Until recently, the idea of solar radiation modification was a speculative niche of climate science. That has changed fast. Private firms are exploring solar geoengineering as a commercial opportunity: Last year, a US-Israeli startup called Stardust Solutions raised $60 million, and in May it released details of a suite of new inventions it claims would give humans the ability to dial down the global temperature as desired. In August, Elon Musk, whose company SpaceX might be a candidate for delivering geoengineering interventions, threw his voice behind solar geoengineering, writing on X: “Space satellites to control temperature and massive geo-engineering will be needed or it will be game over.”