Chemtrail conspiracy theories: Here’s why RFK Jr. is watching the skies

This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.

A conspiracy theory that airplanes are leaving nefarious “chemtrails” in their wake due to a sinister government plot has been given fresh impetus in the US amid a swirl of concerns and confusion about proposals to geoengineer a response to the climate crisis.

State legislation to ban what some lawmakers call chemtrails has been pushed forward in Tennessee and, most recently, Florida. Meanwhile, Robert F. Kennedy Jr., who has expressed interest in the conspiracy theory on social media and his podcast, is set to be at the heart of Donald Trump’s new administration following his nomination as health secretary.

“We are going to stop this crime,” Kennedy, who is known for his contrarian stances on vaccines and offshore wind farms, wrote about chemtrails on X in August. The former Democrat turned Trump ally said on his podcast last year that it was “kind of frightening to think that somebody may be putting large amounts of bioavailable aluminum into the environment, spraying it in microscopic particulates from airplanes.”

Believers of the chemtrails conspiracy theory contend that the white lines traced in the sky behind aircraft contain toxic chemicals that are released to achieve a devious end, such as mass sterilization or mind control.

This theory, which has no evidence to support it, has been put forward at various times since the 1990s despite being repeatedly debunked. Now, scientists are faced with a resurgent focus on chemtrails amid a related, more substantive, debate over whether actual modifications to the Earth’s atmosphere should be made in a desperate attempt to slow global heating.

Interest in chemtrails “bubbles up every once in a while and the hurricanes and weather modification kind of brings it up to the floor again,” said David Fahey, director of the chemical sciences laboratory at the National Oceanic and Atmospheric Administration (NOAA), in reference to two recent major hurricanes—Helene and Milton—that some figures, including Republicans, claimed were somehow steered by the federal government’s meddling with the weather.

“The misinformation is abundant,” said Fahey, who has spent several decades, on and off, fielding questions about chemtrails. There was no orchestrated weather modification conducted by NOAA, Fahey said, and even experimenting with such a thing would be a “big step for our agency and one that we are not quite prepared to do at the moment, and maybe our agency shouldn’t do it.”

Are chemtrails real?

No. The white plumes seen from the rear of aircraft are more aptly called condensation trails, or contrails. They are essentially condensed water vapor from a plane’s exhaust that, in cold air temperatures at high altitudes, form as ice crystals that look like visible clouds.

A survey of leading atmospheric scientists in 2016 found there was no evidence of a secret spraying program that would form these contrails. This research led to backlash from conspiracy theorists, with Ken Caldeira, a climate scientist who led the study, saying that he received death threats.

“I felt like it was a risk to my personal safety,” he said. “People have bought into this false narrative. We’re now seeing a worrying resurgence of conspiracy theories in general, from chemtrails to vaccines. There’s a detachment from facts and rational analysis.”

In fact, contrails do contribute to a form of “weather modification”—just not the sort envisioned by the conspiracy-minded. The plumes often grow into hazy cirrus clouds that trap heat and add to the greenhouse effect that is warming up the world, mostly via the burning of fossil fuels.

“As with many conspiracy theories, there is some truth to it in that aircraft are releasing particles and affecting the Earth’s climate system,” said Caldeira, who is involved in an effort to get airlines to reduce their contrail output. “But this is because of unintended consequences of the fossil fuel airline system, rather than some nefarious secret reason.”

Are any other weather modifications being conducted?

There is a confusing stew of different processes, or just theories, with different goals that have been variously called weather modification, solar geoengineering, or solar radiation management.

These often get mixed up and mistaken for secret government conspiracies. Cloud seeding, for example, involves dispersing tiny particles into clouds to spur the formation of ice crystals that trigger rain or snow. Utah routinely does this to increase snowfall rates and authorities there have had to point out that this is not connected to chemtrails.

A separate debate has stirred in recent years as to whether governments, or even wealthy individuals, should intervene to slow dangerous global heating by spraying reflective substances such as sulphur into the stratosphere in order to deflect sunlight from further warming the Earth.

Noaa is setting up a system to monitor the stratosphere that could act as an “early warning” system for such activities. A US startup has offered “credits” for people to buy to help cool the world’s fever but as yet there has been no activity detected on a significant scale that would alter the climate.

“There are some demonstration projects,” said Fahey. “But in terms of large-scale airplanes taking material to the stratosphere, I’m not aware of anything, certainly in our country.”

Can solar engineering help solve the climate crisis?

This year is set to be the hottest ever recorded globally, the latest in a string of hot years that are pushing the average temperature to the point it looks certain to breach the internationally agreed threshold designed to avoid catastrophic heatwaves, droughts, floods, and other worsening climatic disasters.

The failure of governments to stem this crisis has led to calls for more drastic interventions, like solar geoengineering, to curb the global temperature rise. Last year, the White House released a congressionally mandated report on how a research program into solar geoengineering would work.

Such plans are highly controversial, however, with some scientists and environmental groups warning that meddling with the Earth’s thermostat could have unintended consequences such as altering monsoon seasons.

There are also concerns about the lack of global governance around adding substances to our shared atmosphere, the potential for a huge temperature whiplash should the continual addition of sulphur via planes stop for any reason, and the danger that geoengineering would distract from the primary task of cutting planet-heating emissions. Efforts by some researchers to run experiments on solar modification have been met with protests.

As the world continues to heat up, though, the conversation around solar geoengineering, and related conspiracies, is unlikely to abate. “I think it’s increasingly on the agenda of people who are wondering where is our climate going and how might we influence where it’s going,” said Fahey.