The New Yorker:

The gloomy arguments in favor of solar geoengineering are compelling; so are the even gloomier counter-arguments.

By Elizabeth Kolbert

Stardust is the name of a small startup with enormous ambitions. The company, which is based in Israel and registered in Delaware, proposes to do nothing less than dim the sun. Its business plan is modelled on volcanoes. In a major eruption, millions of tons of sulfur dioxide get thrown up into the stratosphere. There, the gas reacts to form droplets of sulfuric acid that scatter sunlight back to space. The result is that less energy reaches the Earth and the planet cools. After Mt. Pinatubo, in the Philippines, blew its top, in 1991, average global temperatures dipped by almost one degree Fahrenheit.

Stardust seeks to market eruptions of its own. It is working to develop highly reflective particles that could be sprayed above the clouds, where they would drift around, mirrorlike, and, the theory goes, help combat global warming. The company calls this scheme “sunlight reflection technology,” although it is more commonly known as solar geoengineering. In one form or another, the idea has been kicking around for decades, but Stardust has taken it a major—some might say terrifying—step forward. The company says that it has created a new sort of reflective particle, the specific makeup of which it has so far declined to reveal. (It states that the particles are made from a material that is “safe for humans and ecosystems.”) And recently it announced that it had raised sixty million dollars in venture capital to pursue its plans, which include developing a dispersal system that could be used to spray the particles into the stratosphere. (Investors include several firms based in the United States, including Future Ventures, headquartered in Los Altos, California, as well as several funds from Europe.) Stardust itself is not planning to deploy any of the technologies it’s creating, a move that would require specialized aircraft. As one of the company’s co-founders, Yanai Yedvab, explained to me in a Zoom interview the other day, “We see ourselves as the technological enablers, which develop the tool kit and provide the information for decision-makers in the different governments that will be involved.”

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