Stardust Solutions, an Israeli-US startup founded in 2023, has announced a plan to cool the Earth by spraying reflective particles into the atmosphere. The company, led by former Israeli government nuclear physicists, stated its solar geoengineering technology could provide 0.9 degrees Fahrenheit of cooling for an annual cost of $10 billion. The strategy involves using high-altitude aircraft or balloons to disperse particles into the stratosphere that reflect solar energy back into space, mimicking the cooling effect seen after major volcanic eruptions.
The company reported that it has raised $75 million from investors to develop its proprietary particles. Unlike previous research focused on sulfur dioxide, which can cause acid rain and ozone depletion, Stardust Solutions has produced two specific particle types: one made of amorphous silica and another featuring a calcium carbonate core with a silica shell. CEO Yanai Yedvab stated these materials are safe, noting that amorphous silica is already used as a food additive and was used by the Department of Homeland Security in a 2016 New York City subway simulation to model biological attacks.
Scientists and academic experts have expressed concerns regarding the potential unintended consequences of the technology. Raymond Pierrehumbert, a professor at the University of Oxford, warned that a sudden cessation of the program could trigger "termination shock," resulting in catastrophic warming within a few years. Additionally, David Keith, a professor at the University of Chicago, questioned the company's safety claims, citing the "hitchhiker hypothesis" where atmospheric particles might collect harmful metals. Other researchers noted the risk of altering global rainfall patterns and monsoons, which could impact food production.
A person would not see immediate changes in their daily life during the testing phase, but a full-scale deployment could eventually impact local weather, rainfall, and agricultural yields. The company claims the particles fall out of the atmosphere after approximately one year, which Yedvab says allows governments to adjust cooling levels and avoid termination shock. However, atmospheric scientists like Sarah Doherty of the University of Washington argue that current science does not support driving society toward specific geoengineering approaches.
The proposal sets a precedent for private, for-profit entities to manage global climate systems. If successful, it could provide a tool to buy time for reducing fossil fuel reliance; however, critics fear it may reduce the incentive for governments to make pollution cuts. Stardust Solutions intends to begin outdoor testing within the next few years, though specific dates are not yet established. These tests are expected to be conducted under government supervision following the company's engagement with policymakers to create a regulatory framework.