StarTalk Radio Changing the World (Literally)
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Apr 18, 2025 
Daniele Visioni, an assistant professor at Cornell specializing in climate intervention, and Holly Jean Buck, a sustainability expert from Harvard, join the discussion. They explore the concept of geoengineering, debating the feasibility of creating an atmospheric sun shield to combat global warming. The conversation dives into the science behind stratospheric aerosols, their environmental impacts, and ethical considerations. Visioni and Buck emphasize the need for global governance and collaboration in addressing climate change challenges while navigating the complex interplay of technology and society.
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How Stratospheric Aerosols Cool Earth
- Stratospheric aerosol injection mimics volcanic sulfate aerosols that cool the Earth by reflecting sunlight.
- Aerosols last longer in the stratosphere due to low turbulence and dryness, making them more effective for cooling.
Pinatubo's Impact on Science
- The 1991 Pinatubo volcanic eruption released massive aerosols that cooled the atmosphere temporarily.
- Astronomical observations had to be recalibrated due to atmospheric changes after the eruption.
Aerosols Reflect Light Differently
- Aerosols reflect sunlight physically via Mie scattering at sizes matching visible light wavelengths.
- This reflection differs from greenhouse gas warming, which traps infrared radiation emitted from Earth.