Many people already distrust the idea of creating an atmosphere (at any scale) to solve climate change, fearing negative side effects, unfair impacts on different parts of the world, or the prospect that a world awaiting such solutions will feel less pressure to address the root causes of climate change.
Adding business interests, profit motives, and wealthy investors to this situation only creates more cause for concern, complicating the ability of responsible scientists and engineers to do the work necessary to advance our understanding.
The only way these startups will be able to make money is if someone pays for their services, so there are legitimate concerns that financial pressure could force companies to lobby governments or other parties to use such tools. The decision, which should be based on an objective analysis of risks and benefits, will instead be heavily influenced by financial interests and political connections.
The need to raise money or generate revenue often forces companies to hype the potential or safety of their tools. Indeed, this is what private companies should do to attract investors, but this is not how you build public trust, especially when the science doesn't support those claims.
It is noteworthy that Stardust talks about his website that he had developed new particles that could be injected into the atmosphere to reflect more sunlight, claiming that they were “chemically inert in the stratosphere and safe for people and ecosystems.” According to the company: “The particles naturally return to the Earth's surface over time and are safely released back into the biosphere.”
But it's foolish for a company to claim that they can create particles that are inert in the stratosphere. Even diamonds, which are extremely inert, can change the chemistry of the stratosphere. First, much of this chemistry depends on highly reactive radicals that react with any solid surface, and second, any particle can become coated with background sulfuric acid in the stratosphere. This can accelerate the loss of the protective ozone layer by spreading existing sulfuric acid over a larger surface area.
(Stardust did not respond to questions about the issues raised in this article.)
In materials presented to potential investors, of which we received a copy, Stardust further claims that its particles “enhance” the performance of sulfuric acid, which is the most studied material for SRM. But the point of using sulfate for such research was not that it is perfect, but that its broader effects on the climate and environment are well understood. This is because sulfate is widespread on Earth, and there is a huge amount of scientific knowledge about the fate and risks of sulfur that enters the stratosphere through volcanic eruptions or other means.
