"They would weigh a gram each, be launched in stacks of 800,000, and remain for a projected lifetime of 50 years within a 100,000-km-long cloud. The concept builds on existing technologies. It seems feasible that it could be developed and deployed in ≈25 years at a cost of a few trillion dollars, <0.5% of world gross domestic product (GDP) over that time."

Oh FFS. If we have a few $trillion to devote to global warming, we can enormously reduce it using known technologies.

There is an important clue in this spectacular self-own to the emotional allegiances of the people who get excited about ideas such as this one.