Researchers at Washington University in St. Louis used first-principles calculations to test whether synthetic diamond dust could work for stratospheric aerosol injection (SAI), a proposed solar geoengineering method. SAI seeks to mimic volcanic eruptions that send sulfur dioxide into the stratosphere and reflect sunlight; because sulfate particles have known harms, scientists have explored other particles that might reflect sunlight with fewer side effects.
The team focused on nanodiamonds produced by detonation synthesis, the most economical method for large-scale production. Detonation synthesis makes diamond soot by exploding a carbon-containing mixture inside a metal chamber. The simulations show detonation-produced dust inevitably contains residual carbon impurities, typically 1–5% by mass, and high-temperature detonation introduces sp2-hybridized carbon that can form a hard carbon shell around a diamond core. These carbonaceous impurities increase absorption rather than reflection and can reduce light scattering by up to 25%.
Earlier research estimated that about 5 million tons of diamond particles would need delivery to the stratosphere each year to cool the planet by 1.6 degrees Celsius, using high-altitude aircraft. Given the new results, the authors conclude detonation-synthesized nanodiamonds would likely absorb more heat than they reflect and are therefore a poor choice for SAI. The paper, published in the Journal of Aerosol Science, lists coauthors and notes support from a 2024 grant by the Simons Foundation International and computational resources via allocation DMR160007 through the ACCESS program, supported by the National Science Foundation.
- Coauthors: Rajan Chakrabarty and Rohan Mishra
- Postdoctoral scholars: Joshin Kumar, Gwan-Yeong Jung, Taveen Kapoor
Difficult words
- stratospheric aerosol injection — deliberate release of particles high in atmosphere to reflect sunlight
- nanodiamond — extremely small diamond particle measured at the nanoscalenanodiamonds
- detonation synthesis — method that creates diamond soot by controlled explosions
- impurity — small unwanted substance mixed into a materialimpurities
- absorption — process where material takes in light or heat
- light scattering — change in light direction after hitting particles
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Discussion questions
- What are the main advantages and disadvantages of using diamond particles instead of sulfate particles for stratospheric aerosol injection, based on the article?
- How might production methods, like detonation synthesis, affect the environmental suitability of a material for large-scale climate interventions?
- What further research or tests would you suggest before considering any particle type for stratospheric aerosol injection, and why?
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