The majority of YouTube videos about the climate crisis oppose the scientific consensus and “hijack” technical terms to make them appear credible, a new study has found. Researchers have warned that users searching the video site to learn about climate science may be exposed to content that goes against mainstream scientific belief.

Dr Joachim Allgaier of RWTH Aachen University in Germany analysed 200 YouTube videos to see if they adhered to or challenged the scientific consensus. To do so, he chose 10 search terms:

Chemtrails

Climate

Climate change

Climate engineering

Climate hacking

Climate manipulation

Climate modification

Climate science

Geoengineering

Global warming

The videos were then assessed to judge how closely they adhered to the scientific consensus, as represented by the findings of reports by UN Intergovernmental Panel on Climate Change (IPCC) from 2013 onwards.

These concluded that humans have been the “dominant cause” of global warming since the 1950s. However, Allgaier found that the message of 120 of the top 200 search results went against this view.

To avoid personalised results, Allgaier used the anonymisation tool Tor, which hides a computer’s IP address and means YouTube treats each search as coming from a different user.

The results for the search terms climate, climate change, climate science and global warming mostly reflected the scientific consensus view. Allgaier said this was because many contained excerpts from TV news programmes or documentaries.

The same could not be said for the results of searches related to chemtrails, climate engineering, climate hacking, climate manipulation, climate modification and geoengineering. Very few of these videos explained the scientific rationale behind their ideas, Allgaier said.

Most of these videos also supported the chemtrail conspiracy theory, which claims toxic substances are sprayed on to members of the public from the condensation trails from aircraft to modify the weather, control our brains, for biological or chemical warfare, or other sinister reasons.

Allgaier noted, however, that although chemtrails videos received a lot of views, it does not mean the people watching them believed what they were told.

He said it was important to examine the algorithms that decide which videos to show people, but did not suggest YouTube should remove climate denial material.

“Effectively, this would be censorship, and YouTube says they are against censorship,” Allgaier said. “Perhaps they could change their algorithms to prioritise factual information, especially for health and medicine.”

A YouTube spokesperson said: “YouTube is a platform for free speech where anyone can choose to post videos, as long as they follow our community guidelines.

“Over the last year we’ve worked to better surface credible news sources across our site for people searching for news-related topics, begun reducing recommendations of borderline content and videos that could misinform users in harmful ways, and introduced information panels to help give users more sources where they can fact-check information for themselves.”

Allgaier suggested more scientists should start taking YouTube seriously as a platform for sharing information. “YouTube has an enormous reach as an information channel, and some of the popular science YouTubers are doing an excellent job at communicating complex subjects and reaching new audiences,” he said.

“Scientists could form alliances with science communicators, politicians and those in popular culture in order to reach out to the widest possible audience. They should speak out publicly about their research and be transparent in order to keep established trustful relationships with citizens and society.”

The research was published in the journal Frontiers in Communication.