "I would compare the concentration of Al, Ba and Sr to that in local sources (e.g., local streams, rocks/sediments/soil, discharges from local facilities)."
- "The elemental concentrations are consistent with silicate mineral dissolution. The Al concentration could be due to colloidal Al. Nothing unusual here, No red flags from this data. More really needs to be known; i.e what is the pH and O2 status of the pond, also what is the DOC. Hard to say much from 3 concentration numbers"
- "Most likely anthropogenic pollution (industrial or municipal); any more detailed interpretation would require knowledge of the environmental context"
- "All three of these elements are major constituents of crustal material. The concentrations reported for the three elements are much less than what is present in average upper continental crust. The results report an aluminum concentration of 375000ppb which is less than 0.04%. Average continental crust is 7.96% aluminum (Wedepohl, 1995). All three elements are reported at values two-three orders of magnitude less than crustal values."
The confusion about what the test actually represented was shared by other scientists, some of whom took the comparison against the MCL levels at face value, but others correctly identified the problems, like with the second sample:
- "As in the last example, the units reported are not directly interpretable. Are the results reported as concentration in air, or as concentration in a lab prepared solution? There are many possible sources of these metals as airborne particulates, especially in an urban environment."
- "The concentrations per unit mass look like average soil or desert dust. The MCL values are not relevant, and look to be based on drinking water standards"
- "Presence of particles from aeolian [wind] erosion?"
- "Firstly, all three elements are common constituents of crustal material. This figure does not provide adequate information regarding collection methods, location, analytical methods, etc for one to make any judgement regarding their validity whatsoever. Further, the MCL values quoted are for contaminants in water not air."
- "Probably from mineral particles."
In addition the scientists were asked to give their assessment of the water testing procedure that geoengineringwatch.org used at the time for analysis (a).
Progress seemed very slow, as the main authors had other projects to work on. With chemtrails being a bit of a fringe subject it seemed difficult for some people in the academic community to take it seriously, and there were occasional reports of people being highly surprised at the very idea of such a study, including some of the experts who were surveyed (or who were asked, but declined).
The surveying was completed early 2015, but again other commitments kept the main authors from working much on the project until later in the year. I contributed a little to the wording and proof reading, but the vast bulk of the work collating the results, writing the paper, and creating figures was done by Christine and Steve. The paper was completed in early 2016, and published on August 10th 2016.
The big question of course is: will it help? Time will tell. There's some debate regarding fringe subjects as to whether they should be addressed at all. If you take conspiracy theories seriously enough to write a peer reviewed paper rebutting them, then does it actually make the theory more plausible for some people? Will media coverage of the paper actually just lead to more people being exposed to the chemtrail theory? These are genuine concerns.
My hope is that our attempt to ask neutral questions about the photos, and the honest responses of the experts, will act as a reality check. Is it really possible that these 49 listed atmospheric scientists, from all over the world, scientists who are leading experts in the field of clouds and contrails, is it possible they are all wrong? And if not (and surely nobody would argue they are all simply mistaken) then is it possible that all of them are in the employ of whoever is doing the "covert geoengineering"? And these are a representative sample of thousands of similar experts. Are they all wrong too?
Ultimately there's no convincing some people, and this study may well backfire for the hardcore conspiracist. But for people on the fence, who have not yet fallen down the rabbit hole, I think it will help them. I think this help will outweigh any harm. But time will tell.
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Here are the original sources of the photos and test results:
Plane Trails
Photo 1 - Longer and Shorter Trails
Source: http://globalskywatch.com/chemtrails/ubbthreads.php?ubb=showgallery&Number=8579#.VmW6r-MrKEI
Photographer: "Bornfree" (anonymous forum poster)
Captioned: "Two Contrail planes alongside one Chemtrail plane. These pictures were taken in Tucson Arizona in 2011."
Photo 2 - Trail with gap in between
Current Source: http://www.geoengineeringwatch.org/...ated-chemtrail-conspiracy-continues-unabated/
Previously: http://www.sas.org/tcs/weeklyIssues/2004-05-28/news2/index.html
Photographer: Forrest M. Mims III
Caption: "The break in this contrail indicates drier air than the air in which the contrail is visible."
Published in 2004
Photo 3 - Trails with color spectrum in between
Current Source: http://www.gettyimages.com/detail/photo/plane-flying-over-sea-of-clouds-leaving-high-res-stock-photography/71083312
(Previously: http://www.airliners.net/photo/KLM-Cargo/Boeing-747-206BM(SF-SUD)/0239080/L/ )
Photographer Josef P. Willems
Caption: "KLM Flight 9165 from Amsterdam to Dubai, cruising at FL350, seen from 1000 ft above. Maybe the largest trails I've ever seen..."
Photo taken May 21, 2002
Photo 4 - Swirling Trails
Source: http://war.163.com/07/1225/08/40I0FABE00011MTO.html (http://archive.today/ojnZc)
Caption: "战机大规模演习后空中流下的尾迹。" (Contrails behind fighter jets in the large scale exercise)
Photographer unknown, possible an official Chinese government photo.
Deposition
Sample 1 - Pond Sediment
Source video: "What in the World Are They Spraying",
Source: https://www.youtube.com/watch?v=mEfJO0-cTis
Time: 30:10
Sample taken 04/29/2007, Dane Wigington
Sample 2 - Air particulates
Source: http://arizonaskywatch.com/az-tests/our charts/phx_particulates_2008.htm (Crop of third image)
Sample take 05/01/2008, Air through Hepa Filter, by "Arizona Skywatch"
Sample 3 - Snow Surface
Source video: "What in the World Are They Spraying"
Source: https://www.youtube.com/watch?v=mEfJO0-cTis
Time 25:03
Sample taken 07/08/2008, Rose Taylor
Geoengineeringwatch Water Testing Procedure:
http://www.geoengineeringwatch.org/html/watertesting.html (http://archive.is/tskGA)
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