Does the fact that aircraft exhaust increases cloud cover in the sky prove the existence of so-called chemtrails, toxic plumes emitted by airplanes embroiled in a plot to wipe out humanity? No, that's not true: Scientists are concerned about the clouds created by aviation exhaust because they trap heat inside the atmosphere and boost global warming. This is entirely unrelated to chemtrails, a conspiracy theory that scientists have debunked on several occasions.
The claim appeared in a video (archived here) on TikTok on February 25, 2024, under the caption, translated from Hungarian to English by Lead Stories staff: "Chemtrails are such a nice conspiracy theory." A caption appears at the end of the clip that reads (as translated):
So, what's this now? The atmosphere is getting warmer because of cirrus clouds, and airplanes create condensation trails/cirrus clouds? This is an acknowledgement of chemtrails!!!
Here's what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Thur Feb 29 05:54:46 2024 UTC)
The claim is based on an interview, archived in the state broadcasting archive, with Hungarian geophysicist Gábor Timár that was broadcast on Hungarian state radio on April 13, 2021, part of which is played in the video. The reporter asks Timár whether "geo-engineering," a cutting-edge scientific field that explores the possibilities for humans to manipulate weather patterns, might help reduce global warming by thinning out clouds in the stratosphere, thereby allowing more heat to escape from the Earth. Timár replies (as translated from Hungarian):
Over the past year, we humans have conducted an experiment on what would happen if there were somewhat fewer cirrus clouds, whether we wanted to or not. We did this because there was barely any air traffic after March [2020], and condensation trails [from aircraft] make up a significant part of cirrus clouds. So there were fewer of them. However, it didn't get much colder, and luckily, not warmer, either.
Timár is referring to the reduction in air traffic that occurred in 2020 due to COVID-19-related travel restrictions (archived here).
Condensation trails, or contrails for short, are water vapor emitted by aircraft that condenses into ice crystals at high altitudes. They usually dissipate quickly but can remain in the sky for up to an hour depending on temperature and humidity conditions, according to an article on the website of the U.S. Environmental Satellite, Data, and Information Service (archived here).
By trapping radiation in the Earth's atmosphere, persistent contrails contribute more to global warming than all carbon dioxide emissions from all aircraft combined, according to a 2019 study by scientists at the European Geosciences Union (archived here). The amount of radiation trapped by contrail clouds is expected to triple by 2050 due to projected growth in air travel, the study said.
The TikTok video argues that contrail clouds, as discussed by Timár, are the same thing as chemtrails. They are not. Contrails are real; chemtrails are a conspiracy theory. According to David Keath's Research Group at Harvard University (archived here):
Chemtrails refers to the theory that governments or other parties are engaged in a secret program to add toxic chemicals to the atmosphere from aircraft in a way that forms visible plumes in the sky, somewhat similar to contrails. Various different motivations for this alleged spraying are speculated, including sterilization, reduction of life expectancy, mind control or weather control.
We have not seen any credible evidence that chemtrails exist.
In 2016, open-source periodical Environmental Research Letters published a peer-reviewed survey that asked scientists whether chemtrails exist (archived here). The authors reported:
76 of the 77 scientists (98.7%) that took part in this study said they had not encountered evidence of [chemtrails], 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.
Changes in aircraft technologies may be causing contrails to persist longer than they used to, and changes in industrial development could potentially be increasing aerosol deposition in some areas. But the focus on a secret, large-scale atmospheric spraying program may be taking attention away from real, underlying problems that need addressing.
Other Lead Stories fact-checks on claims related to chemtrails can be found here.
