Mitigation of ultraviolet solar radiation involving calcite

Stratospheric aerosol injection (SAI) is a technique that involves dispersion of ultraviolet (UV) radiation-reflecting aerosols into the stratosphere to block solar radiation and promote global cooling. This investigation explores the use of calcite powder for SAI by measuring its ability to deflect ultraviolet radiation from the sun. Calcite is a common and radiation-resistant form of calcium carbonate (CaCO₃) that is safe for humans and wildlife compared to alternative aerosols. The experiment took place on a high-altitude balloon (HAB) payload. We evaluated the UV blockage of three sets of laminated calcite sheets with varying concentrations based on the readings from two UV sensors. We hypothesized that the sheet with the highest calcite distribution would block the most UV radiation. The results indicated that both sheets with calcite were effective in blocking UV radiation. These findings pose further investigations of the concentration of calcite needed for SAI and sets the foundation for future investigations in the field of SAI using calcite and other substances that are lower risk for humans and wildlife.