As greenhouse gases mount, interest in unorthodox proposals to limit
warming temperatures has grown. Solar geoengineering is one idea:
interventions in the atmosphere that would cool the Earth by reflecting away
a small percentage of incoming sunlight. Inspired by global cooling observed
after volcanic eruptions, it seems solar geoengineering could be technically
quick and simple to implement, but rather imperfect as climate policy.

Public consideration of the technology, however, is blighted by a surreal problem: the online popularity of baseless “chemtrail” conspiracy theories. Chemtrailers claim covert solar geoengineering programs are already underway and polluting the environment with toxic pollutants, as evidenced by aircraft contrails in the sky. The theory is completely false. But belief is surprisingly widespread, enabled by content dissemination practices of social media companies and strong legal protections for online speech.

This Article assesses legal obstacles to regulating chemtrail
misinformation and proposes responses that work within prevailing norms and laws governing online speech. It explains how chemtrail content complicates public deliberation on solar geoengineering and, by extension, hurts the legitimacy of research activities. It also sharpens the general contributions of misinformation scholarship by applying them specifically to chemtrail content. It concludes with recommendations on how to limit chemtrail misinformation’s spread and impact. Reckoning with climate change, geoengineering, and online misinformation is a multigenerational project. Legal and policy analysis must accordingly adopt a long-time horizon when devising regulatory responses.

The legitimacy of solar geoengineering research depends, in part, upon a free and productive public debate of the proposal’s merits and results. Chemtrail content, however, blights public discourse by obscuring facts and amplifying mistrust of scientific experts. Some may be tempted to write this problem off as unimportant. But experience has shown that baseless conspiracy theories can take root, spread, and alter political landscapes when they give voice to widespread anxieties. Chemtrailer narratives speak concretely to solar geoengineering’s most worrisome aspect, namely, the planet’s climate controlled by an unaccountable elite. There is good reason,
then, to believe the idea could spread as scientific research of solar
geoengineering advances, with the consequence of distorting its politics.
Considerations of solar geoengineering governance thus must be
expanded to consider the mass-information structures that shape public deliberation. Misinformation governance in turn must sharpen its focus and analyze separately the different types of popular false information for their social function, appeal, and impact. The foregoing analysis suggests a few immediate measures to take, like more open cooperation between social media companies and outside researchers, or algorithmic design choices that limit
amplification of chemtrail content. But the governance of both solar geoengineering and misinformation are multi-generational projects. It is critical to approach both problems with an eye on the centuries to come.

Information literacy programs and more open governance processes could go far in combating the factors that spur belief in conspiracy theory misinformation. But there will be no going back to the pre-online world, just as there will be no return from the Anthropocene.