Scientists from Washington University in St. Louis have refuted the promising idea of using diamond dust to combat global warming. Previous climate models suggested that microscopic diamond particles, if sprayed into the stratosphere, could reflect sunlight and cool the planet while avoiding sulfur’s side effects of acid rain and ozone depletion. However, a new study has shown that even tiny traces of carbon in synthetic diamonds turn them from reflectors into heat absorbers.
The idea of stratospheric aerosol injection (SAI) replicates the natural mechanism of volcanoes. After powerful eruptions, sulfur dioxide enters the upper atmosphere, creating a “mirror screen” and temporarily cooling the Earth, but sulfur aerosols cause environmental damage, so scientists have been looking for safer alternatives. Diamond dust was considered one of the most promising.
Researchers from the McKelvey School of Engineering, led by Professor Rajan Chakrabarti and Associate Professor Rohan Mishra, used first-principles calculations to model the behavior of nanoparticles at the atomic level. It turned out that even with the most economical production method – detonation synthesis – carbon impurities inevitably remain in diamond dust (from 1 to 5% of the mass). These impurities form a hard shell around the diamond core, which does not reflect, but absorbs solar energy.
Previous calculations showed that to cool the planet 1.6 degrees Celsius would require 5 million tons of diamond aerosol to be sprayed annually by aircraft. It is now clear that even such gigantic efforts will not give the desired effect.
The study highlights the importance of detailed contaminant analysis in any geoengineering project. Even subtle chemical pollutants can dramatically change the properties of particles, trigger unexpected reactions in the atmosphere and create new risks. According to scientists, abandoning diamond dust is a necessary step to focus resources on truly promising materials.
Source: phys.org
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