Why the for-profit race into solar geoengineering is bad for science and public trust

Many people already distrust the idea of ​​engineering the atmosphere – whatever its scope – to address climate change, for fear of negative side effects, unfair impacts on different parts of the world, or the possibility that a world that expects such solutions will feel less pressure to address the root causes of climate change.

Adding commercial interests, profit motives, and wealthy investors to this situation only creates more cause for concern, complicating the ability of responsible scientists and engineers to carry out the work needed to advance our understanding.

The only way these startups will make money is if someone pays for their services, so there is a reasonable fear that financial pressures could lead companies to pressure governments or other parties to use such tools. The decision, which should be based on an objective analysis of risks and benefits, will be strongly influenced by financial interests and political relationships.

The need to raise money or generate revenue often leads companies to overestimate the potential or safety of their tools. In fact, this is what private companies need to do to attract investors, but this is not how you build public trust – especially when science doesn’t back up these claims.

It is worth noting that Stardust says on its website that it has developed new molecules that can be injected into the atmosphere to reflect more sunlight, stressing that they are “chemically inert in the stratosphere, and safe for humans and ecosystems.” According to the company, “particles naturally return to the Earth’s surface over time and are safely recycled back into the biosphere.”

But it doesn’t make sense for the company to claim that it can create inert particles in the stratosphere. Even diamonds, which are not extraordinarily reactive, would change the chemistry of the stratosphere. First, much of this chemistry relies on highly reactive radicals that react with any solid surface, and second, any particle may become coated in the sulfuric acid found in the stratosphere. This can accelerate the loss of the protective ozone layer by spreading the existing sulfuric acid over a larger surface area.

(Stardust did not provide a response to an inquiry about the concerns raised in this article.)

In materials to potential investors, a copy of which we obtained, Stardust also claims that its molecules “improve” on sulfuric acid, the most widely studied substance in the SRM field. But the point of using sulfates in such studies has never been that they are perfect, but rather that their broader climate and environmental impacts are well understood. This is because sulfates are widespread on Earth, and there is a tremendous amount of scientific knowledge about the fate and dangers of sulfur that reaches the stratosphere through volcanic eruptions or other means.