Recently, solar geoengineering became a viral topic online after sensational claims linked Bill Gates to the heavy rains around the world. While these claims could be false, they have sparked public interest in a real experimental field of climate science that Gates and other philanthropists have supported for years now.
Unlike vaccines or sanitation projects, Gates has invested personal funds into research exploring whether humans can deliberately “cool” the Earth. One of the main approaches falls under Stratospheric Aerosol Injection (SAI), which is a type of solar geoengineering designed to reflect a small portion of sunlight back into space, slightly dimming the sun to reduce global temperatures. Slightly dramatic in concept, the method remains largely experimental and controversial.
Now the main character for solar geoengineering is calcium carbonate. Unlike conventional sulfate aerosols, calcium carbonate is designed to reflect sunlight while minimizing damage to the ozone layer. Acting as an atmospheric “antacid,” it neutralizes halogen acids that destroy ozone and absorbs less terrestrial radiation than sulfur, meaning that it could cause less heating in the lower stratosphere.
However, uncertainties remain. Scientists do not yet know how calcium carbonate particles will age and behave in the atmosphere. The Stratospheric Controlled Perturbation Experiment (SCoPEx) by Harvard University aimed to study these effects via small-scale releases, but it was ultimately canceled after public criticism.
Understanding the Risks
The critical question in solar geoengineering is not simply “Can it cool the planet?” but rather “What would the broader impacts be on the Earth system?” Could it damage the ozone layer, alter stratospheric temperatures, or change precipitation patterns?
A common analogy compares solar geoengineering to taking painkillers for symptoms. While painkillers reduce discomfort, they do not address the underlying problem. Similarly, reflecting sunlight could mask the “pain” caused by climate change without reducing greenhouse gas emissions. This also creates a moral hazard that the temporary relief might reduce political and social pressure to cut carbon emissions, delaying meaningful solutions.
Moreover, introducing foreign substances into the atmosphere carries inevitable side effects. Most reflective aerosols degrade quickly, requiring constant deployment. If such spraying were to suddenly stop, then global temperatures could spike rapidly which is a phenomenon known as “termination shock”, that poses extreme risks to ecosystems and human life.
Funding and Experiments
Over the past decade, Gates has funded projects like Harvard’s SCoPEx experiment, while other billionaires like Jeff Bezos and Dustin Moskovitz have supported modeling studies and small-scale experiments. Companies like Make Sunsets have conducted limited U.S.-based trials releasing sulfur dioxide (SO₂) balloons. Yet, none of these efforts have any connection to the recent rainfall or other localized weather events.
While viral claims linking Gates to “artificial rain” are false, they have drawn attention to an emerging and controversial field of climate science. Solar geoengineering may one day offer tools to mitigate global warming, but it remains highly experimental, fraught with scientific uncertainties, ethical dilemmas, and potential unintended consequences.
