Should the World Ban Solar Geoengineering? 60 Experts Say Yes

They say the technology poses an “unacceptable risk.”

Last weekend, an underwater volcanic eruption covered the island nation of Tonga in ash. It sent tsunami waves surging across the entire West Coast. And it also released a cloud of sulfur dioxide, a chemical that, in large enough quantities, reflects the sun’s rays and cools the planet.

Scientists quickly determined that, unlike Mount Pinatubo’s eruption in 1991 — which cooled the planet by around 1 degree Fahrenheit for several years — the Tonga volcano hadn’t released enough sulfur dioxide to alter global temperatures. But the eruption illustrated a question that has been dogging scientific and climate experts for decades: If the world got unbearably hot, should scientists and governments opt to put sulfur dioxide or similar chemicals into the atmosphere to slow the rate of global warming? Is it ethical to even research such technologies?

In an open letter published Monday in the journal WIREs Climate Change, more than 60 researchers from around the globe offered a resounding “no” to both questions. They called for an “international non-use agreement” on so-called solar geoengineering technologies, which would cool the planet by releasing sun-reflecting chemicals into the atmosphere. The authors want governments to ban outdoor experiments and deployment of solar geoengineering, prohibit national funding agencies from providing financial support, and refuse patents for such technologies. The signatories included many prominent climate scientists, as well as the writer Amitav Ghosh and Sheila Jasanoff, an expert on science policy at Harvard’s Kennedy School of Government.