Years ago, I attended a climate science conference at University College London. While the specifics of the meeting are lost to me, the day remains vivid. Upon arrival, I encountered demonstrators outside, a familiar sight at such events that typically draw both supporters and skeptics of climate change.

Initially, the protesters conducted themselves peacefully, and I chose to enter the conference. Around mid-morning, however, they disrupted the lecture hall, heckling the speaker before storming the stage with their slogans and signs.

The protesters were unlike any I had encountered. Instead of being traditional climate activists or skeptics, one was a proponent of a conspiracy theory called chemtrails. In essence, this theory posits that the condensation trails (contrails) left by aircraft contain harmful substances deliberately released to manipulate the weather, poison people, or serve other sinister purposes.

This is untrue. Contrails are simply long streaks of ice crystals created when water vapor in engine exhaust freezes in the cold air at cruising altitudes. While they typically dissipate quickly, under certain conditions they can linger for hours, forming what conspiracy theorists label as chemtrails.

Like many conspiracy theories, this one carries elements of truth. Although contrails may look stunning against a summer sky, they nevertheless contribute to environmental damage.

It’s well-established that airplanes have an adverse effect on the climate. Burning aviation fuel represents about 2.5% of global greenhouse gas emissions. Yet, contrails and contrail-induced clouds are categorized as “aeronautical non-carbon dioxide.” The climatic effects might be equally or even more severe.

This is attributable to basic physics. Similar to greenhouse gases, ice crystals in cirrus clouds trap infrared radiation escaping from Earth, generating a warming effect. They also reflect incoming sunlight, counteracting this effect. Ultimately, though, they contribute to global warming.

In reality, the impact of contrails on climate is not completely understood. Last year, NASA acknowledged this knowledge gap and asked the National Academies of Sciences, Engineering, and Medicine to investigate the climatic repercussions of contrails and suggest research methodologies.

Recently published, the report states that contrails might contribute to warming potentially exceeding that of aviation fuel, though significant uncertainty remains. Fortunately, options exist to mitigate this impact, including altering fuel formulations, refining engine designs, and rerouting flights to avoid areas conducive to contrail formation.

The report does not mention chemtrails, which is sensible. While the panel might have considered debunking this unfounded conspiracy theory, they opted not to give it publicity. Regardless, the report is unlikely to effect change, especially under the current US administration. Donald Trump’s administration has shown a tendency towards anti-science and conspiracy-driven climate skepticism, making addressing contrails a low priority. Significant regulatory changes regarding the airline and fossil fuel industries are necessary, so don’t expect immediate action.

I suspect that the airline and fossil fuel sectors silently welcome chemtrail theorists; their distractions divert attention from the true implications of contrails on climate.

Instead, the report will likely collect dust, while another report on chemtrails gets commissioned. Reports associate President Trump’s Secretary of Health and Human Services, Robert F. Kennedy Jr., with the conspiracy as part of an unscientific initiative to make America healthy again. Despite the absence of credible evidence, the notion persists.

Earlier this year, while enjoying a sunny afternoon, I had a conversation with my neighbors. “Have a nice day,” I said. “If they weren’t here, they will be,” he replied, gesturing skyward at intersecting contrails. He, too, is a climate change skeptic.

The chemtrail conspiracy is inherently frustrating—wholly futile. Despite their lack of scientific understanding, conspiracy theorists seem to think their beliefs will yield results. They are intrinsically distrustful of corporate and governmental authority and care about both environmental and human welfare. Yet, their actions only draw attention away from genuine protests and misallocate it toward unfounded notions.

The UCL meeting ultimately succumbed to continuous protests. If the dissenters believed they had triumphed, they were mistaken. Climate change remains a grave threat—chemtrails do not exist.